1996 3800 series II, elusive Vaccuum leak - 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 04-24-2011, 09:50 PM   #21
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Did you make sure you have a O ring on the PCV valve?
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Old 04-24-2011, 10:36 PM   #22
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Quote:
Originally Posted by Danthurs View Post
Did you make sure you have a O ring on the PCV valve?
Yes, absolutely. The small o-ring on the valve and the larger one on the housing. Both are there and in place, as well as the spring. Is the pcv valve supposed to flow in both directions?

Would like to know more about that passageway that leads right into the crakncase. That almost seams like a bypass of sorts, but maybe not as it'* right in front of the throttle plate and not subjected to vacuum.
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Old 04-24-2011, 10:41 PM   #23
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It'* a one way valve, out of the crank case.

The port is in vacuum when the throttle plate is open. When plate is closed then positive pressure in the crank case would push gases threw.
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Old 05-01-2011, 11:43 PM   #24
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Default Update Found the problem.

It was the front O2 sensor. Wish I would have replaced that sensor first. At least I got an education.

The last trip I took I got 2 codes, even though it was running better, both for the Bank 1 o2 sensor. Fuel trim numbers are now good except for the rear which is still 99%. Not sure where to go with that but the cat may be worn out. As long as it'* running well and my gas mileage is back I'll be satisfied. It'* running like it was prior to the intake job and the exhaust no longer stinks.

Never realised how important an O2 sensor really is. I will keep an eye out for high percentage fuel trim numbers in the future. Unbelievable how one sensor can make or brake the driveabilty of a vehicle.
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Old 05-01-2011, 11:50 PM   #25
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The front O2 sensor tells the PCM what'* coming out. If that data is wrong the PCM will adjust. As they get old they clog up and then run richer and richer. Over time this kills the cat, and this is what the rear O2 is telling you.
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Old 05-15-2011, 09:42 AM   #26
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I had a crack in my tube on a 1995 Bonneville which I sealed, but do you know if there is a washer like seal that fits on the ends of the tube when inserting it, because I found what looked like a dried up old hard plastic washer on the one end when I removed it.
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Old 05-15-2011, 10:47 AM   #27
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I have never seen a seal there other then the tube.
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Old 05-15-2011, 11:25 AM   #28
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It looked like a very thin hose washer, but was very hard and brittle. I did check the tube afterward by spraying carb cleaner on it and there was no difference in engine speed.
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Old 05-15-2011, 11:36 AM   #29
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The EGR tube is one area that spraying does not work very well. You need to remove the tube and hld it up to the light.
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Old 05-15-2011, 12:33 PM   #30
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Ok, I will remove the tube again and check it. It did have a split in it which I repaired with epoxy but it could still be leaking. Thanks
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