When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I would try to find where the problem is with the existing wiring. It's almost always near the engine as that is where you have vibration and moisture and heat. Also might want to check where the harness enters the cabin under the passenger wheel well liner - below/behind the power antenna. Also check that the wire insulation hasn't shrunk and pulled the pin out of the ECU connector. One of my wires did that also. I had to address a lot of shrunken insulation and bare wires on my car. Most of the connectors can still be purchased as they are weatherpack of one kind or another.
Another thing to note - just because the meter shows 5v, you can't be sure that it can carry a load. You need to also check the voltage with the sensor plugged in (backprobe) so you are loading the circuit. Sometimes the corrosion or poor connection can show 5v on your meter but when you actually plug in the load (CTS) the voltage will drop to nothing.
GD
Last edited by GeneralDisorder; 04-23-2017 at 01:49 PM.
If it turns out to be a ground wire issue inside the ECM can I just ground the wire to chassis ground? Or does it have to ground in the ECM
Here is what I have been doing if I have been doing it wrong please let me know. I'm new at this dvom stuff but I wanna learn it, I set my dvom to 6v under "battery test" I attached my probes to pins 3 and 7 when I turned the key to on with sensor disconnected the dvom jumped all over the place on voltage. So I switched my black probe to a local ground source ( door jamb bolt) and got 4.96v on pin 3. I kept the black probe on the ground bolt and switched the red probe to pin 7, got the same 4.96v I went to the engine bay and tested the connector the same way this time I used the battery as a local ground and got 4.96 for pin 410 and 4.97 for pin 452. When I connect both probes to both pins I get the jumpy voltage and never settles on a voltage, does the same thing when I tried the VDC setting on my dvom. I dipped my sensor in the boiling water and got 200 ohms and when it cooled down I got about 500. I'm not sure how hot the water was but it should have been about operating temp for the car or close to it the steam was burning my hands
I tried to see the resistance with the sensor connected also. That's when I got 206 ohms at sensor and 197 at pins 3 and 7
Last edited by 87tunedport; 04-24-2017 at 08:28 AM.
Well my first inclination is that the ECU's ground pin is shorted to it's 5v sensor rail. But check the ground supplies to the ECU. It may be feedback of some kind because the ECU isn't getting a good ground. In some systems there is a difference between chassis ground and "sensor" ground and it does need to complete the circuit to the ECU so it can sense the resistance.
One of these is extremely useful to sort out real voltage (that can carry current) from false voltage that is only enough to give reading on your meter..... It sucks but a plain DVOM isn't all that useful for low voltage wiring diagnostics since it can't tell you if the circuit can actually carry any current without doing a voltage drop test with a proper load in the circuit. The LoadPro simplifies this test and adds this functionality directly to your existing meter.
is it possible with the emissions gone (smog, EFE, EGR) would i have problems with the coolant temp sensor?
some people say the emissions is not monitored some say it is, my mechanic thinks my problem is with that
Side note, anybody have the part number for the OEM part? I threw mine away thinking I was done with it but I should have kept it to get part number
Well your mechanic should get a manual and find out for SURE.
Does he have some reason for assuming a coolant temp sensor code is related to any of the emissions equipment? The factory service manual does not show anything in the electrical diagrams that would indicate this.
There are no codes related to the smog reactor or the evap system. Therefore they are not monitored. It does have an EGR code but what would that have to do with the coolant temp. In my experience - nothing.
You need a factory service manual, and a mechanic with a scope not one with a theory he pulled from his backside.
If it's missing the EGR - chances are good you will run into that code once you get the CTS working. EGR is disabled during warm up so till the computer knows the coolant temp and enters closed loop it probably will not throw that code. You haven't got it to proper operating conditions yet to encounter that.
no he has no reason for thinking that just a guess.
i know the egr is missing the solenoid and have plans in place to purchase one once the CTS issue is resolved ill know i have to at least start there. if i have to replace the EGR also then so be it i will get the codes cleared one way or another
The EGR will not set a code, so no need to worry about that.
I beg to differ. If the EGR solenoid is not hooked up (or has an open circuit), it will turn on the SES light and set a code.
Also, if the EGR solenoid is hooked up but the vacuum isn't, or if the EGR ports in the manifold are plugged, it will set a code (but may not turn on the SES light). The ECM looks for a manifold vacuum drop when the EGR is commanded open - if it doesn't see it, it'll set a code.
To update everyone the Delphi sensor I ordered also did not work it took longer to throw the code 15 but it did. Makes 3 brand new sensors I tried and did not fix.
How can I check the ECM to see if it's bad? I did have to replace the fuse so something shorted it out. I just got the car back from the shop and they think it's got a short in the ground, but I wanted to rule out ECM
Side note, I started looking into OBD1 scanners with live data and ran across ALDLDroid. Anybody use this? How about install/setup?
Last edited by 87tunedport; 04-26-2017 at 08:33 PM.
What do they mean by a "short in the ground"? That would have to be a short to positive? That would surely be blowing fuses.
Did they mean an "open ground"?!?
Find a shop that knows electrical. These bumble****s clearly don't.
I have ALDLdroid setup on my car/phone. It requires a Bluetooth adaptor.... I don't know if definition files exist to interface with the E4ME computer.
Contact these guys and ask. They were very helpful in getting mine setup. Mine is TPI which is very well documented and supported and it still took some digging to find the proper EPROM definitions.
Honestly I kinda doubt it will work on the carb system for lack of defs but you should ask.
You need to be pretty tech savvy to set it up.
I don't think you have a sensor problem. I think it's got to be wiring or the ECM. My 86 TPI ECM was shot when I got the car. Cracked circuit board. Never could find the crack but process of elimination ruled out all other causes. $86 for a new updated ECM problem solved. But you have to rule out other more common problems.
GD
Last edited by GeneralDisorder; 04-27-2017 at 12:58 AM.
ok i did some more checking with my multimeter (i found a couple youtube videos from expert village)
with the sensor connected and key on i measured the power and got 4.96v with black probe on battery ground
then i switched the black probe to the sensor ground and red probe on battery positive key still on i got 7.30v, then they told me to crank the engine and i got -4.96 (??)
then i disconnected sensor (key off) and put black probe to yellow connector and red probe on battery positive and got 12.70
they said do the same test but disconnected the ECM completely, the voltage just kept increasing and never stopped.
does any of this help or am i listening to more idiots try to diagnose?
also i finally found a shop manual and also ordered a Innova 3140E scan tool. its advertised to do live scanning and work with OBD1 and 2 and has several different adapter plugs. both are on the way
That first video is very confusing the way it is voiced with a computer. You can't tell if "it" is saying ECM or ECT in part of it..... useless.
That's an expensive scanner.... I dont think it's going to help though since it doesn't appear to be able to do live data based on what I'm reading in the manual:
Page 95. All it does is pull codes, and clear them. Which you can already do.
There is plenty of cheap or possibly free software for a laptop, etc that can do it if you get a proper cable. WinALDL I believe is one of them
If you are going to spend that kind of coin.... The Edelbrock carb is like $350..... just saying.
You could not be doing this right now - you could be upgrading or fixing something on the car that's really going to make a difference in the experience of driving it. Like rear end gear ratio....
if i do the Edelbrock carb i would also have to do the distributor so thats even more coin. before the guy shipped it out i cantacted him and requested a cancel because i ran across that read as well
even still i cant stand SES lights they annoy the hell out of me and i hate pulling bulbs just as much. after all this frustration with this s**t i would love nothing more then to rip it all out and burn it
that said i no longer believe its the wiring. i did as you suggested i unwrapped the electrical tapped wire looms and examined the wires in the engine bay. none were broken or cut into. so now im shifting more towards the ECM. i found a good used one on ebay for 35 so im gonna try it out. where does it ground at?
You could even find one used. Post a thread here in the wanted section, or check www.car-part.com for yards in your area that may have what you are looking for.
Used is a crap shoot. I got a new-in-box TPI ECU for like $86 from ebay. I try to find NOS stuff when it comes to that. Try not to troubleshoot with Visa though. Why not find a shop that can do electrical diagnosis and preferably is familiar with the CCC system. Especially if you are getting a factory service manual for reference.
So I just had a knock at my door, it was the PO and he handed me this. Said he had no use for it and since he bought it for the car he didn't want it anymore.
So what is your recommendation for carb? I will probably need a geometry corrector for the TV cable also right? And if I do this can I pull all the computer stuff out? Advice please
What do you recommend from here out?
Side note this is my temp at full warn up would that have anything to do with the SES
If you do it, you can pull all the computer stuff. Or you can just pull it's SES bulb out of the cluster and leave it to do nothing with no carb to operate.
Now the manifold and/or adaptor I'm not totally sure on. Firebird hood clearance, etc. You will have to use a drop style air filter. And probably the thinnest adaptor you can find or a cheap ebay intake manifold for a square bore....
Looks like the right adaptor. Ask the seller if it's for a q-jet, etc. Seems like a good deal.
There will be some things to figure out. Mechanical though mostly. I just put one on a 1956 Buick Roadmaster last weekend where modifications were needed to the adaptor, linkage, and wiring. Runs excellent though. Like a new car.
i still have the ECM coming (ordered before i got the distributor) so if the new ECM does not fix my problem ill probably just go with that carb setup and look for an adapter.
still, what about the geometry corrector? i didnt see one in the link you posted
Search craigslist too - if you search "small block intake" there will be tons of stuff that comes up. I just checked there's like a dozen in my area. Very common. Could call some hot rod shops too and see if they have used stuff. Lots of ways to find this stuff cheap - swap meets, etc. You can get this done on a budget for sure.
My concern with using an adapter is hood clearance in the firebird. It may work. I would search the forums or start a thread to ask specific questions regarding the install. I HAVE NOT done this on my firebird. I've used them on a lot of other small block (and now a 322 Buick Nailhead) applications with excellent and troublefree results. The Edelbrock (Carter AFB basically) is super simple, reliable, and easy to tune once you know how. Takes about 10 minutes to swap out metering rods and such. It has some advantages over some of the older Holley's in that it doesn't have removable fuel bowls to leak, and there's some advantages to the power valve arrangement for forced induction.... etc. They just don't really like BIG cams and highly modded engines. Low idle vacuum doesn't work well with their design like it does with a Holley.
GD
Last edited by GeneralDisorder; 04-28-2017 at 10:43 AM.
so i continue to tinker with the car while i wait for the manual and computer and i tested the CTS ground wire right at the ECM pin and got 7.27v so kinda seems weak ground IDK. maybe if i can find what pin the ECM grounds at i can rule out the ECM.
Last edited by 87tunedport; 04-28-2017 at 10:38 AM.
so i continue to tinker with the car while i wait for the manual and computer and i tested the CTS ground wire right at the ECM pin and got 7.27v so kinda seems weak ground IDK. maybe if i can find what pin the ECM grounds at i can rule out the ECM.
Once you get your manual you can find all the grounds that supply the computer and test them. But yes it would seem like that's probably a voltage drop due to a poor ground supply to the ECM. But it could be inside the ECM itself as well.
To really test the ground pin, you need to put a small load on it and see if it can handle . Sometimes test lights are too much load and can damage ECU's so we don't generally recommend that. I use the LoadPro for this purpose. It will load the circuit with 20 milliamps per volt. This is generally safe for the computer. If you want to do this type of testing I highly recommend the tool and book combo:
looks like this thread is gonna go dark for a while then, my manual has not even been shipped yet :/ ill probably wind up giving the car a nice wash, putting her up in the storage unit until the parts/book arrive.
unless someone can chime in, i cannot find anything pinout related to my ECM 1227169 FFA prom
only the 165 tuned port ECMs
Testing all this would be a snap with the LoadPro and a decent DVOM such as I linked above. If your serious about troubleshooting 30 year old, primitive computer systems such as this, you ARE going to have to invest in the tools to do it adequately, accurately, and quickly.
GD
Last edited by GeneralDisorder; 04-29-2017 at 03:47 PM.
ok i tested pins "A" and "U" for ground and got 12.23 for "U" and 12.06 for "A" then i started the engine and ohm tested pins "3" and "7" and with engine running i got .332 engine was not at full temp but almost there
i dont have an incandescent test light can i use the continuity setting on my DVOM to check that?
with the sensor connected i hooked my DVOM to pin 7 (black probe) and battery positive (red probe) key off i got 12.78 i turned key to on and then ground dropped to 7.06
Last edited by 87tunedport; 04-29-2017 at 06:10 PM.
The test light simulates a load on the ground. The DVOM will only tell you there *is* a connection, it will not tell you if it's any good or not for passing current. Think about voltage as pressure and current as flow. You can have pressure, but not have the ability to get any flow. Like the air in a tire - at 35 psi you have pressure but no flow at all unless you poke a hole in it. The size of the hole determines the flow and the flow is what actually does "work" - you need the ability to have both - pressure (voltage) and flow (current). When you test with a DVOM you are only testing pressure and that there *is* a connection. It tells you nothing about if that connection can do work for you by passing a reasonable amount of current. In an of itself the DVOM is not very useful unless you know how to perform a voltage drop test with it. The test light basically does this because it is a resistive load and takes real current to illuminate the lamp.
i went ahead and ordered that LOADpro figiured it will be of use with my other 2 vehicles as well. can i use it right at the connector for the CTS? its gonna back feed isnt it?
Yes you can use it at the CTS connector itself. You can use the negative lead on the CTS ground and the positive at battery positive to check if the ground can carry a load or not. You can reverse the leads to check if the 5v supply side can carry a load to battery negative as well. Read the book that comes with it. It will help you with more than just this scenario.
side note my manual still has not shipped so thanks again for that pin out page
the computer i ordered is gonna be delivered Monday but ill wait to see what this LOADpro does
check engine is off. i drove the car up to 55 all over have not seen any CEL but now trans is acting weird in OD im gonna swap the PROMS and see what happens
i went to the local salvage hunting for a console lid but ran across this EGR solenoid so i picked it up, grabbed a TVS too got both for 10
i have the electrical connector in the engine bay but none of the vacuum ports are labeled so which one goes to the EGR and which goes to the vacuum source?
If it's a two port valve then it doesn't matter which one goes to which line. If it's a three port valve then you can put 12v to it and figure out which ports open. You want it hooked up such that when the valve is energized the EGR is hooked to the vacuum source and when it's not energized the EGR is vented to atmosphere though the third port and the vacuum port is closed off.
to update everyone on this project. its been about 2 weeks and i have not seen the SES light. car is functioning great. getting good mileage, and performs well. i have moved onto other things on the car such as brakes and maintenance.
also i have driven the car for like a week before i got the EGR hooked back up with the solenoid and did not see SES before that either. i think gearhead was right, or somebody modded my new ECM to not see EGR IDK
also i have driven the car for like a week before i got the EGR hooked back up with the solenoid and did not see SES before that either. i think gearhead was right, or somebody modded my new ECM to not see EGR IDK
The SES light comes on for the EGR code if the solenoid is not hooked up electrically. If the solenoid is hooked up electrically but not the vacuum, it sets a trouble code but doesn't turn on the SES light.
Could someone tell me what this is its in the engine bay right behind the driver sived head light my reason for asking is the line on the right side leads to two other lines and they aren't connected and i dont know where they go
04-23-2017, 01:45 PM
