Help! 1991 C4 rough idle and stall

[dabailey2]

My 1991 has about 110k miles on it. I was driving it about a month ago and as I was about home (after driving about 50 miles) I was at a stop light noticed that it was idling a little rough as if it was going to cut off but not but then if i put it in park or neutral it ran smooth, so then I started to take off from the light and i noticed that it started to stall out like it didn't want to go the after about 30 seconds it would get up to speed and seemingly run fine. I got it home and parked it without really putting a lot of thought into it. about 3 or so days later I got in and it started right up, I drove it about 30 miles with no porblem so i thought it was okay. later that same afternoon got in it and drove about 20 miles then as i was slowing down at a light it cut off. It started right back up and then the rough idle and hesitation started again. This time it was much worse i tried to go about 5 more miles but it continued to cut off and the performance got worse. I after it cut off about 2-3 times and started right up on the first try, it cut off nad would not start..almost like it was flooded or not getting enough gas. let it sit for about 2 hours tried to started it, it started right up and i thought it would be okay to get home, drove fine for about 1 mile and then it started again. Changed fuel filter, fuel pump, strainer, spark plugs. Fuel injection pressure is within spec all the spark plugs fire. Still having the same issues

I have noticed that the battery charge light is on and the battery dies and this all started when this issue began. If i start the car now the right side of the engine gets hot to the touch but the left side does not, although it is not working but all the plugs fire on that side and they are not wet or anything. There was a wire next to the fuel injector that was a loose but when I hooked it back up the battery was dead so dont know if that did anything.

The speedometer went out about 2 months ago and I know that can effect performance but not sure how. Any ideas? I am stomped.

 

[sstearns2]

Sounds like the alternator died. New alternator and battery. It sounds like you have more of a problem than that. If the battery is so low that the engine stalls, then it shouldn't have enough power left to turn the engine over.

My first thought is fuel injectors. If they are original, then they should be replaced. If one goes out then the engine will run rough, once two go then engine stalls. You can check the fuel injectors by unplugging them measuring the resistance between the two pins. If I remember right it should be 16 ohms. I used 'rebuilt' injectors on my 1990, $250 for the set and it's not that hard to do yourself. Lots of threads on fuel injectors.

Cheers,
Scott

 

[dabailey2]

Thanks Scott,

Would the injectors go out "all of a sudden" or is it a gradual thing? Would that explain why only one side of the engine seems to be functioning? Like I said, the right side you cant touch without burning yourself but the left sideis barely hot after letting run for a few minutes.

 

[gmjunkie]

Welcome to

Thanks Scott,

Would the injectors go out "all of a sudden" or is it a gradual thing? Would that explain why only one side of the engine seems to be functioning? Like I said, the right side you cant touch without burning yourself but the left sides barely hot after letting run for a few minutes.

It's usually a gradual thing,but there Batch Fired and 1 shorting will effect the other 3 on the same bank!! But so can other things too!
From your symptoms,you have other electrical problems that can cause that too!
How bout the MIL(Malfunction Indicator Lamp) is it lit up??

 

[dabailey2]

No other lights on, I and about 99% sure that the speedo issue is due to the speed sensor on the transmission tailshaft. Occasionally the check engine light comes on if I drive for a while due to the speedometer and tach, I was told that there the car could run bad if the speedo is not working because it is not giving the correct signals to the engine...or somethign to that effect....but the speedometer has been out for a few months now and because its not my main car I have just never gotten around to fixing but the car ran great for a couple of months with the speedometer issue, just wanted to make sure that these were not linked togerther. The only other light that comes on now is the battery charge light and that started the next day after the stall/idle issue. May be due to the trying to start and what not but then not letting it run long enough to "recharge" I will check the IAC tonight, other than that I am running out of ideas.

 

[sstearns2]

Pulling the throttle body and cleaning it and the IAC is something that should be done just for general maintenance. If the IAC is really gummed up it can't move to control the idle very well.

It's amazing the eninge is running if one whole side of the engine is cold. Let us know what the resistance between the injector pin is.

Scott

 

[Schrade]

What exactly was fuel pressure? Under what conditions? It needs to be done static and dynamic.

[ME]Fuel pressure needs checking static (motor off), including pressure leakdown time, in 15, or 30 second increments (write them down), and idle with vacuum ON FPR, idle with vac OFF of FPR, and pedal down, on the road.

Vacuum makes pressure increase for enrichment, and INcrease vacuum makes FPR reduce fuel rail pressure...

Occasionally the check engine light comes on if I drive for a while due to the speedometer and tach ...

Why do you think it's due to the speedo and tach? Do you know the paper clip scan method?