Diagnosis help....
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 9,740
Likes: 0
From: A Pretty Part of MO
Diagnosis help....
Hey all!
I need some of your expertise...
I have a 1990 coupe, L98 auto. It is acting up on me, and I'm buggered trying to figure it out. What it does is it will run really rough. When it acted up on me this morning, it would just hold second gear and not want to shift. When I pulled into the parking lot at work this morning, there was smoke coming out from underneath. White smoke from right around the main cat. It looked like maybe a fluid had sprayed on it. I'm thinking tranny fluid?
The engine was running really wierd. It sounded like a 2 cycle motorcycle or chainsaw. Real rough and pulsing. It would barely idle at a stop and had no power to accelerate.
If it is a tranny problem, I wouldn't think that would cause the engine to run roughly unless there is a vaccuum leak or something like that.
Oh, oddly enough, I drove it to the dealer yesterday to let them take a look at it, and in 30 miles of driving, it ran fine, had no problems. It ran fine for about 10 miles today before it acted up.
Also, my oil pressure runs at about 70 psi.
Any guesses?
TIA,
chris
[Modified by 90qzrblu, 10:11 AM 3/11/2004]
[Modified by 90qzrblu, 11:47 AM 3/11/2004]
I need some of your expertise...
I have a 1990 coupe, L98 auto. It is acting up on me, and I'm buggered trying to figure it out. What it does is it will run really rough. When it acted up on me this morning, it would just hold second gear and not want to shift. When I pulled into the parking lot at work this morning, there was smoke coming out from underneath. White smoke from right around the main cat. It looked like maybe a fluid had sprayed on it. I'm thinking tranny fluid?
The engine was running really wierd. It sounded like a 2 cycle motorcycle or chainsaw. Real rough and pulsing. It would barely idle at a stop and had no power to accelerate.
If it is a tranny problem, I wouldn't think that would cause the engine to run roughly unless there is a vaccuum leak or something like that.
Oh, oddly enough, I drove it to the dealer yesterday to let them take a look at it, and in 30 miles of driving, it ran fine, had no problems. It ran fine for about 10 miles today before it acted up.
Also, my oil pressure runs at about 70 psi.
Any guesses?
TIA,
chris
[Modified by 90qzrblu, 10:11 AM 3/11/2004]
[Modified by 90qzrblu, 11:47 AM 3/11/2004]
Cruising
Joined: Feb 2004
Posts: 12
Likes: 0
From: Winfield Il
Re: Diagnosis help.... (90qzrblu)
Could also possibly be one of three things if it is running rough.....
bad or plugged Fuel injector.
Bad or burned valve.
Flat spot on the CAM...
My '85 failed emissions and was running rough too.....the idle would pulse a little bit too. Took it into a shop and was told it was one of the three things mentioned above on Cylinder #2. Haven't had much of a chance to investigate the 3 items mentioned above as of yet.
bad or plugged Fuel injector.
Bad or burned valve.
Flat spot on the CAM...
My '85 failed emissions and was running rough too.....the idle would pulse a little bit too. Took it into a shop and was told it was one of the three things mentioned above on Cylinder #2. Haven't had much of a chance to investigate the 3 items mentioned above as of yet.
Burning Brakes
Joined: Feb 2000
Posts: 824
Likes: 2
From: Camden SC
Re: Diagnosis help.... (tiedt)
Well, I too would start with the cat, then proceed down the list. I'd jack up the car and head for the catalytic converter. Look for any signs of high heat. Check the floor area above the cat. Is the cat significantly discolored? Bump the cat with your hand, listening for a rattling sound or anything that resembles loose chunks of metal.
Sure sounds like a cat. As stated above, could be injector
Sure sounds like a cat. As stated above, could be injector
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 9,740
Likes: 0
From: A Pretty Part of MO
Re: Diagnosis help.... (greenvette95)
check your oxn senser :flag
Yeah, I did the O2 sensor a couple months ago, and it helped some. I'm leaning towards a new cat and eliminating the precats. I figure it can't hurt.
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: Diagnosis help.... (90qzrblu)
Just because the O2 sensor is new......do not think it cannot go bad! My brand new GM sensor lasted about 6 months and locked up at .19 volts. I was very low on the state emissions test and became concerned. A new sensor made the "queen" run much better! If anyone needs to pass emissions test, I have an used but not abused O2 sensor they can have! Also check those Multec injectors (should be 16 - 17 ohms resistance).
SAM
[Modified by Sam Lam, 6:40 PM 3/12/2004]
SAM
[Modified by Sam Lam, 6:40 PM 3/12/2004]
