Down on power! Why?
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,695
Likes: 0
From: Chicago Illinois
Down on power! Why?
My 93 LT1 is all of sudden running like crap. (Mods in profile)57,000 miles. opti, plugs wires and O2 sensors are 1 year old. It idles fine, on acceleration feels like its fludderring. A slight shake to the car now and some backfiring on decleration. Car feels like it has half the power it once had. Tail pipes are black! I looked for anything obvious, loose connection, even changed what looked like a cooked O2 cause the plastic holder was melted away. Afriend told me possibly check fuel pressure or even the coil. Most likely it wont be me fixing this thing, but I wouldnt want to get screwed around by a shop. What are your thoughts?
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Hard to say. I think your friend is right. Could be fuel or fire. Check electrical system out. Could be wires coil etc. Also check fuel pressure and go from there.
Melting Slicks
Joined: Feb 2006
Posts: 2,240
Likes: 0
From: Cleveland OHIO
Process of elimination, I would first check for codes, check the fuel pressure, check the f.p.r. but if I were guessing which I am I would look to the coil. You know how to check the fuel pressure and the regulator right ? Do you have a stock coil or are you running a msd coil ?
Last edited by wayne lowry; Jul 20, 2007 at 01:09 PM.
Racer
Joined: Dec 2004
Posts: 470
Likes: 0
From: Phoenix Arizona
Check/ test your injectors. 
Did you use any over the counter octain boost, as that will cook your 02 sensor. Also I agree with other posts fuel pressure also could cause rich / black exhaust tips.
Did you use any over the counter octain boost, as that will cook your 02 sensor. Also I agree with other posts fuel pressure also could cause rich / black exhaust tips.
Last edited by jghmczo6; Jul 20, 2007 at 02:04 PM. Reason: added info
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Process of elimination, I would first check for codes, check the fuel pressure, check the f.p.r. but if I were guessing which I am I would look to the coil. You know how to check the fuel pressure and the regulator right ? Do you have a stock coil or are you running a msd coil ?
Otherwise, it could be just about anything.......really
You could have easily lost an O2 sensor(s), even if it is only a year old...
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Race Director
Joined: Jan 2005
Posts: 10,641
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From: Slidell Louisiana
Or you can pull out your trusty paper clip
http://www.corvettebuyers.com/c4vettes/codes.htm
Last edited by aboatguy; Jul 20, 2007 at 06:53 PM.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,695
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From: Chicago Illinois
My big shot buddy, Dom Sorresse who recently moved up to the ZR1 section is going to see if we can find the problem on his scanner. I should know more by Sat afternoon.
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
A bad O2 sensor will not necessarily throw a code. The scanner should show you if it's working properly or not. Even if it's bad (from my personal experience), it shouldn't run bad, just rich and smelly.
Are you running without cats? Sometimes that can cause the backfiring.
Are you running without cats? Sometimes that can cause the backfiring.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,695
Likes: 0
From: Chicago Illinois
I have no cats but all these symtems came at once. Im just wondering if it could be fuel filter. The last time the car was running good I was down to my last bar on gas gage. Would clogged fuel filter cause these symtems.
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
I have a '93 also and today was the first time that I ever got down to one bar. I was scared that I might suck up some of the crap in the bottom of the tank. I think that changing the fuel filter would be a good idea. Even if it's not the problem, it's a cheap and semi-easy project. I would try that first.
Drifting
Joined: May 2005
Posts: 1,370
Likes: 1
From: Raleigh NC
Change the coil and fuel filter...cheap and at least that will rule out some potential problem areas. Does your year have a MAF? If so, and if you have a K&N, oil from the filter can get on the MAF wires causing it to run poorly. Check that and clean it with electrical cleaner.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,695
Likes: 0
From: Chicago Illinois
Change the coil and fuel filter...cheap and at least that will rule out some potential problem areas. Does your year have a MAF? If so, and if you have a K&N, oil from the filter can get on the MAF wires causing it to run poorly. Check that and clean it with electrical cleaner.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,695
Likes: 0
From: Chicago Illinois
Alright, fuel pressures at 40 and goes up on road test to 42 and some times goes down to 38. Consistantly at 40 though. What should the pressure be at? How do I check regulator and where is coil located ,whats it look like?
Race Director
Joined: Jan 2002
Posts: 12,263
Likes: 86
From: O'Fallon Missouri
Pull the fuel pressure regulator's vacuume line and check for fuel, if fuel is present it's bad.
The coil is located at the front of the passenger's cylinder head. Will have a coil wire (looks like a spark plug wire) attatched.
The coil is located at the front of the passenger's cylinder head. Will have a coil wire (looks like a spark plug wire) attatched.
Racer
Joined: Oct 2003
Posts: 491
Likes: 1
From: Owasso OK
check your spark plug wires carefully....I had a similar problem not too long ago, long story short, it ended up being my #6 cylinder spark plug wire was grounded to the exhaust manifold.....just my two cents.