95 LT-1 recently developed rough idle
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
95 LT-1 recently developed rough idle
Title says it all. After warming up when sitting at a stop, the car starts idling rough (automatic transmission) . Almost feels like a miss except that there is absolutely no indication of missing at normal driving conditions (as there was when I was having opti and plug problems). I will soon be bringing the car for minor service and a smog check at the dealer. What types of diagnosis can I expect (dirty IAC or something else in the fuel system?).
Thanks.
Thanks.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Re: 95 LT-1 recently developed rough idle (DougSilver)
It could be a intake manifold vacuum leak, or a fouled injector. Once the dealer gets it on the scope he can find it pretty fast.
Le Mans Master
Joined: Feb 2002
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Re: 95 LT-1 recently developed rough idle (DougSilver)
Welcome to the wonderful world of LT1 idle skip tracing. A lot of LT1's have a slightly skippy idle, then smooth out as soon as it goes beyond 1000 or 1100 rpm. My '95 has a slight skip that moves around at idle, but oddly mainly when idling in neutral or park-- in gear (auto trans) with the brake on the skip seems to go away. GM master tech has driven it, listened to it, scoped it, and finally proclaimed it to be "nc" on the service receipt (nc = normal condition), to quote from the receipt (was an add'l item to some ext warratny work) "Customer states a slight miss at idle. Found to be nc. Explained to cust."
If you don't have a good coating of dielectric grease on the inside of your coil wire boots and the plug wire boots (I take a q-tip and smear it on interior walls of the boots in a circular motion) it can cause a slight random skip. Of course there are many potential causes...
If you don't have a good coating of dielectric grease on the inside of your coil wire boots and the plug wire boots (I take a q-tip and smear it on interior walls of the boots in a circular motion) it can cause a slight random skip. Of course there are many potential causes...
Racer
Joined: Apr 2003
Posts: 260
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From: Palm Bay Fl
Re: 95 LT-1 recently developed rough idle (DougSilver)
My 1995 just started doing the same thing. I am wondering if it's a PCM virus set to go off at a certain date? :)
Once in a while when I start it I get a rough idle like a miss or something. But as soon as I start driving it goes away and stays away. It seems to only happen once in a while and only when I start it.
Strange. If I figure it out I'll let you know.
-Dave
[Modified by Dave C. '97 Z28, 7:23 PM 9/15/2003]
Once in a while when I start it I get a rough idle like a miss or something. But as soon as I start driving it goes away and stays away. It seems to only happen once in a while and only when I start it.
Strange. If I figure it out I'll let you know.
-Dave
[Modified by Dave C. '97 Z28, 7:23 PM 9/15/2003]
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
Re: 95 LT-1 recently developed rough idle (Dave C. '97 Z28)
a wondering idle is also the sign of a bad opti... but that would be followed with other problems, such as a big miss at throttle tip in...
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
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From: Encino CA
Re: 95 LT-1 recently developed rough idle (Dave C. '97 Z28)
I guess it just comes down to "American-car-itus" and was the one fear I had when getting the Vette after a 12-year period of owning Asian or German cars. The German cars were horrible in terms of upkeep but the Asian cars were flawless for all the years I owned them (10 years for Nissan Maxima, 6 years for Toyota Supra, and current Acura TL since 2000). How is it that the Asians can build decent performing cars that idle properly, don't rattle, and are reasonable to maintain? I wish I had a nickel for every post on the Vette forum that complains about poor idling, missing, bad opti, etc., etc., etc. It is really inexcusable for a car that is supposed to be top of the heap.
Team Owner
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From: Fort Knox, KY
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Re: 95 LT-1 recently developed rough idle (DougSilver)
When's the last time you cleaned your throttle body? That can make a huge difference in your idle characteristics. :thumbs:
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
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From: Encino CA
Re: 95 LT-1 recently developed rough idle (onedef92)
I suspect that is one of the services the dealer will recommend when I bring the car in. This was reportedly done one time before as part of a "fuel system service" but I found out that what the dealer considers throttle body cleaning is not the same as I would think. When I was told that they cleaned the throttle body, I could see that the screws were not even removed so I inquired as to what the cleaning consisted of. Seems they just spray some stuff into the throttle body. For what they were charging I would have expected at least a minor disassembly to clean interior parts.
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From: Fort Knox, KY
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Re: 95 LT-1 recently developed rough idle (DougSilver)
I suspect that is one of the services the dealer will recommend when I bring the car in. This was reportedly done one time before as part of a "fuel system service" but I found out that what the dealer considers throttle body cleaning is not the same as I would think. When I was told that they cleaned the throttle body, I could see that the screws were not even removed so I inquired as to what the cleaning consisted of. Seems they just spray some stuff into the throttle body. For what they were charging I would have expected at least a minor disassembly to clean interior parts.
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
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From: Encino CA
Re: 95 LT-1 recently developed rough idle (onedef92)
I days and cars gone by, I would often do the carburetor r&r myself and sort of enjoyed it. However, I always figured that since throttle bodies do not have anything going through them other than air, there was not as much need to clean compared with the jets and various passageways that carry fuel mixture in a carburetor--obviously I am incorrect.
Race Director
Joined: Sep 2002
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From: The third orange grove on the left
Re: 95 LT-1 recently developed rough idle (DougSilver)
I guess it just comes down to "American-car-itus" and was the one fear I had when getting the Vette after a 12-year period of owning Asian or German cars. The German cars were horrible in terms of upkeep but the Asian cars were flawless for all the years I owned them (10 years for Nissan Maxima, 6 years for Toyota Supra, and current Acura TL since 2000). How is it that the Asians can build decent performing cars that idle properly, don't rattle, and are reasonable to maintain? I wish I had a nickel for every post on the Vette forum that complains about poor idling, missing, bad opti, etc., etc., etc. It is really inexcusable for a car that is supposed to be top of the heap.
Le Mans Master
Joined: Feb 2002
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Re: 95 LT-1 recently developed rough idle (DougSilver)
What does that reply mean?
Sounds like the idle problem you describe is not the kind I described. Perhaps you have an identifiable malfunction that can be diagnosed.
As for so called asian car quality, I notice a lot of them throwing the old blue smoke out the tailpipe, and rarely see many of them on the road that are beyond 15 - 20 years old. Definitely looks like more old domestics avoid the scrap heap longer than Korean, Japanese imports. As a matter of fact, most every older Japanese sports car I see, 280Z, late 80's Supra's look ragged out and neglected... when you even see one on the road. But most of the older Vettes I see look in great condition.
Safety Car
Joined: Feb 2002
Posts: 4,212
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From: Sun City West Az
Re: 95 LT-1 recently developed rough idle (Lone Ranger)
I've been fighting the same rough idle miss at idle for about a year +. There is also an annoying pop in the exhaust at idle too. After a lot of parts and $ spent, I'm just living with it. Maybe it's just an "nc" condition. :D
Thread Starter
Burning Brakes
Joined: Feb 1999
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From: Encino CA
Re: 95 LT-1 recently developed rough idle (Lone Ranger)
Not sure what a "troll" is and don't get me wrong, I love the Vette. But as to overall quality compared with sticker price, the car has been a big disappointment--this was only offset by the fact that I got the car for $10k below sticker so can't complain about that.
But just scan the topics on this forum on any given day--rough idle, car won't start, windows rattle, poor performance due to (fill in the blank), cracks in body or top, etc.--need I say more?
As to the reason older Vettes look better than Japanese sports cars, I believe this is more a reflection on Vette owners than on the cars themselves. Someone finally buying an "icon" tends to baby it that much more. However, another tenant in the building I work in has a 93 that looks like crap--go figure.
But just scan the topics on this forum on any given day--rough idle, car won't start, windows rattle, poor performance due to (fill in the blank), cracks in body or top, etc.--need I say more?
As to the reason older Vettes look better than Japanese sports cars, I believe this is more a reflection on Vette owners than on the cars themselves. Someone finally buying an "icon" tends to baby it that much more. However, another tenant in the building I work in has a 93 that looks like crap--go figure.
