1989 olds 88 injector not firing or erratic 3.8

1989 OLDSMOBILE 88
75,000 MILES
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DAVIDJ7479
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Originally my car would not start, replaced the ICM, it then started but ran rough, so I replaced the coil pack, wires and plugs. Still running rough, especially when accelerating around 40 mph.

Took it to a shop and they said that #5 injector was not firing, not sure why. So I replaced the injector. When it starts cold it works, within 5 minutes it stops. Now I don't think it it firing at all.

I saw on another post about checking for 12v and pulse. With key on I have 12 volts on one side of the connector, also when running. When I hook up a test light to the positive on the battery the pulse side glows, then cuts off. When running it will be off and then glow for about 4 seconds, then turn off, maybe 15 seconds later it will start to glow, then turn off.

I checked another cylinder and saw a rapid pulse like when a plug would fire.

Does this mean bad ECM? I wouldn't think a bad wire would do that.

Your thoughts?


Thanks
Sep 9, 2013 at 3:36 PM
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JACOBANDNICKOLAS
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To be honest, I don't think a bad wire would do it either. However, I would check it to make sure. Does it ever pulse?
Sep 9, 2013 at 3:40 PM
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DAVIDJ7479
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When I checked out for 6 minutes or so off And on it did not fire. I will let it cool off and try again leaving it on to see if it fires

How would I go about checking the wire.
Sep 9, 2013 at 3:53 PM
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DAVIDJ7479
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Just checked again for pulse. Did pretty much the same, light would come on for about 2 seconds then go off, about 30 seconds later the light would come on for a second or two. One time it was like a quick pulse, but nothing after that.

If I take the probe off of the connector, every time that I touch the connector the light comes on bright for a second or two, sort of like it is discharging or something?
Sep 9, 2013 at 4:32 PM
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JACOBANDNICKOLAS
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That is interesting... I wonder if the wire is bad. Can you check it for continuity?
Sep 9, 2013 at 6:05 PM
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DAVIDJ7479
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.Thanks jacobandnickolas for the response.

I checked with continuity tester. There was a steady beep. Checked resistance and it was 31 ohms. your thoughts?
Sep 10, 2013 at 4:53 PM
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JACOBANDNICKOLAS
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The resistance sounds high. Can you compare it to another wire to a different (working) injector?
Sep 10, 2013 at 5:36 PM
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DAVIDJ7479
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I can . Will be tomorrow. Will it tell me anything if I ran the car, used a light probe connected to the battery and poked the suspect wire at the ecm to see if I get the ground pulse? If it is a bad wire I should still get the pulse at the ecm?
Sep 10, 2013 at 5:45 PM
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JACOBANDNICKOLAS
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That is a good idea. And yes, if the wire is bad, the light should pulse if you are getting the signal right from the ECM.
Sep 10, 2013 at 5:48 PM
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DAVIDJ7479
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ok, checked resistance on other wires, is was about .5 ohms. so I took some speaker wire, spliced the wire at the ECM and ran it to the injector, now I have a pulse. :)

But, it runs like crap, when accelerating around 45, real bad vibration.(pretty much the same as before)

A couple of things that I noticed, the negative pulse wires have about 500k resistance between them, also to ground. Should they be open when the car is off? Also when I was checking continutiy between the suspect wire, it shows continuity to the other neg pulse wires?
Sep 11, 2013 at 12:09 PM
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DAVIDJ7479
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Also, very erratic idle. Checked codes on computer, none, just 12.
Sep 11, 2013 at 12:44 PM
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DAVIDJ7479
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I drove it At lunch time. It had bad idle. Shake bad on acceleration. When i got home, tried to start it. It will not run. With gas pedal pushed it eill run a little but rough, backfires then dies
Sep 11, 2013 at 3:35 PM
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DAVIDJ7479
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ok, I disconnected the Mass Air Flow Sensor, and it will start and run, a little rough though. It drives better, no major jerking around 45 mph. So confused.
Sep 11, 2013 at 4:52 PM
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JACOBANDNICKOLAS
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Did you clean the MAF sensor or replace it?
Sep 11, 2013 at 6:44 PM
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JACOBANDNICKOLAS
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If you have a pulse to all injectors, that is great. I thought the resistance in the suspected wire was high. Now, I need you to pull the plug out from the cylinder that had the injector problem and check to see if it is still good. If the injector was injecting fuel all the time, it may have fouled the plug.

Let me know what you find. And sorry this is taking so long. It requires many steps to locate the source of the problem sometimes. We'll keep trying.
Sep 11, 2013 at 6:48 PM
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DAVIDJ7479
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I did not touch the MAF sensor, the closest I came to it was replacing the air filter.

I will change the plug and clean the MAF sensor with the appropriate cleaner.

It's ok it is taking a while, it's my daughter's car, she has my truck.
Sep 12, 2013 at 6:10 AM
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DAVIDJ7479
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I replaced the plug and cleaned the MAF sensor with MAF sensor cleaner. No change.

Engine sounded really bad, loud. Chased down a vacuum leak at the PCV valve. (I had the shop change it out when they were troubleshooting and found the injector not firing. I guess the hose has rotted, when I removed the PCV valve, which I could barely get to, part of the hose came off with it. I suppose this is where the vacuum leak was coming from.

Before I pulled the PCV valve, I just held it down, most of the leak went away, still ran bad.

Now, I can't see where the PCV hose goes to? Surely I don't have to pull the plenum/intake?

Sep 12, 2013 at 11:26 AM
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DAVIDJ7479
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ok, replaced the pcv hose, found another leak at the canister, now it runs with the MAF sensor connected. :)

It's running much better. It idles a little rough in gear. When accelerating I get a vibration, especially above 40 mph, let off the gas, it stops vibrating.
Sep 13, 2013 at 4:06 PM
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JACOBANDNICKOLAS
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We need to get your truck back. lol My son has mine right now which leaves me stuck at home.

Is the car running in an acceptable manner?
Sep 13, 2013 at 6:02 PM
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DAVIDJ7479
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Well, I'd like to get it without the vibration on acceleration. :) almost feels like cv joint. But, 2 weeks ago it did not vibrate when cold?
Sep 13, 2013 at 6:41 PM
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JACOBANDNICKOLAS
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You mean it feels like something other than the engine causing the vibration?
Sep 13, 2013 at 6:54 PM
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DAVIDJ7479
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Yes. But when I took it to the shop, that's when they found the injector not firing. . Once when I drove it cold. It ran smooth even on acceleration. I would think cv would be consistent. I don't notice rough on turning corners.

Sep 13, 2013 at 7:02 PM
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JACOBANDNICKOLAS
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Was the injector replaced?
Sep 13, 2013 at 7:11 PM
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DAVIDJ7479
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Yes
Sep 13, 2013 at 7:13 PM
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DAVIDJ7479
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Yes, I did the injector
Sep 13, 2013 at 7:14 PM
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JACOBANDNICKOLAS
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And there was no change? If not, is that injector getting power?
Sep 14, 2013 at 5:32 PM
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DAVIDJ7479
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I will need to double check that. It felt like the right side. I was going to rotate the tires to see if it makes a difference m when I Took the front tire of I noticed it had a low profile. 60 series the rest are 70. Put it on the back and made a bbig difference. Going to deal the one out.
Sep 14, 2013 at 5:40 PM
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JACOBANDNICKOLAS
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Let me know what you find. And yes, that tire needs to go. Keep them all the same size. If, however, there is no change, check the injector to make sure it is getting power. If it is, remove the plug to see if it is wet. Also, check compression in that cylinder.
Sep 14, 2013 at 5:52 PM
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DAVIDJ7479
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The shop checked the compression when they were troubleshooting, said it was good.

I decided to drive it to work to check on a replacement tire. It ran like crap.horrible vibration on acceleration especially above 40 mph. Decided to skip the tire for now.

Went home at lunch time to check the plugs, no way all could be firing. All were dry, but the plug on #4 (different than #3 I had been working on) did not have a nice clean white insulator like the other plugs, tan color.

So I checked for pule on that cylinder.....nothing. I used a probe to stick it, so I disconnected it to make sure I was getting through the wire and no pulse. I noticed when i started the car without the injector connected, no real difference in the way it was running.

So when I get home today, I will trace that wire back and check resistance.

Sep 17, 2013 at 12:53 PM
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DAVIDJ7479
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ok, let's back up. After further investigation, it looks like I cut the wrong wire at the computer. The ground pulse wire at the injector is black/pinkish. On the schematic it says that #3 cylinder is black/light blue. I cut the black/red which is #4 and why it is not firing.

When I went back and probed the original injector that is not firing, I get .6 ohms to the black/light blue wire, I don't know why it is black/pink up on top. Checked for pulse on the original wire at the computer, same thing quick pulse, nothing for 20 seconds then glows for 2 seconds.

So I'm back to my original problem. I check the resistance from the bad injector wire to ground, get about 80K. Checked the other injector, infinity.

So I removed the plug to the computer, rechecked to ground, infinity. Which says inside the computer to ground is about 80k??????
Sep 17, 2013 at 4:32 PM
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DAVIDJ7479
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Wish we still had a carburetor and points to file if needed.
Sep 17, 2013 at 5:18 PM
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JACOBANDNICKOLAS
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Dave:
Let me make sure I understand. By mistake, you cut the wrong wire. However, you were then getting a pulse to the original bad injector. Now, you repaired the mistake and you are back to square one. Is that correct? If it is, it sounds like the PCM is bad if you are not getting a pulse there.
Sep 17, 2013 at 5:50 PM
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DAVIDJ7479
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That is correct. Now the original injector is back where it was. I am getting continuity back to the computer, must have checked the wrong wire originally. I agree, don't know what else it could be, the original injector is not getting a pulse and the wire seems good.

I'll have another PCM tomorrow. After I re-solder my mess, I will put it on and see how it goes.

Sep 17, 2013 at 6:21 PM
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DAVIDJ7479
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That did it. :)

Runs like a champ.

When I took the old one out I noticed that it was a re-manufactured ECM.

Anyway, it is done, thanks so much for your help, saved me a bunch.
Sep 18, 2013 at 4:09 PM
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JACOBANDNICKOLAS
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Dave:

I'm so glad you got it fixed. Was the PCM expensive?
Sep 18, 2013 at 6:12 PM
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DAVIDJ7479
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Not bad, got it for $85, with core. I took out my EEPROM, swapped it out. Unreal how much better it drives. I really have never drove it until it's broke. That's the only time that my daughter brings that car around, when it is broke. :(

I really appreciate your help on this.

How can I make a contribution?
Sep 18, 2013 at 6:21 PM
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JACOBANDNICKOLAS
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Dave:
I'm just glad I was able to help. You can donate the next time. At least I hope you come back.

Joe
Sep 18, 2013 at 7:38 PM