I have a 89 RS with a 90-92 L98 in it. Its giving me tons of problems, HELP!!!

For future refrence...
Timing 8* advanced
Fuel Pressure 46psi
TPS adjusted to .88V
Stock ECM & PROM (Gonna get tuned soon.)
Good Vacumn, power brakes work perfectly

My snapon scanner wont communicate with my ECM. My check engine light is on and the car is running like hell. Only engine code I get is #12. Meaning the car wont scan. I have a spare ECM I am going to try tommorow on it see what it does.

It will either idle like crap and have good high end, or idle ok and hesitate up top.

The car runs very very very poorly when the timing connector (tan/black wire) is plugged in. I have it timed to 8* advanced and while I was timing it, the timing was bouncing 4*. (Between 4* and 8* advanced.) It will run like I mentioned before with the connector off. I tried timing it with the connector on and mostly by ear, it had good power, but backfired through the exhaust. (Turned out to be 30*, so I backed it back off to 8* with connector off, car sounds like its extremely retarded.)

When I rev the car, unburned fuel shoots out the exhaust. It acts like it has a huge vacumn leak. But I sprayed everything down with carb cleaner, and nothing. When I shot it through the throttle body, it picked up. The hydrocarbons shooting out the exhaust make your eyes water too. It acts like it has a lean miss, but its shooting fuel out the exhaust.

Sorry for my post being all over the place, this is driving me nuts and my brain is working kinda slow today. I am kinda thinking its between the MAP sensor and the ECM together. When I unplugged the MAP sensor, nothing changed on the car.

 

Try setting ur TPS to .54 volts, That will help alot.

 

It wont adjust that far. Spec is also .36-.96v. I have to grind more to get it farther.

 

Sounds like you might have wiring issues if you cant scan it. Right from that, I wouldnt trust the code 12 too much besides that the ecm is saying "Yes, I'm here."

TPS is WAY too high. You need to get that below .6, preferably around .45v

 

Its a brand new Painless wire harness.

 

Then I suggest you check the wiring.

It's a SD setup? Make sure your ALDL pins are correct, chances are its wrong.

 

Yes, SD.

I have 3 series of problems with this car.

The Harness comes with a stand alone ALDL connector. For the hell of it, how many wires are supposed to be there? I think I have 4-5. I also replaced the computer with a spare I have and I still only get code 12 and it wont connect.

The car running like ****....well, I turned the TPS to .56v and it helped the idle, yet the car still falls down on the top end. I am starting to think its a timing issue. The only way the car runs halfway decent, is with the timing connector off. When its on, the timing gets so retarded the car stalls out. I cranked the timing up on it, and the car ran great up top. I am starting to think something is messed up with my Knock Sensor. It might be detecting false knock and retarding the hell out of my timing. But since I cant connect to the ECM, I cant tell. I'm just gonna unplug that, connect the timing connector and see what the car does.

My cooling fans wont work unless I jump the wiring on it. While its a PITA, its not critical at this point in time.

 

I know the harnesses, I've dealt with them. Many people say they are easy, well made, etc etc... I disagree. About the only thing they do IMO is give you new wires and new sensor and ECM connectors.

Check your ALDL pins. Probably do a search for the ALDL connector or find a wiring diagram (you do have one, right? I wouldnt step any further without one) and verify that the data stream wire is in the right location... I'd rather not make a guess right now and be wrong. I'd bet its not in the right spot though, mine wasnt. Without that wire in the correct location, it'll never connect. I'd also make sure you hooked up the right wires under the dash to the "Painless" harness.

 

Code 12 only indicates "no distributor input" to the ECM. This is of course OK because you usually check for codes without the engine running so this is a logical code to get.

 

I have access to Alldata, I have the original book from Painless, and I have the factory manual. I will check into that tommorow.

 

Code 12 means diagnostic mode, and if your scanner is picking that up, then it is communicating with the ecm. However, there might be another problem. Try to manually pull the code by jumping the a and b terminals, and reading the codes flashed by the engine light. 12 will flash 3 times, then each code after that will flash 3 times... once thats done, it will return to 12 and start over again.