Engine miss

Tiny
TOBYJAY
  • MEMBER
  • 1994 OLDSMOBILE DELTA 88
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 88,000 MILES
I have one cylinder on a V6 1994 Oldsmobile 88 in which any fuel injector will not fire. I have verified spark and whichever injector I put in that cylinder does not fire.
I get a 12v reading at the injector harness at every injector. Is it reasonable for me to assume that the problem is with my engine computer not providing the appropriate pulse to that particular cylinder?
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Sunday, March 6th, 2011 AT 4:13 PM

52 Replies

Tiny
SATURNTECH9
  • EXPERT
So one cylinder the injector won't pulse?If so which number cylinder?So you have power to that injector?All the other injector's pulse and work?Let me know.
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Sunday, March 6th, 2011 AT 4:28 PM
Tiny
SATURNTECH9
  • EXPERT
Do you have a test and multimeter to do some testing?
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Sunday, March 6th, 2011 AT 4:29 PM
Tiny
SATURNTECH9
  • EXPERT
Test light I mean.
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Sunday, March 6th, 2011 AT 4:29 PM
Tiny
TOBYJAY
  • MEMBER
Saturntech9 - I have a multimeter. The cylinder in question is the front right cylinder. There is voltage going to that injector.
All the other injectors pulse. A lasor temperature gun shows low temp at the manifold of only this cylinder. Whichever injector I switch with this cylinder does not activate. I can hear the other injectors bt touching a long screwdriver at the base of each and placing against my ear. The front right cylinder has no injector sound. Tobyjay
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Sunday, March 6th, 2011 AT 5:04 PM
Tiny
RASMATAZ
  • MEMBER
Test that cylinder ground driver circuit back to the computer
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Sunday, March 6th, 2011 AT 5:09 PM
Tiny
TOBYJAY
  • MEMBER
Would a proper test be to connect my voltmeter between the grounding side of the injector plug and the positive side of my battery while cranking the engine with the ignition disabled?
If the trigger pulse is working I should see a jumping voltmeter.
Is this the correct method?
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Sunday, March 6th, 2011 AT 5:16 PM
Tiny
TOBYJAY
  • MEMBER
It appears my digital voltmeter does not respond fast enough to see the fluctuations in voltage from the trigger signal. With the ignition disabled, each injector, including the suspect cylinder,
shows the same steady voltage from battery plus to the injector ground terminal when cranking the engine. I'm now looking for an analog voltmeter to see if that will help me see the trigger signal. Razmataz or Saturntech9 - Am I going in the right direction?
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Sunday, March 6th, 2011 AT 6:22 PM
Tiny
TOBYJAY
  • MEMBER
For what it's worth here's what I saw when I used an older voltmeter
with a needle. With motor running - rapid voltage fluctuations (trigger signal) on every cylinder except the suspect cylinder.
That cylinder showed no movement on the meter. At this point I see no other culprit but the ECM. If anyone out there has another suspicion, I would like to hear from you. Thanks. Tobyjay
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Sunday, March 6th, 2011 AT 6:50 PM
Tiny
RASMATAZ
  • MEMBER
Disconnect the computer and check the wire for open -if okay think! Computer-
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Sunday, March 6th, 2011 AT 8:35 PM
Tiny
SATURNTECH9
  • EXPERT
The best way to test it is to get a bulb test light ground the lead end and and use the tip to see if you have power to one side of the none working injector key in the run position. Then hook the lead end to the power side of the battery and use the tip side to see if you have a ground pulse to the other side of the injector while cranking it or the engine running. After seeing what side of the circuit is missing then we can go from there. If your getting power we would have to trace the wire down. If we have no ground pulse then we have a open in the circuit loose terminal tightness or a bad ecm. But we have to rule out the other two before replacing a ecm. Let me know what you find. Also what cylinder is the none working injector on?
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Sunday, March 6th, 2011 AT 8:49 PM
Tiny
TOBYJAY
  • MEMBER
To razmataz and saturntech9 - I did what each of you suggested and located each of the injector wires through color code where they appeared on a plug at the ECM. A continuity check from the injector plug showed each wire to be good. Guess the only thing left is to replace the ECM. If you guys agree, let me know - and thanks for all the suggestions - you've both been a big help!
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Sunday, March 6th, 2011 AT 11:14 PM
Tiny
SATURNTECH9
  • EXPERT
The question's I have for you before you go changing the ecm is did you check to see if you were getting battery voltage to the other wire to the injector that doesn't go to the ecm with the key in the run position?Also did you check for a flashing ground with a bulb test light on the wire going back to the ecm when cranking the car or it running?I just want to make sure all the base's are covered.
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Monday, March 7th, 2011 AT 2:34 AM
Tiny
TOBYJAY
  • MEMBER
To saturntech9 - both wires on the injector go back to the ECM.
I am getting battery voltage measured across the two pins of the injector with the key in the run position. I checked for a flashing ground with an analog voltmeter while cranking the car. The voltmeter had no movement at all at the suspect cylinder, but did jump rapidly back and forth when the same check was done on other injectors. What do you think?
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Monday, March 7th, 2011 AT 1:20 PM
Tiny
SATURNTECH9
  • EXPERT
I have never tried to check for injector pulse with a meter I always use a noid light or better yet a test light so you can check the power and the ground pulse seperate. Only one wire at each connector goes back to the ecm that"s the ground control. The other wire goes to the fuse box.I posted a wire diagram showing each wire to the injector's let me know if the wire color's match up. Also that inop injector shouldn't read 12 volt's across it. As you can see in the wire diagram the ground control side going back to the ecm that ground is normally open. Meaning unless the ecm is sending out a pulse ground signal there shouldn't be a constant ground to that wire. Otherwise that injector would just stay open. Try this check that wire to the inop injector that doesn't have power which would be the none pink from what I see in the diagram. Put your meter on low scale ohm's ground the black lead. Now touch the red lead to that non power wire to the inop injector. Does the meter show a ohm's reading?If so unplug the connectors to the ecm and check it again. Is the ground gone now?If you still have a ground to that injector wire then you have a pinched wire shorted to ground some where. Make sure when you unplug the ecm the ignition key is off. Let me know what you find.
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Monday, March 7th, 2011 AT 5:42 PM
Tiny
TOBYJAY
  • MEMBER
Is it possible that on different cars the pink wire you show going to the fuse might be getting the plus side voltage through a connection at the ECM? I ask this because I definitely found continuity with the key off from the pink wire at the injector and what I believe to be the same pink wire at a plug on the ECM.
I understand the wiring diagram you sent, however, I do get 12V. Across the two injector terminals with the key on - and this is for all the injectors. As far as pulse coming from the ECM grounding and ungrounding one conductor - my voltmeter showed pulsations between battery plus and injector black/white with the engine running. These pulsations showed only on the working injectors and not the silent one. What makes this even more puzzling is that this morning I started the car and knew immediately that all 6 cylinders were firing. It has been intermittant before but it's been quite a while. Maybe it's nothing more than a less than solid connection at one of the ECM plugs? I have to take a 1400 mile trip with this vehicle in three weeks so I really want to solve this.
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Monday, March 7th, 2011 AT 7:47 PM
Tiny
SATURNTECH9
  • EXPERT
The power to be sent from the ecm to the injector's I really don't see that happening ecm's control ground usually if they ran too much power thru them like for those injector's then the ecm would overheat and burn up pretty fast I would think. Try pulling that fuse in the wire diagram I posted see if the power to the injector's goes away?That would tell you right there. It sound's like a bad connection issue at the ecm if everything is firing now.I would let it idle and move the wire's around light tugging etc and see if the engine start's missing. Let me know what you find.
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Monday, March 7th, 2011 AT 9:05 PM
Tiny
TOBYJAY
  • MEMBER
To Saturntech9 : Took me a few days to get a new ECM and try it out. Moved the prom from the old ECM to the new one.
The news is that it appears to have solved my problem. All injectors
are firing and the car runs normally with full power again. Removed a cable from the battery while making the change. Now I have a check engine light showing on the dash continuously. I'm assuming this is related to the ECM switch. Is there some simple way to make this indicator go off? Is it possible it's showing up because of the previous malfunction?
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Wednesday, March 16th, 2011 AT 9:07 PM
Tiny
SATURNTECH9
  • EXPERT
Let's do this see if you have a 12 pin diagnostic link connector like I posted also see if there is a terminal in the B cavity if there is follow the instruction's I posted on how to retrive the code's. Don't worry that it says it's for a saturn if you have that connector it will work the same. The saturn instruction's were better to post for you to use. Let me know what you find.
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Wednesday, March 16th, 2011 AT 9:44 PM
Tiny
TOBYJAY
  • MEMBER
Sorry, but I'm afraid I don't have a diagnostic link connector or any other device capable of reading codes. I'm told that Autozone will read codes for a customer free of charge. Should I go that route? Do you agree that this is most likely a matter of some sort of reset considering the car runs normally now?
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Wednesday, March 16th, 2011 AT 10:53 PM
Tiny
SATURNTECH9
  • EXPERT
There should be connector on the driver's side lower dash area where you would hook a scan tool too. If it looks like the one I posted then more then likely auto zone will tell you they can't read the code's for you. You will have to flash them out like I posted instruction's on how to do it. Go ahead and take it over to auto zone and see if they can do it if they can't then follow the instruction's I posted. It could be a matter of just resetting the code's we won't know till we see what code's we have. Let me know what code's we have.
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Wednesday, March 16th, 2011 AT 11:01 PM

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