LT1 miss problem
Instructor
Joined: May 2001
Posts: 125
Likes: 0
From: 142K 94 Torch Red Mannheim, Germany
I also have a 94 (daily driver, AT, 120K) and have had had the exact same problem as you, it's been on and off for a couple years now and has been driving me crazy.
I've changed the opti, water pump, coil, EGR, plugs, wires, air and fuel filters, traced as many vacuum lines as I could, checked all for leaks dryrot etc... I had a shop in St. Pete run the diagnosis program and everything came out fine...but..still was losing power and stuttering.
The only thing strange I have found was one of my injector wires was pretty rough and fell apart when I touched it. I had to bypass the connector on the right side under the fuel rail cover to reconnect. Run's a tad better but still stutters going from 4th to O/D occasionally.
A few weeks ago I lost all power driving home...no response to the accelerator and the RPM's slowly went down until she died at about 15 MPH. I had zero load on the engine, I guess she was tired...Pulled over and she started right back up and drove fine...weirdest thing...
I've changed the opti, water pump, coil, EGR, plugs, wires, air and fuel filters, traced as many vacuum lines as I could, checked all for leaks dryrot etc... I had a shop in St. Pete run the diagnosis program and everything came out fine...but..still was losing power and stuttering.
The only thing strange I have found was one of my injector wires was pretty rough and fell apart when I touched it. I had to bypass the connector on the right side under the fuel rail cover to reconnect. Run's a tad better but still stutters going from 4th to O/D occasionally.
A few weeks ago I lost all power driving home...no response to the accelerator and the RPM's slowly went down until she died at about 15 MPH. I had zero load on the engine, I guess she was tired...Pulled over and she started right back up and drove fine...weirdest thing...
Safety Car
Joined: Apr 2004
Posts: 4,532
Likes: 7
From: Lahaina Hi
I had the same low speed miss and at 1800 rpm's.
Replaced the 1 year old Jeg"s coil with a MSD and the module,at the same time .
Went away.
2 weeks later back again, but not exactly the same miss.
Replaced right O2 sensor with a wide band from denso.
Still the same.
Took the car over to the airport close by which is pitch black out .
Raised the hood looked at the coil.
The coil was arching on it's self, a white light.
When I reved up the car the light would go away.
I shut off the engine and put some dilectric grease between the coil and the metal square that holds the coil inplace.
The miss has not reared its ugly head now for 2 mths.
Also the exaust does not stink anymore when I first start the engine.
Replaced the 1 year old Jeg"s coil with a MSD and the module,at the same time .
Went away.
2 weeks later back again, but not exactly the same miss.
Replaced right O2 sensor with a wide band from denso.
Still the same.
Took the car over to the airport close by which is pitch black out .
Raised the hood looked at the coil.
The coil was arching on it's self, a white light.
When I reved up the car the light would go away.
I shut off the engine and put some dilectric grease between the coil and the metal square that holds the coil inplace.
The miss has not reared its ugly head now for 2 mths.
Also the exaust does not stink anymore when I first start the engine.
Team Owner
Joined: Mar 2001
Posts: 30,858
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Originally Posted by REDC4CORVETTE
Took the car over to the airport close by which is pitch black out .
Raised the hood looked at the coil.
The coil was arching on it's self, a white light.
When I reved up the car the light would go away.
I shut off the engine and put some dilectric grease between the coil and the metal square that holds the coil inplace.
The miss has not reared its ugly head now for 2 mths.
Also the exaust does not stink anymore when I first start the engine.
Raised the hood looked at the coil.
The coil was arching on it's self, a white light.
When I reved up the car the light would go away.
I shut off the engine and put some dilectric grease between the coil and the metal square that holds the coil inplace.
The miss has not reared its ugly head now for 2 mths.
Also the exaust does not stink anymore when I first start the engine.
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Originally Posted by Reddy94
I'm also trying it tonight..I hope I see something...This has been a nagging issue for years...
Thanks for the tip!
Thanks for the tip!
Also, don't mistake Corona Effect for arcing. Corona Effect often appears as a blueish colored dim flash of diffused light reflecting off the metal base (hex head area) of the spark plug, but you never see the bright point of spark flash like with an arcing event-- Corona is more of a soft dimmer flashing, but it will be in time with the plug firing.
Definition of Corona Effect:
Corona Effect : Corona Effect is a phenomenon which may be observed when viewing an engine running at night with the hood up. This phenomenon appears as a greenish blue halo around the wires. The amount of corona is dependent mainly on the humidity of the air and the amount of voltage pushing the electrons through the conductor. As the voltage and/or humidity increase, a more pronounced corona is observed. Be aware that it does not cause any problems. It is normal and there is absolutely nothing wrong with the wires. An actual arcing of a spark to ground does indicate a problem. A spark going to ground will make a noise, corona does not make noise.
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Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
Originally Posted by elefkow
I'll bet you the computer is throwing a code. You need to access it before you start replacing parts. Its a simple process that has been covered here many times.
Baloney--I've had (and still have) times when the car runs so atrociously with stumbles and misses that you figure a code would be thrown but NOOOO!! The only time I got a code was when I unplugged the throttle position sensor connector and turned the key on (to check voltage). Even before my second opti replacement, when the miss and stumble was extremely obvious, the dealer NEVER found a thrown code. It makes me wonder how bad do things have to get before the computer picks up a code.
Racer
Joined: May 2003
Posts: 304
Likes: 1
From: beaverton oregon
Though checking for codes first is always a good idea, I have to agree that some of the biggest PITA problems will show without a cold.
Really annoying, like being sicker then hell and not having a fever...
Really annoying, like being sicker then hell and not having a fever...
Drifting
Joined: Nov 2002
Posts: 1,593
Likes: 0
From: Mobile AL
St. Jude Donor '05
For three weeks after I first bought my car (with 90,000 miles on it) I'd get a Check Engine light, with "Muli-cylinder misfire" code. I changed everthing but my mind trying to find it. Three weeks later, I started looking at injectors and found that the #1 and #3 injector wires were reversed (#3 was on #1 and vice versa). After I changed them, have not gotten a code since. The strange thing is that it ran fine! Minor intermittent miss at idle (which I still have) but off idle it ran great. The computer in the car compensates so well for so many variables that it's hard to tell when you have a real problem unless it gives you a code (many of which are so vague as to be meaningless - "multi-cylinder misfire" - how many cylinders? which ones? fuel or electrical?) That's where the assistance of the folks on the forum comes in. Most everyone has had the same problems and joys with these wonderful cars. Good luck with finding the misfire. You might check the IAC as it can affect low speed driving and idle control.
Last edited by SilverBeast; May 19, 2005 at 11:49 AM.
Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
Originally Posted by SilverBeast
For three weeks after I first bought my car (with 90,000 miles on it) I'd get a Check Engine light, with "Muli-cylinder misfire" code. I changed everthing but my mind trying to find it. Three weeks later, I started looking at injectors and found that the #1 and #3 injector wires were reversed (#3 was on #1 and vice versa).
How did you figure out that the wires were reversed? Was it obvious by physical crossing of the wires?
Drifting
Joined: Nov 2002
Posts: 1,593
Likes: 0
From: Mobile AL
St. Jude Donor '05
The wires were just bent wrong - they just didn't look right. When I checked the color codes in the Helms manual, it indicated that they were crossed. All the other color codes on the other injectors were OK.
