I was wondering if anyone knows if I can use a vacuum advance HEI on a 1985 V6 engine with EFI. My ignition system seems to be fubared and Im trying to figure and easy way to just fix it so I can drive the damn thing.

 

If it has EFI, not easily...

The advance would have to be locked out.

 

Dammit all this frustration with my EFI is not worth it. I shoulda went carbed, atleast my father knows how to tune a carb.

Well is there a way I can lock out the advance so I can make it work? Everything else on the car functions as it should, but the ignition has no spark. I checked for voltage at the 12V key on ignition feed wire and I get voltage.

 

EFI is easy to diagnose and repair, once you stop thinking of it as electronics and a mystery box.

Start with the basics...

You say you don't have spark, do you have injector pulse when it is trying to start? You can use a "noid light" or test light jumped across the terminals of an injector to know.

If you're not, I'd say that the Ignition Control Module might need replacing. The ICM is a very important part to getting a GM EFI system to function, it not only controls the actual spark, but also sends signal to the ECM that the engine is actually turning over and at what RPM it is, so that it can control all of the functions it needs to.

Just FYI, with a properly functioning ICM and ignition system, the EFI dizzy system will still provide spark with no ECM attached to it.

Even using the vacuum advance dizzy that you propose to do, would still require the EFI ICM to get the car running.

 

Well the entire dizzy was replaced including the ICM as my old one was cracked. I verified the dizzy was receiving power from the red/pink ignition with the key in the on position. I verified this at the coil itself and then at the feed line that goes to the dizzy. Thats where I got stuck. I did not test the injectors however, but it should be sending a pulse (correct me if Im wrong) but the engine is definitely receiving fuel as the rail tells me I have pressure and the engine started flooding when I cranked it.

 

Is the coil receiving a signal from the ICM?

It could still be a bad ICM, or possibly bad coil.

 

How would I go about checking this? Im not positive. I only checked the ignition wire that goes to the coil, and then the one from the coil to the ICM and they have power. Both are red/pink wires that I am assuming carry the power.

 

Use a DMM set to AC voltage, attach one probe to ground, the other to the negative terminal on the coil, crank the engine and you should see about .5 to 1V AC during cranking.

 

Ok I will try testing the coil tomorrow. I unfortunately have no time today because of some online stuff I have to get done for college. Hopefully ill get this thing figured out so I can drive it.

 

This is what you need to fire the coil, all you need is a test light to test it.
The red wire should have power when on & cranking, test it that way.
The other wire (neg side of coil) should have flashing voltage when cranking.

 

I tested the coil today. The red wire has power going to it. The ground side of the coil itself has no flashing pulse what so ever. I tried swapping the coil out for another one and I still get no flashing pulse. The red wire still has power though.

 

The ICM, or possibly the reluctor are bad. If the injectors are actually pulsing, then I would say the ICM is bad, since that would indicate that there is a pulse getting to the ECM, which comes from the ICM, that is triggered from the reluctor.

Check for continuity of the white wire from the ICM to the coil as well, before doing anything else.

 

I will check the injectors tomorrow to confirm they are sending a signal. The white wire from the ICM to the coil is continuous. I made sure the wires were ok there. Is it possible that the ECM might have gone bad?

 

Like I said before the ECM can be removed from the car and you will still have spark with a properly functioning ignition system.

 

Ah I kinda forgot about it and didn't give it much thought. Now I am more positive about trying to get my car running as dumb as that migh sound lol. Thanks for the helpmso far. I will test the injectors pulse tomorrow.

 

Well I took a look at the car today and it seems that the rear cold start injector connector is broken. Will this affect anything? I thought it was independent of the system. As for the injector pulse Im still not sure, since I misplaced my multimeter and it was freezing cold today. Im gonna have to check for pulse on a day it isnt poruing down rain.

 

Ok so I checked for injector pulse today. It indeed has a pulse. I decided its probably just a bad ICM that I got from the store in the in the new dizzy. So I just took it back. Now I have to wait till thurs to get it and install it.

 

Ok update: I GOT SPARK YES! ICM was bad and was replaced now the car starts. But as soon as it starts up the idle jumps to 3k rpm. Any ideas on what might be causing this? I need to test TPS tomorrow. Im just happy my car starts now though.

 

It might need to relearn to idle, but make sure you have no vacuum leks or loose connections.
Yeah, tps out of adjustment can cause high idle.

 

Ok so today I went outside and repaired all the vacuum lines and made sure they are all secured correctly. I also made sure the EGR valve was sealed. Anyhow I started it up. The car wont stay running now. It starts up and just dies immediately afterwards. I think one of my sensors is wonky. Any ideas? Just found a thread on how to adjust TPS. So I will adjust it tomorrow. Are there any other sensors that I should check to for issues?

 

You need a volt meter, you need to back probe the wires at the tps to adjust the voltage. Search here or get a manual, it'll tell which wires.

 

I just found a thread to adjust the TPS. I have a digi multimeter tht I use on my jeep all the time. I read that Im suppose to backprobe it at the middle and topmost wires and should set the voltage to .55 +/- .05 volts? If this is correct I will be doing this tomorrow. Is there any other sensors you would suggest I check? My engine isnt throwing any codes as I tried the paperclip trick already.

 

Yeah, thats where I'd start.

 

Just adjusted the TPS about an hour ago. Car seems to run a tiny bit better but wont stay running worth a damn right now. It crank spark, run for 15 secs and die. I checked fuel pressure and verified it is good and correct. Does anyone have a vacuum chart for an 85 firebird? The original one for the car is nolonger there and all the vac charts I find are for a camaro, which is what I used, but I just want to make sure that isn't my issue. Anyone have ideas?