I just got done installing my radio and now my cars stumbles and sometimes dies when you first start it up and get going around 20 Mph it will stumble and after a few seconds it will come back and run fine untill I shut it off and then it does it again when I restart. I I push the gas when its happening it will bog down. I thought it was the Ignition Control Module because I left the key in the on position for hours on end doing the install with a battery charger on it, so I changed it and it ran great for about 3 miles then I shut it off and when I restarted it a hour later it wouldnt idle and died a few times and stumbled again at around 20 mph. Could I have fried the coil too? What else could it be? The car ran great before the install so I think it has to be because of me leaving the key on and a battery charger hooked up. This is a 1990 RS with a 3.1L V6
Update: 5 minutes after posting this I went to go get a new coil and the car didnt do it once so I'm going to change the coil since I have it and see what happens but I would still like to know if you guys have any ideas?

 

Check your power and illum wire to the radio. Either that or the gound isn't solid to the radio. I don't believe it has anything to do with the coil. Something is touching and grounding out the car.

 

As far as the idle if the car lost power the IAC motor might have to relearn its idle speed. I would unhook the radio and see what happens.

 

I have checked all the radio wires and when I installed it I used a harness adapter after I fixed the old harness that was cut. I just changed the coil eariler today and so far it has not done it so maybe I did fry the coil and ignition control module when I had the key on for so many hours. Its weird it only happens at around 20 mph and only on the first time you reach 20 after you first start it then its fine untill you shut it off and restart it then it does it again an 20mph. Remember this is the car that is stumbling and dieing not the radio.

 

Well I thought I had it fixed with a new coil , icm, and plugs ( the guy i bought it from had the wronge plugs in) I drove it all day and just now it died on me twice and then decided to start and go. Any Ideas on what to check next?

 

The Radio instal has NOTHING to do with the car stumbling, so checking those wires and connections will only serve to waste time.

Do you have any codes popping up (Check Engine Light)?

Doing the basic checks, like how strong the spark is, how much fuel pressure you have, make sure the exhaust isn't plugged (I.E. clogged cat), clean the TB and IAC passages, etc, will reveal the problem.

BTW, if you want the key on, to have power at the radio, without the engine being on, turn the key backwards, from the lock position. This doesn't apply any power to the ignition system.

 

I dont have any codes and last night it did not want to start so I'm going to check fuel pressure and spark today. My ignition doesnt have the acc position and thats why I was using the on position, I think either my lock cylinder or switch is messed up. Could a bad ignition switch be the problem?

 

Did you use grease under the icm???

 

Yep I used grease. I just got done checking and heres what I found I have really good spark off the coil and plugs, my fuel pressure is 45 psi but when I went to check the injector harness I got 4.5 ohms on one bank and 1.5 on the other my manual tells me that a injector is shorted. My scanner says the computer is pulseing them on but It still wont start. I can get it running with starting fluid so I know its fuel related so I will pull the plenum off and check each injector and harness and let you guys know what I find. If anyone has any tips or ideas please let me know. Also does anyone know what the single injector resistance is supposed to be I cant find it in my book? All it says is each bank should be around 4 ohms and not over 6 or under 2, but what is the single resistance?

 

Around 12 ohms.

 

Heres my resistance readings for the injectors
1 12.4
3 12.4
5 12.4
2 2
4 11
6 9.5

It looks like my number 2 injector is dead but I'm not sure about 4 and 6 Does anyone know the minimum and maximum resistance for the injectors? Also would having just one injector shorted cause the car not to start? Could it have blown out the computer too?

 

Replace 2, and 6, 4 should be fine.

Yes, having one injector that low can shut down the injector drivers down, so that the car would not start. The ECM may or may not be damaged. Replace the known problem (the injector in this case) and then if there is still a problem work back to the ECM.

Leaving the key on for a few hours could have caused this.

 

OK I'm going to replace injectors 2 ,4 and 6 and see what happens. It will take me a few days I dont have the money for new ones so it looks like I'm off to the wrecking yard with my dvom to find me some good ones. I will let you guys know how it goes.

 

OK I think I got it fixed I replaced injectors 2 , 4 , and 6 with some ones that I pulled from a 1990 lumina 3.1 at the wrecking yard. The part numbers matched and they measure around 12.4 ohms each so they were better then what I had. Anyway I put new o-rings on them, put the manifold back together and it fired right up. I will let you guys know if I have any more problems.