Car running rough at idle; high carbon monoxide

Tiny
DSTRICKLER
  • MEMBER
  • OLDSMOBILE
1993 Oldsmobile Bravada, 141,000 miles, automatic, AWD. Help. Please. Car has been running rough at idle for three years. Couple years ago, EGR valve was cleaned and ran well for about 6 months. Computer was checked - OK - and prom was replaced two years ago. Very fouled spark plugs replaced three weeks ago. Last week, spider (fuel injectors, fuel pressure regulator, etc.) Was installed. Fuel filter replaced. IAC valve OK. Intake manifold appears clean. EGR was replaced 9 months ago, and again replaced last week, even though appeared OK; shop even tried bypassing the EGR by plating off, but no difference. Compression check run on engine last week also, and all appears OK. Car still runs rough at idle, and shop has no idea what's wrong.

Just had the vehicle emissions-tested last Friday. Carbon monoxide is 69; allowable 25. Not good. Any ideas?

P.S. Guys, I'm trying to make a donation, but your site won't take my credit card(s). Keeps saying I have a Paypal account, which I has set up years ago, but was never able to make work. So, I'd love to give you a donation via credit card, but looks like I need help with that, as well as with my car.
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Monday, July 30th, 2007 AT 9:43 AM

5 Replies

Tiny
JACK42
  • MEMBER
Could be ignition related. Have you replaced the plug wires? Cap and rotor? What kind of spark plugs were used? Does it have strong blue spark at the coil and the distributor?
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Tuesday, July 31st, 2007 AT 8:04 AM
Tiny
KIN CHAN
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Need the rest of the test #s. Both low & high speed. Is it on a dyno test or just 2 speed idle. Without the rest of the #s. How do I know ur fuel bal, misfire. Etc?
U seems to replaced a lot of parts and maintain ur car pretty good. So it sure be fairly straight foreward.
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Tuesday, July 31st, 2007 AT 8:40 AM
Tiny
DSTRICKLER
  • MEMBER
1993 Oldsmobile Bravada, 141,000 miles, automatic, AWD.

To Kin Chan: I'll have to get the rest of the info from the report from the Colorado Emission Test Station. Will get back to you. Thanks.

To 2CarPro Jack: Will check the plug wires. Cap and rotor were replaced about 15,000 miles ago. Sorry, don't know the kind of spark plugs the shop just put in, but I suspect they were nothing fancy, and made no difference to how the car runs. Will check spark at coil and distributor. Thanks for your thoughts.

Couple guys here at work thought the problem could be the intake air sensor (aka mass air flow sensor) and/or CO2 sensors. Could these be part of the problem? Don't think either have ever been changed out.
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Tuesday, July 31st, 2007 AT 1:36 PM
Tiny
JACK42
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The MAF could cause a lean misfire condition.
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Wednesday, August 1st, 2007 AT 7:57 AM
Tiny
DSTRICKLER
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Yea! Got the problem licked, I think. It was the throttle position sensor. Runs 99% better. Now if it will pass emissions, I'm good to go. Thanks for all your ideas.
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Wednesday, August 1st, 2007 AT 5:00 PM

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