Rough serging idle
Thread Starter
Heel & Toe
Joined: Jun 2009
Posts: 20
Likes: 0
From: Ontario
Rough serging idle
I have a 1994 corvette. Once it warms up it starts to idle rough and hesitation on ecceleration and if I’m stopped at a light or even in park the rpm serges as well i have done a complete tune up, new water pump new alternator ,oxygen sensors, pvc,fuel injection pressure regulator, tps,iac, egr valve, and repaired a vacuum leak. Not sure what to do next. Car runs great when it’s cold.
Last edited by loucazo; Oct 15, 2021 at 05:57 AM.
Intermediate
Joined: Jul 2014
Posts: 32
Likes: 3
From: State College Pennsylvania
I have experienced similar rough idling in my 1994 LT1 also. This must have been a common problem for this model because the manufacturer even addressed this issue on page 46 of the owner's manual. It basically states that the oxygen sensors may be clogged. The manufacturer's solution is to "1. Set the parking brake. 2. Shift an automatic to (Park) or a manual transmission to (Neutral) . 3. Press the accelerator until your tachometer reads 2,000 rpm and hold for two minutes." Hope this helps your problem, it did for me and I have to preform this procedure yearly when I first take my car out of winter storage.
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
One of THEE best things I did when I bought my 95 C4 was to buy an OBD-I scanner! I was experiencing a similar issue as yours with mine. And, when I took it to a dealer to have it fixed, it came back "no problem found" with a bill for $200 labor. But, on the drive home, the issue was obviously still there. That was the when I quit throwing parts at it and bought the scanner.
It only took a few minutes cruise w/ the scanner running when BINGO! the problem occurred and I pressed the "store" button on the scanner. It only took a few seconds to see what was going on - (in my case) it was the right side O2 was intermittently dropping out and the computer responded by jumping the injector dwell to 90% on the right bank (25% on the left bank w/ the O2 in the mid range). With the scanner - NO MORE throwing parts at it and hoping to get lucky!!
Best money/tool I ever spent!
It only took a few minutes cruise w/ the scanner running when BINGO! the problem occurred and I pressed the "store" button on the scanner. It only took a few seconds to see what was going on - (in my case) it was the right side O2 was intermittently dropping out and the computer responded by jumping the injector dwell to 90% on the right bank (25% on the left bank w/ the O2 in the mid range). With the scanner - NO MORE throwing parts at it and hoping to get lucky!!
Best money/tool I ever spent!
Safety Car
Joined: Dec 2015
Posts: 3,947
Likes: 1,407
From: Canada
One of THEE best things I did when I bought my 95 C4 was to buy an OBD-I scanner! I was experiencing a similar issue as yours with mine. And, when I took it to a dealer to have it fixed, it came back "no problem found" with a bill for $200 labor. But, on the drive home, the issue was obviously still there. That was the when I quit throwing parts at it and bought the scanner.
It only took a few minutes cruise w/ the scanner running when BINGO! the problem occurred and I pressed the "store" button on the scanner. It only took a few seconds to see what was going on - (in my case) it was the right side O2 was intermittently dropping out and the computer responded by jumping the injector dwell to 90% on the right bank (25% on the left bank w/ the O2 in the mid range). With the scanner - NO MORE throwing parts at it and hoping to get lucky!!
Best money/tool I ever spent!
It only took a few minutes cruise w/ the scanner running when BINGO! the problem occurred and I pressed the "store" button on the scanner. It only took a few seconds to see what was going on - (in my case) it was the right side O2 was intermittently dropping out and the computer responded by jumping the injector dwell to 90% on the right bank (25% on the left bank w/ the O2 in the mid range). With the scanner - NO MORE throwing parts at it and hoping to get lucky!!
Best money/tool I ever spent!
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Unfortunately, my AutoXray (far as I know) is out of business. However, there are a few Tech-Is we see offered on this and other FORUMS. And, AutoZone may be able to scan OBD-I, and possibly source one.
Sorry I couldn't be more help. But, keep an eye out for Tech-I or another OBD-I capable unit. You won't regret it!
Sorry I couldn't be more help. But, keep an eye out for Tech-I or another OBD-I capable unit. You won't regret it!
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