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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 05-23-2004, 03:26 AM   #1
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Default Spark plug color

I had Autolite AP605 spark plugs in my 95 SSEi for over 3000 miles, and they still look bright white. My gas mileage has been in the 13 MPG'* for some time, but otherwise the engine runs good. What could be causing them to run so hot? It would seem I was running too lean, but the gas mileage doesn't seem to show this. Would a leaky PCV valve cause this? I also recently replaced the plug wires and O2 sensor AC-Delco and a K/N dropin filter, with the original air box input tube replaced with a larger tube.
My car has 57K original miles on it. I also checked 0 to 60 and get between 8 to 9 seconds, which I believe is about right for a stock car of that year.

I'm also thinking maybe the oxegenated California gas is causing it to burn lean. Any other california owners have a similar experience?
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Old 05-23-2004, 09:51 PM   #2
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Possibility of a vacuum leak? Check all the lines, but the best way of determining if you are indeed running lean is by looking at the 02 sensor output through a diagnostic scanner.
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Old 05-24-2004, 12:51 PM   #3
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I don't have direct access to a scanner, other than pay someone. This has the oddball 95 hybrid. I may be forced to though, but I did just replace the O2 sensor. Also, my vacuum at idle is about -10 on the boost guage, and maybe around -8 when I turn on the AC, also at idle. Does that sound about right? The car runs great otherwise, no knocks, and never has knocked since I bought it 9 years ago. The only concern is gas mileage and plug color seems odd. I also tried some AC-Delco 41-601 plugs (OEM) and after 300 mile trip, still white like new appearance. Could plug wires cause a problem? I don't remember the brand, but they were about $50 at Kragen, which I put in last year. They have a lower resistance than OEM which would allow a hotter spark.

Does anyone have a recommendation on where I can get a scanner, and what model number. I think I also need a special cable.
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Old 05-24-2004, 03:04 PM   #4
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Hm, seems to be running lean consistantly and no SES light shows up... Maybe the MAF was already bad, and your new O2 was faulty, so the PCM doesn't know it'* lean. That'* just a guess. Is the IAT securely plugged in to the airbox?
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Old 05-24-2004, 04:11 PM   #5
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Yes. IAT is there. I tested it awhile back and it looked okay. Chiltons has a method of testing the MAF. I'll look into that some more. Still, why would a lean condition cause it to use more gas?

As far as the scan tool, it is OBD1 with an OBD2 connector. Is it possible to buy a cheap OBD1 scantool, and construct an adapter that allows it to work with an OBD2 connector, or is it more complicated than that?
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Old 05-24-2004, 09:22 PM   #6
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Being lean, you would need to open the throttle more to get enough power to move. The engine will unnecessarily compress too much air and get nothing out of it. It'* called pumping losses.
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Old 05-27-2004, 06:06 AM   #7
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Default Same problem

I have the same car, '95 SC, with the same problem. I started get around 13-15 MPG and changed plugs, wires, air cleaner, O2 using acdelco, cat, and still no luck. My plugs are white and I happend to notice that if I got on it really hard and got out quick to check the manifolds they were bright orange. I stoppped driving it till I figure it out. Anyone got ideas, MAF, IAT, TPS...

Also I'd like to find a way to scan mine also with out spending $$$. Damn '95GM'*.

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Old 05-27-2004, 02:45 PM   #8
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That'* interesting that you mention the glowing manifold. I just did that last night and had them glowing too, but I read on another thread that a little glowing after a hard run is normal. Can anyone else try this, who'* car is running normal to see if this is common. I would expect it to happen more on SC cars since it will run harder under heavy acceleration.


Read the second reply in this:
http://www.bonnevilleclub.com/forum/...owing+manifold

I did have another thought on this though. If the EGR wasn't opening up, it might cause it to run too hot. Just another thing to check. I don't get any check engine light either.
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Old 06-09-2004, 07:25 AM   #9
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Default glowing exhaust

Will I know my problem is not clogged exhaust because I can disconnect it after the O2 sensor and it will still glow. I was kinda thinking about the EGR also but I'm not sure how to check it yet. Also, since mine does not have a MAP sensor I thought maybe the MAF sensor was bad but havent been willing to hand out the $ to get a new one yet.

Does anyone know what the symptoms of a bad injector are. Or what the proper PSI on a '95 Supercharged is by chance. Just grasping at straws here.

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Old 06-09-2004, 07:29 AM   #10
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Default glowing exhaust

Will I know my problem is not clogged exhaust because I can disconnect it after the O2 sensor and it will still glow. I was kinda thinking about the EGR also but I'm not sure how to check it yet. Also, since mine does not have a MAP sensor I thought maybe the MAF sensor was bad but havent been willing to hand out the $ to get a new one yet.

Does anyone know what the symptoms of a bad injector are. Or what the proper PSI on a '95 Supercharged is by chance. Just grasping at straws here.

Thanks
ctj
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