Heyall
I've got a 1998 with ~102k miles, no mods. Starting in september of last year (1 day) it did this shaking at idle/smells like gas thing, but then it went away after a day. Skip forward a few months and it happened again, for a bit longer. I took it in to two different mechanics, both scanned it but it wouldnt replicate the problem for them so they couldnt do much.
Forward to recently, it did it again (5 days before my warranty expired), check engine light came on, got it looked at...it was shaking and threw a service traction control system error, but he cleared that and ran it for a while and as the mechanic was inspecting it, started working fine again!!!

Needless to say, my extended warranty is finished and now the problem is back figures. So just wondering, this could happen if an injector or coil was going bad, right? And if so, would it throw any codes?

As of now, its still shakes at idle occasionally, misses even at highway speeds occasionally (noticeable hesitation), but no check engine light, no codes at all. It smells like gas (like burned +gas, incomplete combustion type smell i guess) out of the exhaust about 65% of the time.

Plugs and wires are brand new (first thing i changed when it started to happen), always run on 91 chevron, tried to use sea foam (didnt do much), later tried a bottle of techron (nothing). So at this point, i'm lost...if a mechanic refuses to take your money (can't diagnose it so cant fix it)...maybe its a sign from the gods that the car wants to just die???

any suggestions/ideas? or, anyone wanna buy it?...

 

First thing to do is pull the codes and post them up and we can go from their.

 

Thats the thing man, NO CODES using the onboard reader
thats whats driving me nutts!

 

Kind of hard to believe that there are no codes. A history code could tell you what the issue is and it could be a code that is not a pxxxx code. Post them up.

It coud be a LOT of things, and almost all will set some kind of code. If the condition clears, like you are saying the code could become a history code.

Any work done on the car prior to the issue starting? Could help issolate the problem.

 

You need to find a shop that specializes in Vettes .

Let them hook it up to HP Tuners and do a realtime scan on the street of what is going on.

Before you do that, you mentioned you changed your plugs and wires! Have you since pulled them again to see if one or more are wet and if so which one. This will help you isolate the bank and either the injector or wire or cylinder that is giving you trouble.

Make sure you pull them after it was shuttering/running but making sure you let it cool down to a reasonable degree (No burns ) - Which plugs are you running currently and at what gap?

As far as the wires go I would check these with an Ohm meter and see it there is any that have a lot of reistance, this would help you make sure the wires are working properly - Which wires are you running currently?

Thanks,Matt

 

There a LOTS or reasons for rough running that will NOT throw a code, leaky injectors, vacuum leaks, marginal plug(s)/wire(s).

 

I had Top Flight in SD look at it both times and he actually drove it around with a scanner attached WHILE the problem was going on and it wasn't consistently displaying a specific misfire or anything.
The issue started before i did the plugs/wires (that was an attempt to correct it), but i'll go thru and check everything out again. They're stock delco brand new plugs and wires btw

they just told me to continue driving it till it becomes a consistent problem, ie something goes bad so they can fix it...i just smell exhaust fumes and stuff on occasion when it runs rough so i'm concerned its taking a toll on my cats or something.

driving it today it started out with a rough idle but became smooth once i hit it a bit and stayed smooth at red lights from that point on

ugh i dont know what to do even if it isnt a big deal in the long run its still embarrassing to have a vette that spazzez out every so often

 

Some LS1's have been known to have rocker arm/vlave spring issues "issues", these won;t throw a code till something BAD happens. Might be woth pulling the valve covers for some recon.

 

More info plz, what do i do?? this sounds like it could get costly if i let it be HELP!

 

When you change the plug wires, you should be able to feel the wire seat fully on the plug. When you attach the upper end, you should feel it snap twice. Might want to recheck the wires.

 

yep checked the wires earlier today, everything is tight
if it were the plugs or wires, the problem would likely be consistent though, right?

this animal comes and goes, most obvious right when i start the car and put it in gear, once it goes over ~1300rpm (parking lot acceleration, nothing crazy) it stabilizes and stays pretty solid for the most part, just the occasional spazzing out and startup troubles

 

Could be a vacuum leak or unmetered air entering before the Throttle body-this is the most likely suspect. The valve spring/rocker problems are fairly well documented here, do a search. The springs can break and the rockers can loose their needle bearings causing 1 or more cylinders to start acting up.

 

I am having the same problem and would like to know what the fix was seeing this thread is over a month old.
Thanks

 

Hey there
I've just been driving it as is (shaking etc) for the past month or so and the problem didnt get any worse, i've filled up gas again twice and both times i used chevron 91 and added an extra bottle of their techron additive (its supposedly a good injector cleaner based on what i've read).
Anyway, i'm on tank #3 since the problem started now and call it a miracle but its running fine, no more shakes (not even occasionally) just plain and simple smooth!!!

My hypothesis is that the fuel injectors or other fuel component is starting to go bad, so using bad gas (i filled up at a no-name gas station once, i'm thinking that mightve done it) causes the fuel system to go haywire. I know that this also causes the fuel gauge to drop to empty spontaneously too and to fix that i had been using chevron 91 as well.

So its probably the gas, my car used to sit for long periods (2 weeks at a time) but i recently started a job in addition to school which i drive to every couple days so i think increased driving frequency plus the better gas and cleaner helped to clear up the problem for me... but as soon as i have a few days i'm planning to ship the injectors off to be cleaned up as i believe that their deterioration or buildup on them might be the primary cause.

Good luck man, i hope your fix is as easy as mine...and free too!! take care

 

Chate
I have found what seems to be a common problem to cause the same issues you describe, with the exception of the gas smell. And from what I have read, it happens to cars with or without headers.
I have been all over my car looking for a problem, and what I found last night is the wires running right beside the Starter have melted together causing a short. I have 3 wires burnt together, and the weird thing is that my surging, hesitating, or whatever you want to call it would come and go.
It's worth taking a look at.
Those wires in the small plastic tubes go to the 02 sensors and the crank sensor from what I am told.
Good luck