1991 olds 98 no injector pulse Help!

[zeeman216]

I have no ground at all 6 injectors. I have key switch volts on all injectors. I was told that the driver in ecm sets the ground for all injectors.
I replaced the ecm, crank shaft position sensor, cam shaft position sensor, C3I module, and coil packs.
Also, check engine light dose not luminate.

[Jrs3800]

Have you checked the body grounds inside the car to make sure the ECM is getting the grounds its needs?

98 is the newer body for 91, so it will actually have a PCM..

[Mechanical Mike]

A faulty throttle position sensor could cause the PCM to go into 'clear flood mode' & not ground the injectors. Try unplugging the TPS.

[zeeman216]

Thanks for getting back so quick.

- We did check the body grounds. We weren't sure where they were at first so we pulled out the seats, carpet and installation in order to find them. The car has had water leaking into it and we though that might be causing a problem with the grounds. However, even though there was some rust from the water on the floor we didn't see any grounds on the floor. We did see some grounds a little higher up on the kick panel but they appeared to be clean and tight. If you know of any other grounds please let me know.

- We will check the TPS and get back.

Note, the car has 294,000 miles on it and ran great prior to it just shutting off while sitting in line at a Mc Donalds drive-in. I would hate for it to end that way!

Thanks for the help.

[Jrs3800]

Really stupid question and I am sure I am reaching... Did you install the Mem-Cal in the new PCM? Was the PCM brand new or a Junk Yard unit? Just trying to rule everything out...

[Mechanical Mike]

I don't believe the TPS would cause the car to stall but I'm not 100% sure. I'd still try unplugging it.

Is the PCM under the dash on the passenger side? If so then the grounds are probably on the passenger side ground bus. I'll add some pics ASAP.

[Jrs3800]

It wouldn't cause it to stall... But if it was at 100%( Dead TPS ) then yes the PCM would not allow fuel pulse..

[Mechanical Mike]

[zeeman216]

Not sure how the ECM is different than the PCM. Is the PCM the body control module?
We did get a new(different) computer from the junk-yard, it had all the same numbers, however, there were four letters at the end and the fourth letter was different. We changed over the PROM from the computer that had been in the car to the one we got from the junk yard and the installed the computer. The car still didn't start. The computer is located on the passenger side.

We will uninstall the TPS and try to start, however, the battery is dead right now and we have to charge it. I'll get back later today.

[Mechanical Mike]

ECM (Engine Control Module) & PCM (Powertrain Control Module) are basically the same thing, the computer. ECM became PCM when they started controlling transmissions as well as the engine.

[zeeman216]

I appreciate all the help you guys are providing.

We did not know about the ground bus on the passenger side nor the drivers side they had been wrapped in tape. With the help of Mike's pictures we found them. The drivers side ground bus had turned green and had rusted presumably from the water leakage, the passenger side was not as bad. Since the PCM is on the passenger side I assume the passenger side ground bus was the important one for the injectors. We cleaned up both ground buses and tried to start the car, it still cranked but didn't turn over. We checked the six injectors and they still were not getting a ground. Are there any other grounds we could be missing? Because of all the water that leaked in the car over the years I think this is where the problem lies.

We had to get yet another battery from the junk yard, we were able to charge this one. We disconnected the TPS, unfortunately the car still didn't start.

We have had some problems lately with batteries in the car, the battery I had in when the car originally shut-off was not that strong and the three batteries since then all seemed to have a problem holding a charge. We are starting to think we may be having an additional problem with the starter motor. Can you guys think of any link between the ground problem and the starter motor?

Again, thanks for your help, we appreciate it.

[Mechanical Mike]

Did you check for spark? A bad crank sensor would prevent both spark & injector pulse.

[zeeman216]

I did check 4 spark it has spark. I cleaned those ground bus bars and check them with my test light to power supply, light lit when i tuch the bars..I unpluged injector again and test probed the pink wire it has key switch volts i reversed test light to bat power checked 4 ground and no ground when u crank it i checked each ground wire from injectors with ohm meter back to ecmall ohm good.

[zeeman216]

O by the way i did replace crank sensor & cam sensor iam wondering about the magnet on the timing chain if it fell of would there be a injector pulse?

[zeeman216]

Also the check engine dose not light, I switch the bulb with a known working bulb, Is this somting i should look into?

[clm2112]

O by the way i did replace crank sensor & cam sensor iam wondering about the magnet on the timing chain if it fell of would there be a injector pulse?

Yes, the car will still pulse the injectors without a cam sensor. It will throw an error if it doesn't see the cam sensor, but will still run the injectors. The pattern will not be in sync with the actual opening of the intake valves, but it will still be there.

Spark comes from the ignition control module under the coils. It is an independent subsystem, so you will get spark even without a working ecm (or pcm). It also indicates that the crank sensor is working, since that is the timing on the spark.

Start with the check engine light. Make sure the bulb is good and you get the light with key on. If the bulb is good and still no light, you have an electrical problem at the ecm that needs to be solved before getting anywhere else.

You've tried two ecms already (the original plus a junkyard unit.) To me, that also points to a wiring issue. I would break out a voltmeter and start checking circuits to make sure there is power to the ECM.

[zeeman216]

Thanks for getting back 2 me! I will remove the cluster tomorrow check bulb. I think bulb is ok i`ll check 4 key switch power 2 bulb . The other side of socket should have ground ? maybey it gose back 2 (ecm) & when it starts it gos open if thers no errors in (ecm). Does any body know what wires on data link connector should be hot and witch leters should b groundi think there is no communication issue also? Thanks Dennis..

[Winn]

My 92 wouldn't start /run last year. Spark, no fuel pulse. did extensive voltage test at computer. Solution, mouse had chewed insulation off of one of the battery leads in the firewall fuse box (one of two to the computer). corrosion. corrosion would carry enough milliamps to activate voltmeter, but not circuit to run fuel pulse. Cost.... hours of hunting, $0.30 butt connector.

Winn

[zeeman216]

Thanks Winn, I have 2 fuse blocks on my firewall one is on driver side the other is on pass side wich one do you mean ? The one on pass side dose have inj, fuse ! I did remove myspeed cluster and was unable to gain acess To my check engine light while gang connetor was in place to test for 12 volts at socket while key is on ,I exchange bulb with known working one and still wont light when key is turned on! Does anyone know how to check this service engine light circuit ?I think this might have somting to do with my cars no injector pulse or ground at injector .Thanks guys you have been a grate help!!!