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Old 04-17-2017, 01:10 PM   #51
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Re: oxygen sensor

so i do have the air cleaner on and connected right then, any idea on why the engine idles at 400 until i unplug the vacuum line on that tee?
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Old 04-17-2017, 01:33 PM   #52
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Re: oxygen sensor

The PO may have adjusted the idle to compensate for a vacuum leak they experienced. You are now correcting the issue and the engine is idling normally. If you need to adjust idle speed, there is a screw on the driver side for that purpose. Normal idle sped in gear and at operating temp is 600rpm. With the car idling in Park, it will be around 800rpm. That screw on my carb is a Torx head and not easy to get to. Some folks just use a needle-nose plier.

In post #46, you can see the screw I mentioned in your third photo. Under the "Quadrajet" logo on the side. It will only take perhaps 1/2 to a full turn to bring it in.

Last edited by gearhead141; 04-17-2017 at 01:37 PM.
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Old 04-17-2017, 02:43 PM   #53
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Re: oxygen sensor

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Originally Posted by gearhead141 View Post
The PO may have adjusted the idle to compensate for a vacuum leak they experienced. You are now correcting the issue and the engine is idling normally. If you need to adjust idle speed, there is a screw on the driver side for that purpose. Normal idle sped in gear and at operating temp is 600rpm. With the car idling in Park, it will be around 800rpm. That screw on my carb is a Torx head and not easy to get to. Some folks just use a needle-nose plier.

In post #46, you can see the screw I mentioned in your third photo. Under the "Quadrajet" logo on the side. It will only take perhaps 1/2 to a full turn to bring it in.
thank you for the info ill give that a shot and report back

hopefully the MCS will be delivered soon, if not maybe ill take the one out of the old carb and put it on the new one
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Old 04-17-2017, 03:31 PM   #54
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Re: oxygen sensor

Got the idle up to 7-800 idles good now here's some pics of new air cleaner installed and new CTS

It's getting there
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Old 04-18-2017, 08:30 AM   #55
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Re: oxygen sensor

since i have never done a MCS before or really worked on a carburetor (my last carb vehicle was a 77 Mustang II 7 yrs ago) i decided to attempt removing the MCS from the old carb just as practice while i wait for the part to be delivered. i got the air horn off, i pulled out primary rods, plunger, spring, TPS, and accelerator pump (took secondary rods out before i took off air horn) the gasket did not make it, but i expected that with being over 30 yrs old. im looking at the MCS in the fuel bowl but i cant seem to get it out. i looked at this thread
https://www.thirdgen.org/forums/carb...-ccc-qjet.html (re-building a ccc-qjet carburetor)
it says its held in place by the lean stop screw. where is that screw i know he is not talking about the silver one that held the connector in place.
i got the black retainer out with my finger nails so i have a direct look at the MCS and float. not seeing any more screws i also took throttle plates off and looked fron underneath and alot of carbon but no screw. i know its probably right in front of me and hopefully you guys are gentle and wont pick on me for asking but i dont wanna force anything in this carburetor either in case i need it i would rather ask. could the carbon buildup be strong enough to be keeping it in place?

i got it figured out. its the long stem attached to the MCS. i didnt count the turns but i will when i take the other one apart but now i have the MCS out the float and the needle

now im gonna try to put it back together, good practice
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Old 04-18-2017, 01:27 PM   #56
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Re: oxygen sensor

would it be a good idea to invest in a dwell meter?
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Old 04-18-2017, 03:14 PM   #57
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Re: oxygen sensor

Well, unless you have live scanning capability, that's the way the MCS dwell is set, so...

(Don't forget, 6 cyl setting on the meter.)
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Old 04-19-2017, 07:42 AM   #58
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Re: oxygen sensor

Well I got good new and bad news. Good news is the MCS arrived yesterday and I got the carburetor pulled. Bad news is the damn PO hard wired the electronic choke to this wire harness on the wiper motor.

This probably explains why my wipers don't work. Is that just a 12 v source for the choke? Or is there another reason it's wired in? What do you guys recommend? I'm thinking I should just wire up the rest of the wire so I have my wipers back but IDK

I had to cut the wire for choke because the is no connector to unplug and it's soldered to the choke
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Old 04-19-2017, 09:02 AM   #59
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Re: oxygen sensor

well...the install went pretty smooth thanks to the threads on this site. i took my time and did things carefully (counted 13 turns out and back in, 90% sure lean stop screw is in same spot). i have the carburetor all ready to go back in the car. hope i dont blow myself up lol

the carburetor was full of gas so right now my kitchen reaks i have my windows open and my fan on high hope it wont last the house was just rebuilt
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Old 04-19-2017, 09:07 AM   #60
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Re: oxygen sensor

here is a pic ready to go back in the car
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Old 04-19-2017, 10:14 AM   #61
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Re: oxygen sensor

The choke may have been damaged when that wire was soldered on. You can pick up the proper connector at your local parts house. The proper wire for the choke should be light blue, or so it says for an '85 model. So, look around in the wire harness on the passenger side of the intake manifold for that wire. And yes, it is a constant hot but it comes from a dedicated relay.
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Old 04-19-2017, 11:31 AM   #62
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Re: oxygen sensor

well first i got the carburetor back on unfortunately i have to wait to start up because i forgot to put a rag over the fuel line (i just propped it upward through the heater hoses) gas filled up the line while i had the carburetor off and started spilling out. the intake manifold, the exhaust manifold, the floor have gas all over so ill have to wait for it to evaporate (its how i learn right?)

i did find the light blue wire on the passenger side wire harness seen in the pic.

where is the relay for the choke located? i may want to either replace it or take a look at it. the PO told me the choke was not working which is why he replaced the carburetor but the problem could be in the relay
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Old 04-19-2017, 11:40 AM   #63
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Re: oxygen sensor

The relay is located in the "Convenience Center", which if you know anything about these cars is far from convenient. It is under the instrument panel to the right of the steering column. Rather than go through all the frustration of checking that, just see if there is 12 volts at the light blue wire when the key is turned on.
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Old 04-19-2017, 11:54 AM   #64
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Re: oxygen sensor

thanks ill check right now
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Old 04-19-2017, 12:56 PM   #65
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Re: oxygen sensor

while i was working on the carb i noticed a electrical connector i believe its for the EGR solenoid. im looking for a replacement but since i dont have the original one i found this on ebay will it work for my car?
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Old 04-19-2017, 02:39 PM   #66
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Re: oxygen sensor

Quote:
Originally Posted by gearhead141 View Post
The relay is located in the "Convenience Center", which if you know anything about these cars is far from convenient. It is under the instrument panel to the right of the steering column. Rather than go through all the frustration of checking that, just see if there is 12 volts at the light blue wire when the key is turned on.
ok i checked and i have 11.2v at that light blue wire for the choke so im assuming everything is working at the choke and i should just wire in a connector and remove that crap the PO wired in

the MCS and CTS was a success and turned off the SES light. but will it go back on when i driver her and the EGR engages, without that solenoid will it trigger again?
is it normal for the MCS to click constant? almost sounds like a jackhammer

i have to make some adjustments to the carb again cause the engine was running at 1000 at full operating temp. the fuse for the ECM was blown so up until then the engine was running like s***

Last edited by 87tunedport; 04-20-2017 at 02:16 AM.
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Old 04-20-2017, 01:54 AM   #67
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Re: oxygen sensor

The EGR will not set a code, so no need to worry about that. Yes, the MCS will click for about a minute or so, maybe less.

That EGR solenoid in your photo looks correct. It is connected to ported vacuum on one side and to the EGR valve on the other. It is mounted on the passenger side of the intake manifold on a bracket.

Here is a photo of where and what it looks like.
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Last edited by gearhead141; 04-20-2017 at 01:58 AM. Reason: add phot0
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Old 04-20-2017, 02:12 AM   #68
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Re: oxygen sensor

Thanks I found that exact connector on the passenger side intake so I'll see if I can grab a solenoid off eBay and restore EGR function

I actually wonder how long the car was in limp mode with the blown ECM fuse. Now the car seems to have gained some power and runs so good now. I'm gonna have to make some adjustments to the idle but sounds so much better then she ever did since I got her
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Old 04-20-2017, 08:58 AM   #69
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Re: oxygen sensor

i went made some adjustments today i also hooked up the light blue wire back to the choke, removed that wire going to my wiper motor, reconnected the wiper motor wires. i have my wipers back but i do not believe the choke is working. it took alot to get her running and even running cold she was idling at normal operating temp idle

how do i diagnose the choke? i already checked the light blue wire has 11.2 v with key on

the code also returned for the CTS i dont know why its all connected still. i disconnected the battery and it went away again so im not sure whats up with that
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Old 04-20-2017, 09:50 AM   #70
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Re: oxygen sensor

so i was looking at this thread
https://www.thirdgen.org/forums/tech...operation.html (Electric Choke operation)

maybe i have a problem with my fast idle cam? who knows what the PO did to this carburetor, and now i fixed the issues maybe i need to do more adjustments?

also i should mention when i connected the light blue wire to choke i used a usual parts store wire connector crimped onto the wire. is the actual pigtail important to function the choke?

lastly it says in that thread the choke need full 12v, since i got 11.2 would that make a difference or not?

as usual any help gets me closer to getting this car running right and i could not have gotten this far without you guys helping me
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Old 04-20-2017, 11:27 AM   #71
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Re: oxygen sensor

That thread explains it very well. Have you done the resistance check on the choke coil? When you said it had been soldered, I thought that probably killed it. Just as it said in the post, as soon as you step on the gas, the choke plate should snap shut. If that isn't happening, something is wrong.

The connector to the choke can be purchased at O'Reilly or Autozone, or any number of other parts places. If you can wait, you can most likely get a great price through Rock Auto. In any case, it should be less than $10.

Don't get frustrated, you're getting all the niggling little problems fixed.
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Old 04-20-2017, 02:16 PM   #72
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Re: oxygen sensor

Quote:
Originally Posted by gearhead141 View Post
That thread explains it very well. Have you done the resistance check on the choke coil? When you said it had been soldered, I thought that probably killed it. Just as it said in the post, as soon as you step on the gas, the choke plate should snap shut. If that isn't happening, something is wrong.

The connector to the choke can be purchased at O'Reilly or Autozone, or any number of other parts places. If you can wait, you can most likely get a great price through Rock Auto. In any case, it should be less than $10.

Don't get frustrated, you're getting all the niggling little problems fixed.
Once I get back over I will check the resistance. I was wrong when I tried to disconnect the wire I noticed it was not soldered like I thought, but actually riveted on

Tomorrow I'm gonna head up to O'Reilly and pick up the connector pigtail just to make it right

I know when I looked at the choke plate it opens as warming up but it doesn't get a chance to snap shut cause the plate closes back up as it cools down
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Old 04-20-2017, 03:19 PM   #73
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Re: oxygen sensor

Checked and rechecked I got 7.3v at choke it's 53* outside. I included some pics showing choke plate closed.

Also got pics showing the connector I used on choke


Edit: just checked the choke resistance on old carburetor got 25.6, thought I could swap it out but it's toast

Edit 2: just ordered the L shape connector. comes with a new thermostat also got it for 26.00
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oxygen sensor-tmp_13877-img_20170420_155351-394194629.jpg   oxygen sensor-tmp_13877-img_20170420_1554011843685775.jpg  

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Old 04-21-2017, 07:54 AM   #74
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Re: oxygen sensor

i got the fast idle solved. the fast idle cam needed to be tightened up to engage the step cam. choke plate stays open when hot and i depress gas pedal, it snaps shut idles at about 1300-1500. idle does kick down sooner then i thought and still reaks of gas so i believe she is still running rich.

i turned the idle mixture screws all the way in the 2 turns out had no effect.

also when i turned them all the way in the engine still ran normal no slowing down or speeding up??

then to top it off the code 15 came back again!!!! not until engine has been running for a while will that damn code come on

ill have to run up and grab a vacuum gauge to set idle mixture screws. but as a base setting what do you guys recommend? something like all the way in then 2-3.5 turns out?
ill see if i can get some resistance readings from the CTS. the code 15 comes back when engine has warmed up so must be something the computer does not like

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Old 04-21-2017, 10:38 AM   #75
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Re: oxygen sensor

I know you are having soooo much fun messing around with CCC carb stuff, but have you considered just getting an Edelbrock or Holley for it? They are pretty cheap now. I got a new Edelbrock recently (going on a 56 Buick) for like $350.

I know there seems to be a lot of folks on here that enjoy this computer carb foolishness but the 2017 reality is that this stuff is way outdated and the support for it is poor, etc. If this were anything but a GM product then you wouldn't even be able to get the parts to make it work. I work on a lot of older carb stuff - Jeep, Subaru, Suzuki, Toyota, etc. They all had feedback computer carbs back in the day - which you now can't even buy the parts to make them work. All the stuff is discontinued. So our standard practice is to just swap out to a plain non-CCC carb. In EVERY case people like them better. And there's no frustrating (and pointless) learning curve.

There was a point when I thought the same way - not wanting to be defeated by this 1980's collection of handheld calculator and pinball machine parts. But seriously do you want to be stuck in the 80's? It's fun for a minute but don't you want to DRIVE the car?

My 86 TA is tuned port. And it took me 6 months to get it driving after sitting for 11 years. I basically had to rebuild the fuel system and then in the end - the computer was bad. Cracked circuit board. If I had to do it again I would have just taken the entire manifold off, sold it on ebay, and dropped in a FiTech on a single-plane. All that work and then TPI won't support the power I want for my end-game anyway. I guess I'll use it on my truck perhaps. Good torque for that application.

GD

Last edited by GeneralDisorder; 04-21-2017 at 10:45 AM.
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Old 04-21-2017, 11:13 AM   #76
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Re: oxygen sensor

Quote:
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I know you are having soooo much fun messing around with CCC carb stuff, but have you considered just getting an Edelbrock or Holley for it? They are pretty cheap now. I got a new Edelbrock recently (going on a 56 Buick) for like $350.

I know there seems to be a lot of folks on here that enjoy this computer carb foolishness but the 2017 reality is that this stuff is way outdated and the support for it is poor, etc. If this were anything but a GM product then you wouldn't even be able to get the parts to make it work. I work on a lot of older carb stuff - Jeep, Subaru, Suzuki, Toyota, etc. They all had feedback computer carbs back in the day - which you now can't even buy the parts to make them work. All the stuff is discontinued. So our standard practice is to just swap out to a plain non-CCC carb. In EVERY case people like them better. And there's no frustrating (and pointless) learning curve.

There was a point when I thought the same way - not wanting to be defeated by this 1980's collection of handheld calculator and pinball machine parts. But seriously do you want to be stuck in the 80's? It's fun for a minute but don't you want to DRIVE the car?

My 86 TA is tuned port. And it took me 6 months to get it driving after sitting for 11 years. I basically had to rebuild the fuel system and then in the end - the computer was bad. Cracked circuit board. If I had to do it again I would have just taken the entire manifold off, sold it on ebay, and dropped in a FiTech on a single-plane. All that work and then TPI won't support the power I want for my end-game anyway. I guess I'll use it on my truck perhaps. Good torque for that application.

GD
im interested in retaining the originality of the car. you can look at a couple other threads i started and see how the car looked when i got her vs now. ditching the aftermarket wheels and the air cleaner cost me over 800 bucks

besides i would have to deal with the SES light which really annoys me to a point i will somehow find the emissions stuff and reinstall it to get that damn light off but lets not hope it comes to that

plus the car will run great IMO i just want everything to be right and i already got most of it figured out now im just tuning it all in

Last edited by 87tunedport; 04-21-2017 at 11:17 AM.
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Old 04-21-2017, 01:11 PM   #77
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Re: oxygen sensor

Quote:
Originally Posted by 87tunedport View Post
then to top it off the code 15 came back again!!!! not until engine has been running for a while will that damn code come on

ill see if i can get some resistance readings from the CTS. the code 15 comes back when engine has warmed up so must be something the computer does not like
Your rich fuel condition is likely directly related to the CTS. If the computer doesn't think the coolant is up to temp, it will keep the engine in a rich condition. Even though you have changed out the sensor, there is still a problem with the circuit. Check resistance once again on the sensor to make sure it is working; should be less than a 1000 ohms (depends on coolant temp). If that is good, check the connector. With the key on and engine off, there should be approximately 5 volts across the black wire and the yellow wire. If no voltage is seen then check resistance for an open. If you read negative volts, you've hooked up the new pigtail backwards. For some reason, the ECM is not getting a proper signal for the coolant temp, and after a certain amount of time it will set the SES light.

For the poster who would like you to scrap the whole carb, I hope he realizes that there is a bit more to it than that. The distributor would also have to be replaced, as it is computer controlled. I have given some thought to this as well, but it would cost me upwards of $2500 to install a modern EFI system. I may do that at some point in the future but for now, I can work with what I have.
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Old 04-21-2017, 01:17 PM   #78
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Re: oxygen sensor

once again gearhead thank you for your input , im gonna bring the car home today and work on her tomorrow. i will get the voltage reading and post them today
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Old 04-21-2017, 03:31 PM   #79
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Re: oxygen sensor

ok when i brought the car home the SES popped on again. but i stopped off to get gas when i started her back up to go home the light went off. IDK whats going on here

when i got home i checked the resistance on the sensor and got 23 ohms at full operating temp. so i checked the connector for 12v and got erratic levels and never settled on a voltage.
when i installed the CTS i used the tap in connectors that came with the pigtail. i removed those and just directly connected the wires, shrink tubing, and zip tied the wires to the alternator bracket to keep them away from the heater hoses.

so as of now the SES is random i guess
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Old 04-21-2017, 03:31 PM   #80
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Re: oxygen sensor

Originality rarely includes the POS emissions equipment unless it's a museum car that no one will EVER drive. Since that's not the case, preserving the (craptacular) original emissions equipment is not going to put a single dollar of value back into the car. Especially since it's already not original.

Most people looking at vehicles such as yours - solid daily driver quality - are going to appreciate the modern mechanical touches that make the vehicle better to drive and easier to maintain.

The distributor can be swapped easily also. HEI dristributors are cheap. All of this stuff is cheap compared to the cost of car payments and mandated full coverage insurgence. Remember, most people have to budget for all that every month.

I get where you are coming from. I've been there. But from where I am now looking back down the hill at where you are - trust me - put all that "original" junk in a box under the stairs and if you ever sell the car give it to the next guy. I'm sure he will appreciate making him throw it in the landfill.

I understand EFI isn't in the budget. But NEW carbs are cheap. That CCC junk fest is just causing you unnecessary frustration and a to learn about out dated tech that will never give you a return on the educational investment. It was not a bright spot in the evolution of automotive technology and it's best left in the dust bin of history.

GD
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Old 04-21-2017, 03:38 PM   #81
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Re: oxygen sensor

im not preserving originality of the car for value of resale im doing it because i like keeping my vehicles stock the carburetor on the car is already new. its a stock CCC carb but still new and most of the problems are already resolved thanks to gearhead and threads on this forum


so another test drive no light came on until i pulled into my driveway right as i was about to shut her off, BOOM light came on. i shut her off and restarted light went out idled great and no light. is there some kind of short in the wiring?

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Old 04-21-2017, 03:43 PM   #82
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Re: oxygen sensor

I see. A vehicular masochist. I tip my hat to thee. I guess someone's got to take it for the team. LOL.

Good luck my friend. I hope it works out.

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Old 04-21-2017, 04:40 PM   #83
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Re: oxygen sensor

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I see. A vehicular masochist. I tip my hat to thee. I guess someone's got to take it for the team. LOL.

Good luck my friend. I hope it works out.

GD
i dont appreciate being called a masochist especially when everything is almost there. just because im not gonna throw everything away just to spend an equal amount of time/money (or maybe more) on an upgraded system when the one on the vehicle works just fine.

ya it took some work to get there but i got her there, and would not have spent as much as i would have on your upgrade suggestions.

if it works for some people, great but for me the system in the car works as it is and im almost there to getting her running the way she should. she already runs better then when i got her
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Old 04-21-2017, 06:10 PM   #84
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Re: oxygen sensor

update i got some small paper clips and bent them around the probes of my multimeter the stuck the ends into the prongs of the connector. checked and rechecked i got 59.2 which does not seem right i put the multimeter on the 6v setting
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Old 04-21-2017, 06:31 PM   #85
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Re: oxygen sensor

From what I know of general thermistor resistance vs. temp, the 23 Ohms @ operating temp is likely correct.

Checking the reference (computer) side of the equation requires a dwell meter set on the 6 "cylinder" setting. This is not the same as a volt meter set on 6v.

I'll try to help you with this since you won't listen to reason.

I have a background in electrical, software engineering, and lots of experience with feedback carb systems. Though all this has taught me is to hate them with more intensity. You'll get there.

First off - do you have a dwell meter, do you know what it is, and how to use it?

An oscilloscope would be better if you have one. A Snap-On Vantage Ultra would be better still if you have that

GD

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Old 04-22-2017, 12:06 AM   #86
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Re: oxygen sensor

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From what I know of general thermistor resistance vs. temp, the 23 Ohms @ operating temp is likely correct.

Checking the reference (computer) side of the equation requires a dwell meter set on the 6 "cylinder" setting. This is not the same as a volt meter set on 6v.

I'll try to help you with this since you won't listen to reason.

I have a background in electrical, software engineering, and lots of experience with feedback carb systems. Though all this has taught me is to hate them with more intensity. You'll get there.

First off - do you have a dwell meter, do you know what it is, and how to use it?

An oscilloscope would be better if you have one. A Snap-On Vantage Ultra would be better still if you have that

GD
I hear mixed reviews about the Quadrajet people hate them and love and hate them but when they are tuned properly they provide excellent fuel economy and performance. I'm almost there so I'm not gonna throw it away now

I know what a dwell meter is through research the mixture control solenoid. I do not have one, I was about to order one but I thought I wouldn't need it anymore since I got the solenoid fixed

When I was voltage testing my CTS wiring I didn't confuse the 6v with 6cyl setting on a dwell meter. I was checking for 5v in the wiring

I thought about pulling the ECM and testing the voltage right the for the CTS to see if I can rule out wiring problems. I tested at connector and got erratic results I'll post a video of it tomorrow. The CTS registered 23 ohms at full temp.

The SES comes on but goes off in next key cycle. I could probably go and fire her up now and she won't have any codes
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Old 04-22-2017, 07:16 AM   #87
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Re: oxygen sensor

i think i was doing it wrong i checked voltage at yellow wire grounding the black probe i got 4.97v
checking voltage at black wire with black probe grounded i got 4.96v

i measured the resistance on both wires and got 2.06

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Old 04-22-2017, 07:53 AM   #88
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Re: oxygen sensor

could i have a bad ECM?

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Old 04-22-2017, 12:46 PM   #89
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Re: oxygen sensor

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ok when i brought the car home the SES popped on again. but i stopped off to get gas when i started her back up to go home the light went off. IDK whats going on here

when i got home i checked the resistance on the sensor and got 23 ohms at full operating temp. so i checked the connector for 12v and got erratic levels and never settled on a voltage.
when i installed the CTS i used the tap in connectors that came with the pigtail. i removed those and just directly connected the wires, shrink tubing, and zip tied the wires to the alternator bracket to keep them away from the heater hoses.

so as of now the SES is random i guess
According to my FSM, the resistance reading on the CTS should be in the neighborhood of 185 ohms with the coolant temp at 210 degrees F. If the coolant temp was at 160F, the resistance reading would be 450 ohms. If you are getting a reading of 23 ohms, that is way off. You say you got about 5 volts when measuring across the sensor leads, and that means the circuit is good according to the FSM. I would be suspicious of the sensor or how it is making contact with the coolant.

Just for comparison, on my car, when the engine is up to operating temp, the instrument panel indicator (different sensor) sits just above the mark below the 220. I have to make an assumption that it is about 195 to 200F. That is with a factory thermostat setting of 192. Now, it is not unheard of to have a bad sensor right out of the box, but I would try to eliminate that possibility.

If you want to check the sensor and make sure it is actually working, remove it from the car. Boil a pot of water. With the sensor connected to a multimeter, dip it in the water. If there is a change in resistance and it stabilizes between 150-170 ohms (guesstimate), then the sensor is good. Otherwise, the sensor is bad.

Have you considered looking for a FSM (factory service manual)? It sure has helped me out.
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Old 04-22-2017, 12:54 PM   #90
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Re: oxygen sensor

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According to my FSM, the resistance reading on the CTS should be in the neighborhood of 185 ohms with the coolant temp at 210 degrees F. If the coolant temp was at 160F, the resistance reading would be 450 ohms. If you are getting a reading of 23 ohms, that is way off. You say you got about 5 volts when measuring across the sensor leads, and that means the circuit is good according to the FSM. I would be suspicious of the sensor or how it is making contact with the coolant.

Just for comparison, on my car, when the engine is up to operating temp, the instrument panel indicator (different sensor) sits just above the mark below the 220. I have to make an assumption that it is about 195 to 200F. That is with a factory thermostat setting of 192. Now, it is not unheard of to have a bad sensor right out of the box, but I would try to eliminate that possibility.

If you want to check the sensor and make sure it is actually working, remove it from the car. Boil a pot of water. With the sensor connected to a multimeter, dip it in the water. If there is a change in resistance and it stabilizes between 150-170 ohms (guesstimate), then the sensor is good. Otherwise, the sensor is bad.

Have you considered looking for a FSM (factory service manual)? It sure has helped me out.
i have a Haynes manual i thought that was good enough but i cannot find any engine schematics so ill be on the lookout for that FSM

i pulled the ECM and i was looking it over i dont see any burnt /broken resistors. i have been looking all morning for an engine schematics so i could test the pins but im finding very little for my carburetor car i put everything back together and i will give that sensor test a shot. i would be very happy if thats the problem saves me 90 on a new ECM

yes i had about 5v but with red probe on each wire (not at the same time) and the black probe on a ground (battery) that is the right way right?
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Old 04-22-2017, 01:36 PM   #91
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Re: oxygen sensor

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i have a Haynes manual i thought that was good enough but i cannot find any engine schematics so ill be on the lookout for that FSM

i pulled the ECM and i was looking it over i dont see any burnt /broken resistors. i have been looking all morning for an engine schematics so i could test the pins but im finding very little for my carburetor car i put everything back together and i will give that sensor test a shot. i would be very happy if thats the problem saves me 90 on a new ECM

yes i had about 5v but with red probe on each wire (not at the same time) and the black probe on a ground (battery) that is the right way right?
ok the sensor started at 4.46 at cold. dipping it in the boiling water it went down to .208 should i replace? it did not go as far down as it should have right

i did it again the water was boiling so bad the steam was burning my hand lol. started out at about 500 and it evened out at about 200. im looking at prices for an ACDelco sensor

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Old 04-22-2017, 04:57 PM   #92
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Re: oxygen sensor

well that was money well wasted, i got a BWD temp sensor that came with another pig tail this time i soldered it in and i still got the damn SES light. still goes off next key cycle. but comes back on while driving.

does anybody know the pins on the ECM harness to check? the schematic shown in post 2 confuses me because it shows the black wire turning into a tan wire going into the ECM. when does it turn tan?

im starting to run out of patients with something that should be a simple repair. im about to send to GM to fix

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Old 04-22-2017, 05:35 PM   #93
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Re: oxygen sensor

The CTS sensor circuit terminates at pins 3 and 7 on the ECM connector. Pin 3 is voltage and pin 7 is ground.
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Old 04-22-2017, 10:02 PM   #94
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Re: oxygen sensor






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Old 04-22-2017, 10:05 PM   #95
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Re: oxygen sensor

So you need 5v on the ECM side. Move the wiring around as you test. If it changes look for an intermittent break in the connector or wires near it.

The CTS should be 185 Ohms at 210 degrees F. If it's not then it's not the right sensor or it's bad.

Try looking up the part number and going on eBay for new old stock. That's how I handle things like that. The Chinese replacement parts you get at the parts stores are rarely any good for long if at all.

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Old 04-22-2017, 10:09 PM   #96
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Re: oxygen sensor

As for the Quadrajet - they are GREAT carbs. Have one on my truck. Prefer the Edelbrock when considering aftermarket carbs - its design uses a lot of the Quadrajet concepts.

Rochester spent decades refining that carb. It was beautiful..... Till they added a computer to it.

That's why I say just bolt on an Edelbrock 600. It's a brand new Quadrajet - or as close as you can now get.

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Old 04-23-2017, 07:18 AM   #97
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Re: oxygen sensor

thanks for the help guys, i appreciate it. im gonna get these little gremlin problem fixed if it kills me. i should watch what i type when im angry cause i say things i dont mean (my wife will agree with me) with you guys helping me i will get this sorted out

any way i threw away the old sensor before i could get a part number off it but i did some digging and found this one on Amazon they advertise it as an OE part, think it will work?
https://www.amazon.com/Delphi-TS10075-Engine-Coolant-Temperature/dp/B000CGM9O2/ref=au_as_r?_encoding=UTF8&Make=Pontiac%7C52&Model=Firebird%7C595&Year=1986%7C1986&ie=UTF8&n=15684181&newVehicle=1&s=automotive&vehicleId=1&vehicleType=automotive https://www.amazon.com/Delphi-TS10075-Engine-Coolant-Temperature/dp/B000CGM9O2/ref=au_as_r?_encoding=UTF8&Make=Pontiac%7C52&Model=Firebird%7C595&Year=1986%7C1986&ie=UTF8&n=15684181&newVehicle=1&s=automotive&vehicleId=1&vehicleType=automotive
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Old 04-23-2017, 09:22 AM   #98
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Re: oxygen sensor

so i warmed up the engine and drove her until the SES came on (doesnt take as long with this sensor) i ohm tested and got 197 at ECM and 206 at sensor. i went ahead and ordered that Delphi sensor since it was only 10 but the readings at ECM still dont match what FSM says

could it be in the wiring and the sensor? the difference in ohm reading seems to be in my favor but still triggers SES, is it because its still not going low enough?

edit:i tried to check voltage at sensor connectors i did not get 5v i once again got the erratic readings and cannot get a settled in reading for 5v
i will go get some yellow and black 14 gauge wire and use that other pigtail, wire it into the ECM and see if i get the SES again

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Old 04-23-2017, 10:46 AM   #99
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Re: oxygen sensor

Check the power and ground AT the ECU pins. I posted the troubleshooting chart so you can follow it. It could be the ECU, it could be a ground FOR the ECU. Or it could be the wiring. Don't make more work for yourself and don't troubleshoot with Visa.

Also go on eBay and get a proper factory manual. The one for my firebird pictured above was less than 40 bucks shipped.

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Old 04-23-2017, 12:41 PM   #100
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Re: oxygen sensor

i got 4.96 at power and ground of ECU pins
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