rough idle in 90' L98
Thread Starter
Advanced
Joined: Apr 2004
Posts: 91
Likes: 0
From: Warrenton Virginia
rough idle in 90' L98
I have been getting my 90' out of its winter hibernation mode for some quick drives when the weather is permitting. Lately I have noticed it will idle a little rough and stumbles on acceleration. I pulled one of the plugs and it looked fine. This car may see 5-8 K miles per year. It currently has 35K. After I got the car a few years back I tuned it up and it was running pretty good but I noticed an occasional rough idle. Should I be changing my plugs on a more often basis or am I looking at another problem? The motor is basically stock with the exception of a high energy coil and MSD wires. It also has the K&N air filter and modified air box. Any help would be greatly appreciated. Thanks Steve
Pro
Joined: Sep 2006
Posts: 702
Likes: 2
From: Conyers Ga
Before tearing into it, my first step would be a can of fuel injector cleaner and then run it like you stole it. Check the TB and clean as necessary. Then check the voltage on the TPS. If, after these few things it still idles rough then we can get into it deeper..ie: 02's.....IAC's and so on............
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
I would be very concerned with placing fuel injector cleaner in a car with the GM Multec injectors (years 89 thru 91). This can cause shorting of wire turns in the injector coils. Been there, done it with my 89.
Thread Starter
Advanced
Joined: Apr 2004
Posts: 91
Likes: 0
From: Warrenton Virginia
rough idle in 90 L98
Guys thanks for the replys so far. The car always had a bit of a rough idle. Even during the summer when I drove it a lot more. I have run some injector cleaner thru it in the past which didnt seem to make much difference. As stated before, the plugs and wires were replaced about 5K miles ago along with the coil and cap. I pulled one plug out of the DS bank and found it clean and gapped about .040. I am using an accel High output coil. I ran a scan on it and found no codes at all. I am wondering about the ignition module. I read "after " I replaced coil and cap that they reccomend replacing the module with the other parts. Typical vendor propaganda which I didnt pay much attention to. What I notice the most is that if I am cruising at a steady speed and hit the throttle there is a slight hesitation or surge. Any direction you could point me would be great. Again thanks for the help. Steve
Thread Starter
Advanced
Joined: Apr 2004
Posts: 91
Likes: 0
From: Warrenton Virginia
I have put this issue on hold since I am trouble shooting a no horn problem also. I will clean the TB and look at the IAC , I dont beleive I have ever cleaned it since I have owned it. It has 35K miles on it and I have kept up on the routine stuff and I run a can of 44K thru it once a year. I cleaned the TB last summer it was a little dirty , not bad though. I will keep you posted about my prThanks for the feedback.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
