I got a L69 with cc quadrajet in a ex LG4 87' Firebird with its L69 ECM and stuff.
Cause of headers I got a heated O2 sensor, as the stock wasnt getting warm enough for good readings.

Since short the car is running rich (as you can smell it) and today on the highway in traffic jam it threw me error code 45 - running rich.
Nearly died some times.

Strange thing is that sometimes it feels like there is no power and sometimes just runs normal.

In the past the qjet had its problems and was rebuilt already.

Car runs little little rough in idle and I mentioned that in idle the RPM are moving 200rpm up and down slowly sometimes when the engin is warm (like 500rpm - 700 - 500 - 300 - 500..)

I measured out thr TPS and the volts are just as they should be.

Any ideas what to check now?

 

I just had the same issue with mine. Have you checked the Mixture Control Solenoid on the carb? When the key is in the "ON" position, you should here it clicking. It'll do this for about 20 seconds then quit if the car isn't cranked within that period. When started, it'll click continuously. This is normal operation for the MCS. It's the only other thing stated besides the O2 sensor that should cause the mixture to be rich. Of course, the O2 sensor you installed may not be any good. It happens. It could also be an intermittent O2 connector or MCS connector, too, or possibly the wiring for either.

With the varying idle RPM's, it sounds like it's hunting for the right mixture. Of course, the O2 sensor tells the ECM what the air ratio is in the exhaust, and the ECM adjusts the mixture, accordingly. I replaced my O2 sensor with a stock sensor, and it changed from running rich to running lean. I discovered that I had other issues with the carb. (Car sat for 12 years, and now, the carb is suffering from carb death. It needs to be rebuilt.) In the beginning, I suspected that the O2 sensor was shot, and apparently, I was right. What I learned is that, with a bad O2 sensor, my engine ran rich. When the ECM got a decent signal from the O2 sensor, things changed.

If you're sure your MCS is working, then I'd suspect the O2 sensor. Like I said, it's possible that you got a dud. Either that, or start looking hard at your carb.

Also, I'm not an expert, so if anyone else has any other ideas what's happening, I'd be happy to hear what anyone else has to say because I'm learning, too.

 

thanks for the hint.
I hear it clicking and I already measured out the voltage before and it was good.
I just read in an other thread, that the OHM should be measured too when its warm (not cold, not hot, just warm) I will try this also tomorrow. maybe its bad ?

I try to read out with a friends ALDL Cable the Computer what it reads, then we will see what the O2 Sensor says.

Thanks!

 

The ALDL thing will have to be tested next week..
Today I figured out that the plug that goes on the electric choke seems to be bad (its broke) and was not sitting properly on the electric choke.

The choke light was off all the time. Now the choke light goes on.
I guess that the not fully open choke could have caused this, heh? what do you think

 

Just found this video:

he says a car running rich when the O2 sensor is suspected to be good, the first thing he would look at is a vacuum leak.
I just tested with a vacuum gauge my car (https://www.youtube.com/watch?v=KWJI...ature=youtu.be) but it seems to be good? stay stable.
I will try the thing with the gas test he is doing tomorrow

 

I doubt the choke not being connected was causing the problem. Mine isn't connected, and I threw the same code. Typically, if the choke light is staying on all the time, check the alternator. There's a recent thread on this: https://www.thirdgen.org/forums/carb...ml#post5778126

Also, you don't need a code reader to read the codes on a third gen. Do a search of reading codes using a paperclip and shorting out two of the pins on the ALDL connector. Yes, it works because I've done it. That's how I read my codes.

 

Thanks thats good to know

Thanks, I already startet reading some of those threads. I am just wondering as it loads really great. I started a thread with the wiring, as I have seen that I use a two wire altenator and a third cable is hanging loose there.

Thanks for the hint with the paperclip. Thats how I got this code out of the system. But i wanted to check the O2 readings without hooking up to the O2 Wire. With WinALDL you see even more and I wanted to troubleshoot this way.

 

I hear ya. I have an Android phone, and there's an app (ALDLDroid) that I want to use to troubleshoot and tune. The app page references a bluetooth adaptor that plugs into the ALDL port. This way, I can see everything happening on my Samsung S5 while tuning or driving.

 

ok ok ok... we found something new


TPS checking on the carb is ok.. voltage as it should be
but on the computer I receive only 0.000 volt and when I disconnect the TPS its 5.000 volt

seems to be a short circuit somewhere ?

oh and by the way.. the MCS clicks but does not stop? in the past it did stop. now it just stops after car is started

 

If the TPS reads good with a DMM, then there's something going on with the data stream. I'd guess possible ECM issue.

The MCS usually clicks for 20 seconds when the key is in the "on" position. Then it will stop. Once it goes into closed loop, it should start, again.

 

ok.. i started over and measured again the TPS itself, as I said some posts ago, I did recently measure it and it was in spec.... ..... ..... but today it just did 5volt all the time.
so the tps seems to be the last faulty part

I dont know why, but today the MCS clicks for the 20 seconds... last time when the car and engine was warm, it did not stop clicking,.. dont know if thats normal?

tomorrow I will swap the TPS and see if its good again.

when the tps is disconnected, should there be a reading on the blue cable ? (+ white, voltage measurings blue, - black)

thanks for your help

 

When you check the TPS voltage, you're supposed to connect the DMM between the B and C connectors using jumpers while the TPS is connected to the ECM. With the engine off, turn the key to the "On" position and read the voltage. With the throttle closed, it should read what the spec value is. The weather pack connector is labeled A, B, and C. The B and C wires are the bottom two wires. Do not measure at the A connector.