kibs45

I have a 1990 100Q. I have been having problems with the car stalling. So far I have replaced the following: all vacuum tubing, injector "bushings" and seals, idle air control motor (this was cleaned as well and verified working), idle and wide open throttle switches (also verified working), fuel filter. When the system is completely hooked up everything seems to function well together, ie when the idle switch is closed the idle motor receives signal from engine control etc... What is strage is the car runs fine when the idle switch is disconnected but when the switch is connected once the car is idleing down it will often times stall, if I feather the throttle I can get it to idle at the appropriate speed but it is rough and lumpy. I recently checked the duty cycle of the differential pressure regulator and it is roughly 50% when not hot and 99.9%-100% when completely warm. The only thing I can actually tell at this point that is actually still not working is the o2 sensor. It maintains 38-42 mV at all times. Honestly I am just not sure what else to do. I took the car through emissions today and CO was reasonable but a little too high, however HC was way way too high. Apparently the car is running rich. Anyway if anyone has any thoughts or an experiance like this I would really appreciate the help!
Thanks,
Joel

paulfern2000

I had the same thing on mine last year.
I figured out a quick way to check this.

while having someone inside to help keep the car at some sort of reasonable idle...tap with a hammer on the fuel distributor..if the idle changes or improves ...your fuel distributor is shot.

mofologic

my 91 100 did more or less the same thing and it turned out to be a rip in the hose from the ISV to the IM

kibs45

When I had the top half of the intake manifold off I checked all the hoses they are good. There are no codes in the computer except the one for the O2 sensor. As long as I don't make the car "catch" itself it will idle all day long just not real well. Thanks I could use all the help.

rooster 2

I helped a buddy change his 02 sensor in his 87 5K when it wouldn't idle right, and driveability was bad. Changing the 02 sensor completely fixed the problem.

In my opinion, fuel distributors don't break very often, contrary to what others have posted.

kibs45

Its old I don't know how old, I know that it is not cycling (it has failed) and the engine control blinks out a O2 sensor code. I just didn't want to drop the money on what I assumed was just emissions stuff until I knew it would idle, I guess I will be giving it a try. Thanks.

kibs45

So I need to take a refresher course in starting with the small stuff. I went to ohm out the coil wire and the car has the wrong wire in place. One end has the wrong plug and does not snap into place. I have temporarily tweaked the wire and it makes a huge difference. I will put in a new correct wire tomorrow. I will update with more info later. I am very suprised the car ran at all.

kibs45

New wire end in place and car runs fantastic! Idles much better and no stalling. Thanks for all the input! Unfortunately it looks like I need a new coil though due to lots of arcing in the current coil.