96SE - PCM or Injector issue - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-17-2006, 10:00 AM   #21
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The voltage drop out..the ding ding ding.. this is sounding recently familiar to me.

Check the routing of your plug wires and if one may have a black or brown mark from being rubbed by an manifold etc. Ensure no wires are touching the O2 sensor wires on the back exhaust manifold.
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Old 05-17-2006, 10:38 AM   #22
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Lash,

I have done that...last night. I pulled all coilpacks and the ecm module off the plate. Ya 5.5 mill on the bolts...got lucky on that one.....had the socket. I cleaned up the plate, checked all the little connectors on the ecm, looked for any signs of cracks etc. So I think I have completed those first set of steps that Boost and you gave me. thanks again. I can't belleive I was actually on my toes and marked the ignition wires so I wouldn't get them crossed. I just got to work and she ran great all the way in today. Idled perfectly. Thanks for the further instructions. I will need more detail on how to do these other checks that you guys just gave me. I can tell you that the O2 sensor has not been replaced.....and I was thinking about this all last night while I was wrenching on Bufford. I will check the wires tonight and I think I'm going to go ahead and order an O2 sensor and get that on the way. might as well replace that. Questions:

1. I know what a TPS is but how do I check it ? what do you mean ?
2. checking the related wiring..I assume your talking about making sure it doesn't have a bare spot or some other problem right ? check connections etc right ?
3. Maf sensor in located on the air intake plenum right ? I think I can handle that one.
4. EGR Pintle ? Lost me on that one. I know what an EGR vavle is but the pintle....scratching head on that one.
5. Fuel pressure....I'll have to find a gage for that one. I noticed a vavle (schrader ?) on the fuel rail...is that where I hook the gage up to.....or is that for fuel pressure relief ?

Ok...thanks again guys for all your help. I will work on it again tonight and report back in. I was looking at some other post'* about scanning. I assume Willwren wants to see history on codes.....does this explain why he wants the scantool on it even though there'* no check engine light ?
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Old 05-17-2006, 11:59 AM   #23
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Quote:
Originally Posted by BMWhound
I will need more detail on how to do these other checks that you guys just gave me. I can tell you that the O2 sensor has not been replaced.....and I was thinking about this all last night while I was wrenching on Bufford. I will check the wires tonight and I think I'm going to go ahead and order an O2 sensor and get that on the way. might as well replace that. Questions:

1. I know what a TPS is but how do I check it ? what do you mean ?
2. checking the related wiring..I assume your talking about making sure it doesn't have a bare spot or some other problem right ? check connections etc right ?
3. Maf sensor in located on the air intake plenum right ? I think I can handle that one.
4. EGR Pintle ? Lost me on that one. I know what an EGR vavle is but the pintle....scratching head on that one.
5. Fuel pressure....I'll have to find a gage for that one. I noticed a vavle (schrader ?) on the fuel rail...is that where I hook the gage up to.....or is that for fuel pressure relief ?

Ok...thanks again guys for all your help. I will work on it again tonight and report back in. I was looking at some other post'* about scanning. I assume Willwren wants to see history on codes.....does this explain why he wants the scantool on it even though there'* no check engine light ?
Make sure you don't get a Bosch O2 sensor, they dont' work well in our Bonnevilles. Get an AC Delco if possible.

1. TPS - The best way to check it is with a scanner (there it is again, lol), but you can check voltage with a voltmeter. I haven't done it and have been having trouble finding the values and method for you, so I'll have to get back with you on that one. I can tell you that if you hook up a voltmeter, you should get a smooth increase in voltage throughout the acceleration curve. I'll get back with you when I find better info.
2. Correct.
3. MAF sensor is located on your throttle body. See this TECHNFO article for cleaning. http://www.bonnevilleclub.com/forum/...e=article&k=64
4. The pintle is the little piece in the EGR valve which position is measured for input.
5. Yes, use the schrader valve.

And yes, a good scan tool will provide much more info than just a simple code. Remember that there are things that go on before a code is set that tell you much more about an issue.
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Old 05-17-2006, 12:16 PM   #24
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Lash,

Thanks for the reply. Ya, I plan on GM parts direct for that O2 purchase. I'm hearing a common theme here about the scanning tool. When I was at Autozone they are using the Actron CP9145 Super AutoScanner. Can this unit retreive the info that we need to make a better diagnosis ? Troubleshoot the TPS, etc ? The fella mentioned to me that I could "borrow it". That might help me save some bucks.....I don't have the 280.00 spare right now. If that tool will work I'll check into borrowing it to help us out. Otherwise 1993 SLE mentioned that there might be a local Illinois member that could help, Anyone close to Champaign Urbana that would be willing to help ?
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Old 05-17-2006, 01:48 PM   #25
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BMW...the 9145 should be the model that shows live data. That would give you TPS and other readings. Borrowing is always better than buying when you don't have a continual need
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Old 05-17-2006, 01:56 PM   #26
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Thanks Boost. I'll see about borrowing it. Is It user friendly - Like Windows XP Just kidding. I just want to make sure I give you fellas all the info that you need to help me diagnose Bufford. When I do get a hold of the scanner, what should I do to collect this live data ? hook it up and just run around with it while I drive ? Please advise. Thanks P.* I did read through Amazon (they sell it for 279.00) that it will read live data. Will the booklet that comes with it tell you how to look at certain sensors ?
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Old 05-17-2006, 02:15 PM   #27
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It'* intuitive. You won't have any problems.
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Old 05-17-2006, 11:16 PM   #28
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Hello again,

Well, I have pulled the O2 sensor, and it looked fine. no white residue. Also pulled the EGR and I didn't see anything alarming. I did not see this Pintle...because I don't know what it looks like or what I'm looking for. From what I recall if the EGR is really clogged up with carbon then you want to replace it. I did not see any real buildup of carbon. I also noticed a clicking sound when I moved the EGR around. So whatever is inside it, is moving around - I don't know if that helps. I also pulled the MAF and it looked fine as well. I did not see any dirt or anything built up on it. Now the bad news..... I can't check the rest of this stuff because I don't have the scantool or fuel pressure gauge. I know I can by the fuel pressure gauge for 37.00 + tax at autozone, but I can't bring myself to buy it to only use it once. The scanner that Autozone uses is not the model that I posted on earlier. It looks just like it but it only pulls codes. I also went to Advanced Auto to see if I could be loaned these 2 tools but they don't either. I did look at all the connectors on the TB and pulled connectors, inspected, and reseated. All looked great.

I inspected the ignition wires, and all those looked fine as well. I did notice one thing though. The plug wire for the cylinder that is firewall - driver side (directly below the EGR valve) was drooping and touching the O2 sensor (sorry I tried looking up what cylinder number it was but I didn't have any luck). I noticed all the firewall side plug wires had the black plastic cover on them. That particular wire black plastic cover for that cylinder was brittle from the heat of the rear exhaust manifold I would guess, but it
was partially (1/2 of it) coming off the plug wire, and that was the part that was touching the 02 sensor. In other words the part of the plug wire that didn't have any plastic cover on it was the part touching the sensor. Could that be the problem ? who knows. I put a tie wrap around the plug wire and kinda suspended it from the little connector holder that holds up the 02 sensor connector. The plug wire is far away from the 02 sensor now. The wire did not show any signs of melting or discoloration.
The car ran pefectly today, and no check engine lights or codes Again is there anyone out there that can help me with a scanner or fuel pressure gauge ? Your help would be greatly appreciated. Thanks again guys...I'm a little discouraged now, because the car has decided to not mess up (for the moment) and I can't finish the testing because of a lack of tools :( Don't know what else to do. I'm going to take another trip 700 miles this saturday......I guess we'll see what it does then.
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Old 05-18-2006, 08:20 AM   #29
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Well, there may be good news in all this for you, as there certainly seems to be a corrolation between plug wires touching O2 sensor wires and mis-fires, from what we are seeing. That MAY literally have been your main problem. Let'* hope it was.

On another note, I thought I should clarify on that EGR pintle. The thing that shakes around in there when it'* clear and working correctly, IS the pintle. Sorry about not being clearer before.

Anyway, I certainly hope that you have resolved your issue. Let us know if it happens again or even if it has been resolved for sure.

EDIT: Some theory behind the plug wire touching the O2 wire and it'* connection to a mis-fire, from what I know. The O2 is a very low voltage sensor and sends voltage signals back to the PCM so that the PCM can make corrections to the fuel trim if necessary. The strong electromagnetic field from a plug wire can change the signal from the O2 enough so that the PCM thinks it is getting a rich signal and it will lean out the A/F ratio. This can cause stumbling, mis-fires, and even stalling.
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Old 05-18-2006, 09:23 AM   #30
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Side note....The cylinder is number 6. That plastic wire loom you found on the wires is good, however that #6 wire should not have it on over the exhaust manifold. It would simply melt off (voice of experience talking )

Sounds like you are on the right track for finding the issue. That wire could have caused issues.
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