1990 Buick Century Repair Question
Ac randomly stop kicking on. But with Ac fan or heater running I think my car runs a bit better. Not quite sure could be my imagination. Noticed that when driving awhile my car wont reach full 190 operating temp(witch it uses to.) Codes have 26 and 27 Quad-Driver (QDM) Circuit. Think because I have the toque clutch converter unpluged because it was haveing problems dieing when I stopped after going 55mph(shutting stop kinda like stopping in a manual and no pushing the clutch)
What has been replaced. Iac,maf,spark plugs and wires, ECM, o2 sensor. The iac when replace I heard if you plug it in and turn the key on or try to start it you could see the pendle moving in and out. I did that but the pendle did not move so I'm thinking about testing the wires but I don't know what wires go to what there's 4 coming off the iac. Thank you for any help.
Symptom indicates multiple problems and the main one is to get the codes resolved. You should plug the TCC solenoid back, erase the trouble codes and check if the codes come back. With trouble codes present due to a fault in system, the engine performance would be affected.
You mentioned the accelerator can only move an inch or so, check the throttle cable adjustment. If you have too much slack, the throttle sowould not be able open fully during ful throttle and that is the cause of lack of accelerating power.
The engine engine not increasing in rpm during cold starts could be due to a faulty idle control system and the IAC is the main item to check.
Have you checked for vacuum leaks between the MAF and throttle body?
Do you have coolant losses issues?
When you are unable to restart at operating temperature, you need to find out what is missing causing the non starting. From there we would be able to ascertain which circuit to look at.
The codes go away when I plug it in but when I do that I can't drive 55 with out the tcc locking up and me having to unplug it to drive any farther. I can't really afford transmittion work. But they say its fine if you leave it unpluged you use more gas and don't have over drive. Are you talking about the throttle cable going to the tranny. Because I have replaced it but I can try adjusting it. The iac do you have the wiring diagram so I know what wire goes to what so I can test them with one of the light testers. I want to check for vaccum leaks but I don't know the correct way. Something to do with carb cleaner. Can I use maf cleaner to check? I no coolant lost but I do have a tiny hole in top of radiator but doesn't seem to leak and only smoke once.
Cable to trans and throttle body have to be adjusted correctly.
If you have a hole on top of radiator, how is it that you don't have coolant losses?
If it is the TCC that is locking up causing the problem, it should not a transmission internal fault. It could be the controls or a faulty solenoid.
You can use MAF cleaner for checking vacuum leaks.
Attached is the IAC wiring.
Okay well I'll mess with the cable tomorrow and let you know
I don't know but every time I open the radiator cap it's filled completly to the top. I shake it to make sure no air bubbles. But it has only smoked once and never again I guessing it's just a tiny hole
The tcc selinod is also in the tranny but I heard on my car it's just on the other side of the side pan. And I can remove the side pan without pulling out engin or jacking it up
I'll look for leaks tomorrow too. Thanks for the diagram
Yes, you can access the TCC solenoid by removing the oil pan but you should not attempt to do so until you have diagnosed and cofirm it is necessary to do so.
Don't mess with the throttle cable. It has to be adjusted correctly to work. Ensure gas pedal cable does not have excessive slack.
1. Engine must be off. Depress metal readjust tab on cable adjuster (located at cable support bracket on engine) and hold it in this position.
2. Move cable housing slider (away from throttle lever) until it stops and is completely against fitting. Release readjust tab. See
Fig. 3 .
3. Rotate throttle lever (by hand) to its full throttle position. Slider must move (ratchet) toward lever when lever is rotated to its full throttle position. Check cable for sticking and binding.
Well I did some googleing like I always do trying to figure out whats wrong. Came across a page saying a icm ignition control module can cause dieing at operating temp and not starting till it cools and hesitation. So I took the part off and took it to my local autozone and it failed the test. So I'm thinking that's the problem with my car. Could the code 26 and 27 quad driver circuit be the icm?
Yes, they are linked.