Misfiring and running rough - Help!
Thread Starter
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Joined: Jun 2010
Posts: 72
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Misfiring and running rough - Help!
A couple weeks ago, I noticed the Vette would kind of misfire at low RPM when the torque converter was locked up (like 1200 - 1500 RPM) and it would get under a load, but not enough to unlock the converter. That is getting progressively worse now. And also, after it does this a little bit, I can feel it stutter a little bit at an idle. It feels like a lean miss to me, but with a computer involved, it could be 100 things.
What I've done: It has a new (<9 months & 2K miles) MSD distributor. Also, I noticed the 2 vacuum lines that come off the thottle body and go to the canister were cracked so I replaced those last weekend. That didn't help. I don't really see any other vacuum sources. What else should I check? Any ideas would be great...
Thanks!
What I've done: It has a new (<9 months & 2K miles) MSD distributor. Also, I noticed the 2 vacuum lines that come off the thottle body and go to the canister were cracked so I replaced those last weekend. That didn't help. I don't really see any other vacuum sources. What else should I check? Any ideas would be great...
Thanks!
Racer
Joined: Oct 2010
Posts: 499
Likes: 0
From: Providence RI
Greg, you said you have changed the MSD so I would assume
you also changed out the plugwires, and plugs, and wire carriers.
but if you did not..and re-used your existing:
My 1994 LT-1 was doing the same, but I was reading some forum
info, and one thing was, to put the car in the garage, with exhaust
vented, hood up, and turn off all the lights. look at both sides of your engine plug wiring.
man..I saw a lightning show, number 2 wire arcing, plugs arcing,
all kinds of grounding issues. both sides of the block. I have not
attempted any fix yet, but I am going to replace all plugs, wires
carriers, keep everything away from metal grounds, and heat
and do this again, I was astounded that in all my years I never
did this before, and I could not believe what I was seeing..
take a grease pencil into the dark with you..and put mark
where see arcing..replace that stuff!! My wires are currently so bad
if I lay the shaft of a screwdriver over the 2 wire..I can arc it to the block! fortunately..car is currrently a work in progress,and once
I resolve all these lil fun items, she should be good.
Best to You, Derek
you also changed out the plugwires, and plugs, and wire carriers.
but if you did not..and re-used your existing:
My 1994 LT-1 was doing the same, but I was reading some forum
info, and one thing was, to put the car in the garage, with exhaust
vented, hood up, and turn off all the lights. look at both sides of your engine plug wiring.
man..I saw a lightning show, number 2 wire arcing, plugs arcing,
all kinds of grounding issues. both sides of the block. I have not
attempted any fix yet, but I am going to replace all plugs, wires
carriers, keep everything away from metal grounds, and heat
and do this again, I was astounded that in all my years I never
did this before, and I could not believe what I was seeing..
take a grease pencil into the dark with you..and put mark
where see arcing..replace that stuff!! My wires are currently so bad
if I lay the shaft of a screwdriver over the 2 wire..I can arc it to the block! fortunately..car is currrently a work in progress,and once
I resolve all these lil fun items, she should be good.
Best to You, Derek
A couple weeks ago, I noticed the Vette would kind of misfire at low RPM when the torque converter was locked up (like 1200 - 1500 RPM) and it would get under a load, but not enough to unlock the converter. That is getting progressively worse now. And also, after it does this a little bit, I can feel it stutter a little bit at an idle. It feels like a lean miss to me, but with a computer involved, it could be 100 things.
What I've done: It has a new (<9 months & 2K miles) MSD distributor. Also, I noticed the 2 vacuum lines that come off the thottle body and go to the canister were cracked so I replaced those last weekend. That didn't help. I don't really see any other vacuum sources. What else should I check? Any ideas would be great...
Thanks!
What I've done: It has a new (<9 months & 2K miles) MSD distributor. Also, I noticed the 2 vacuum lines that come off the thottle body and go to the canister were cracked so I replaced those last weekend. That didn't help. I don't really see any other vacuum sources. What else should I check? Any ideas would be great...
Thanks!
Thread Starter
Advanced
Joined: Jun 2010
Posts: 72
Likes: 0
Greg, you said you have changed the MSD so I would assume
you also changed out the plugwires, and plugs, and wire carriers.
but if you did not..and re-used your existing:
My 1994 LT-1 was doing the same, but I was reading some forum
info, and one thing was, to put the car in the garage, with exhaust
vented, hood up, and turn off all the lights. look at both sides of your engine plug wiring.
man..I saw a lightning show, number 2 wire arcing, plugs arcing,
all kinds of grounding issues. both sides of the block. I have not
attempted any fix yet, but I am going to replace all plugs, wires
carriers, keep everything away from metal grounds, and heat
and do this again, I was astounded that in all my years I never
did this before, and I could not believe what I was seeing..
take a grease pencil into the dark with you..and put mark
where see arcing..replace that stuff!! My wires are currently so bad
if I lay the shaft of a screwdriver over the 2 wire..I can arc it to the block! fortunately..car is currrently a work in progress,and once
I resolve all these lil fun items, she should be good.
Best to You, Derek
you also changed out the plugwires, and plugs, and wire carriers.
but if you did not..and re-used your existing:
My 1994 LT-1 was doing the same, but I was reading some forum
info, and one thing was, to put the car in the garage, with exhaust
vented, hood up, and turn off all the lights. look at both sides of your engine plug wiring.
man..I saw a lightning show, number 2 wire arcing, plugs arcing,
all kinds of grounding issues. both sides of the block. I have not
attempted any fix yet, but I am going to replace all plugs, wires
carriers, keep everything away from metal grounds, and heat
and do this again, I was astounded that in all my years I never
did this before, and I could not believe what I was seeing..
take a grease pencil into the dark with you..and put mark
where see arcing..replace that stuff!! My wires are currently so bad
if I lay the shaft of a screwdriver over the 2 wire..I can arc it to the block! fortunately..car is currrently a work in progress,and once
I resolve all these lil fun items, she should be good.
Best to You, Derek
Plugs are fairly old (bought new ones, but haven't put them in yet). The wires are probably in the 1-2 year range, but I'm going to check them out. Am I correct that they are a B..... to connect to the distributor? This is what has kept me from tackling this up until now.
Melting Slicks
Joined: Oct 2005
Posts: 3,178
Likes: 5
From: Daleville Indiana
St. Jude Donor '08
Does it misfire when cold or only after to warms up. If so it could be the ICM. After I put on the MSD opti mine started to over heat and need to be moved a way for the heads for better cooling.
Thread Starter
Advanced
Joined: Jun 2010
Posts: 72
Likes: 0
It does it more when it is hot, or at least warmed up. However yesterday it was almost contstant from the time I started driving. Looks like I will fight through doing the plugs and wires just so if I have to take it in, some yahoo doesn't charge me $500 to do it.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
It does it more when it is hot, or at least warmed up. However yesterday it was almost contstant from the time I started driving. Looks like I will fight through doing the plugs and wires just so if I have to take it in, some yahoo doesn't charge me $500 to do it.
Good idea. Do it yourself and save $$$ and also you'll be sure it was done correctly.
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