When you turn the key on, there is no check engine light illuminated (bulb test)?
Burned out bulb, maybe?
You can get the codes by jumping pins A & B on the ALDL connector (two upper right).
The connector is by your right knee. If everything is OK, with no trouble codes, you should get a code 12 only.
https://www.thirdgen.org/forums/dfi-...-firebird.html

 

i thought i could still use idle mixture screws to affect idle

You screwed both all the way in and said the engine still ran smooth.
Most likely, it should have stalled.

 

Now I'm wondering if your ECM is in limpback mode, or not working at all?
But you say the MCS "ticks".

Can someone else provide more info, please?

 

No my SES bulb works, i just meant i have no codes KOEO (key on engine off) except for tbe code 12. i was asking if GMs OBD was like Fords and you can do a KOER (key on engine running) to check running systems


I checked my codes and i have none but i never tried with engine running


Correct the MCS makes clicking noises. The engine still ran fine with mixture screws seated. I took them out and cleaned them off but never did the passage inside the carb. I really dont know when it goes but ill shoot some carb cleaner in there. Also just wondering the mixture screws in this carb are flat head screws while i have seen other mixture screws with a double D shape. In fact my idle adjust tool womt even fit these screws. Is it possible the screws are the wrong ones with a shorter length?

 

both flat and double d heads were used. the mech qjet used a coarser thread screw

if no codes show engine off none should show engine on. codes are stored until cleared or the ecm is powered off

1. start your motor and warm it up

2. connect your dwell meter

3. adjust your IAB from 2 to 7 turns out until the dwell begins to respond

if no luck repeat with an incremental change to the idle mixture screws

stop worrying about something being wrong until you have evidence of the fact. nothing so far seems at odds here, but if your O2 sensor is of unknown age or condition, by all means replace it.

 

i would like to replace the o2 just as good measure since i have no history on the car.

does it just use the same o2 as a Tuned Port engine? if not do you have a part number?

 

same part

the one wire O2 sensor is a pretty generic piece.

 

http://www.ebay.com/itm/O2-Oxygen-Se...72.m2749.l2649

just placed an order for this one

side note, i once again removed the carburetor took the throttle plate off, removed the mixture screws, sprayed some carb cleaner inside the holes and bottom of the fuel bowl, the well plugs looked pretty good and do not look like they are leaking. after i let it sit for a little, i blew everything off with compressed air. i reassembled the carburetor with adjustment tools, put back on the car, and once again upon first startup she ran rich but eventually got less rich. i set the TPS to .50 according to the FSM then i turned the mixture screws in one more turn and the car ran even less rich. so i think it helped

im currently in a battle with a seller on ebay over the dwell meter, because i ordered it 3 weeks ago and still have not received it. seller claims he shipped it and keeps telling me "just give it a couple more days" but i had enough, i ordered another one with the o2 sensor and escalated to ebay customer service for a refund.

im not gonna make any more adjustments on the car until i get the dwell meter and check it out hopefully soon. seems online is the only way to get a dwell meter

 

You are going in the right direction.
Stick with your plan - wait for the dwell meter.
You need actual readings at this point - not guessing.

 

thanks for the help so far guys you guys are awesome. Im learning alot about this

Probably not carb related but problem still exists after car sits for 20 minutes theres is hard start. Then idles at 500 and slowly gains rpm to 900. Unless its flooding

 

Well i finall got the dwell meter, now im just waiting for a good day to bring her home. Its been raining here non stop and the roads are flooding

 

On the 80s quadrajet well plugs, I wasn't so sure those were 100% leak proof. But what in the 80s changed from earlier quadrajetts? I put epoxy on mine (JB WELD) and I think they should last a very long time.

To confirm this, I think getting good dwell of 50% with the IAB only 4 turns or less out shows this, right?

 

yesterday i installed the new o2 sensor, that 2500 tool kit had a socket to remove it making life so easy. man i love that tool kit

https://www.youtube.com/watch?v=vX7v...ature=youtu.be

today i got the car home and checked the dwell. at first it was 59.7 and did not move im assuming it was still in open loop, after a while it started registering and i was able to get it set to this. its probably not perfect but shes not running rich anymore. it took me about an hour to get to this point. what do you guys think?

 

looks like you're perfect

 

Just leave it as it is?

I appreciate all the help you guys gave me, saved me the trouble of buying a new carburetor

 

I can't view the video in work, so I will check it out later.

 

you're good. put the dwell meter away for now. drive it some, keep an eye on your mileage and maybe re-check your dwell after a few hundred miles.

good job

 

so good news, the previous owner of the car and i are still in communication and i was able to get the idle stop solenoid he took off.

i was searching where the wire goes but everytime i get close to a picture i get the stupid Photobucket ransom demand (man i hope they will be gone soon). anyway where in the main harness does the wires connect to?

 

ECM harness. Should come out of the loom that goes over the pass side VC along with the TPS, MCS and CTS conductors.

 

Glad you got that part. And now you know you are looking for the blue wire that was cut.

Solder it! And use heat shrink tubing, not a cheap butt connector.

 

ok guys i have spent the past week looking for the wire and i cannot find it. i pulled all the looms back and the only cut wires i could find is right in front of the passenger valve cover where all the looms go to the main harness. i found 2 solid brown wires, 2 pink with black stripe wires, and 1 black with purple stripe wire. i have the idle solenoid installed with the wire that goes into the harness so it looks functional but since i cant find the wire its not really. i would like to get it working, so what pin on the ECM does the wire go? so i can trace it back from there

 

Looks like "E" to me = Idle Solenoid.

 

Well it seems another problem has cropped up with the carburetor, when im cold starting the car and engage the choke the car runs fine in high idle, but after 40 seconds i tap the gas to turn off the high idle and the rpm drops to 400 and runs bad. Once the engine is at full operating temp shes great, runs at 900 in park and 600 in drive like shes supposed to. Am i turning the high idle off too soon? Im not sure if the choke is properly adjusted, and i dont know what the factory speed for the high idle is. Right now she high idles at 1000-1200 any insight into this would be greatly appreciated. I left work yesterday and all my co workers mouths were on the ground seeing this beautiful Trans Am until i idled her down and they laughed cause she almost died

 

I highlighted your ECM wiring diagram.

Choke could be mis-adjusted. Post a pic.

If you had the ignition turned on for a while before you actually started the engine, the choke coil was being heated during that time. Then when you kicked it down, instead of going down 1 notch on the chokes stepped cam, it went completely off while the engine still needed some choke. Therefore it STALLED.

 

sounds like your choke is coming off too soon. the high idle and choke can be adjusted. you can follow the steps in the carb sticky somewhere up top.

the choke should only receive power when the alternator is running (turned by the engine) this prevents the choke from opening with KOEO and is why the 'choke' light is an indicator of a failed alt.

 

This is how the carburetor is currently. What is the factory speed for the fast idle?

I can say for sure the choke light goes on KOEO but goes out once i start engine

 

Your underhood sticker should say what the fast idle (highest step of choke cam) setting should be. I think something like 2200 rpm.
I could be wrong, but I believe that on my 84 TA, the choke coil gets power with KOEoff.
The starting point for your choke setting is when the notch in the cover aligns with the largest dot (see picture).

 

ok so i turned the choke cover counter clockwise all the way and attempted to start the engine but i think it was too rich cause the engine would not start then she backfired once, gas smell around engine. and fuel vapors pouring out of carb. i turned it back and she fired, ran rough for a couple minutes then smoothed out.

i saw a video on youtube on how to set the choke but i guess that does not apply to the Quadrajet


are you talking about the silver dot on the cover lining up with the big notch on the housing? ill give that a shot and report back. ill set the fast idle to 2200

 

over tightening the choke (within reason-not like cranked half a turn) should have no effect on cold starts. it should only delay the time it takes to open the choke completely.

check your choke pull off. the choke should be completely closed when set with the engine off. once the motor starts and the choke pull off sees vacuum, it should open the choke slightly to allow the motor to run. fiddle with it some and you'll see how it works. you can test the choke pull off by removing the vacuum line, press it in then hold your finger over the vacuum nipple. the pull off should stay in until you release your finger, then slowly extend.

your latest symptoms sound as if the choke pull off is not functioning correctly or incorrectly set. the pull off and choke must work in harmony.

 

the choke plate is fully shut before starting the engine. i even checked the spring tension on the plate and it was good

the vacuum break is working like it should and upon startup it opens the plate a hair to keep the engine running

ill try loosening up the choke thermostat and lining the silver dot with the notch on the housing, and return the fast idle to 2200 then report back

 

this is where i moved the choke thermostat to. car fired right up and i set fast idle to 1800 really got scared turning to 2200, 1800 seemed pretty fast and loud

im noticing the fast idle speed increases shortly after startup as well, is this normal? does it have anything to do with the 2nd step on the fast idle cam?

 

Yes.

Yes. As the engine warms up, the speed will increase. When the car is cold and the choke is on it's highest step, once you start the engine and it revs fast (1800-2200 rpm), give it about 20-30 seconds and then tap the gas pedal. The choke will drop down to the 2nd step of the cam and the speed will be slower. The colder it is outside, this process will take longer to get to your approx 750 rpm idle when fully warmed up.

Your underhood label will tell what to set everything to (assuming it is still there). Attached is a sample.

 

thanks for the sample, mine has been removed before i got the car so im gonna print that out and attach it to the car

 

You should be able to find your exact diagram here: https://www.thirdgen.org/forums/tech...ml#post6155905

 

thanks i might be able to use that

any idea why the car is hard to restart after shutting off for like 10 minutes?

i can cold start normally now, but driving home, shutting off and go to restart she wants to start, but i have to feather the gas until she fires then idles at 400 and slowly gains idle back to 900

i do have a new fuel pump but i did not install it yet

 

Since you messed with your choke setting, I would look there first.
Where is it set now?

 

this is what it is at

the choke plate is also fully open at warm

 

Were you able to hook up the throttle kicker solenoid yet?

 

yes but i think it seized. it does nothing

 

i was able to acquire another remanfactured carburetor pretty cheap throughh someone who has a Z28. i thought could always use a spare carburetor i checked the internals and it looks the factory presets have been changed also the screw plugs are removed.

im thinking they put some glop on the screw as tamper proof seal or something because my carburetor had that on there too

 

Nice. I hope it works right out of the box.

 

so i decided to take the carb apart and discovered the problem. the lean stop screw was threaded into the bore wrong (some idiot installed it on an angle) the threads were stripped so bad it would not tighten down to the 1.304 also discovered the hanger for the float was missing. im pretty much done with National Carburetor after all this crap but in order to save this carb i ordered this thread repair kit
http://www.ebay.com/itm/Tomco-13726-....c100005.m1851
has anyone used it before?

 

Nice find with that thread repair kit. Sounds simple enough.
The float hangar hook is not mandatory. But it does help lift the needle out of the seat should it become stuck in the closed position.

 

Got the repair kit installed though i had to go out and buy a tube of the Loc-tite but no biggie. Got the MCS torqued down and carb back together.

The cam for fast idle was not engaging on the steps so i tightened it down to engage the steps

Also adjusted the vacuum break to open choke plate to just slip a dime through. I dont know when ill be able to try it on the car cause im about to winterize bit when i do ill update everyone on my handywork

 

Good job. It sounds like you are ready to go.

 

i know this thread is rather old but its getting close to a year now and i figured with all you guys helping i wanted to update you all. the carburetor is still running good.

here is a video of the 2018 first start. the car fired right up and im happy with her

i have not driven the car much this year since im have insurance issues (my company doesnt want to insure my car) but ill get that sorted out and she will be going to shows soon but firing right up keeps me smiling

 

 

its been a couple years since i updated this thread but im happy to report the engine is still running like a top. no rich smell, no stumble or low rpm. engine runs great and she drive like she should. only problem im having right now is a code 53 which i believe is a bad EGR solenoid and trying to source a replacement (didnt think that would be so hard but it is)

i still have the spare carburetor and thinking i might just sell it off so someone can use it