Rough idling 90 C4
Thread Starter
Cruising
Joined: Dec 2021
Posts: 10
Likes: 2
From: Pittsburgh
Rough idling 90 C4
Hello,
I recently purchased a 1990 Corvette with 56K and have been going through it fixing what I can. I did a tune up where I replaced the spark plugs, wires cap, rotor. and fuel filter. I still have a slight miss where around 1500 RPMS she really bogs when driving. At idle the car runs OK but occasionally slight dips in rpm almost to stall. I pulled codes from the car but none seem to pertain to anything related to the drivetrain, as far as I can tell ( H13,H72,H74). I don't recall the car doing this on the drive home after purchase but it was there before the tune up. I am wondering if its a clogged injector or fuel pump\ sock issue in the tank. I'm not a mechanic and know little regarding the vette but I have always wanted one of these cars since this gen came out so I dont mind working on her.
Let me know what you think and if you have any suggestion as to where to look next .
Thanks in advance.
I recently purchased a 1990 Corvette with 56K and have been going through it fixing what I can. I did a tune up where I replaced the spark plugs, wires cap, rotor. and fuel filter. I still have a slight miss where around 1500 RPMS she really bogs when driving. At idle the car runs OK but occasionally slight dips in rpm almost to stall. I pulled codes from the car but none seem to pertain to anything related to the drivetrain, as far as I can tell ( H13,H72,H74). I don't recall the car doing this on the drive home after purchase but it was there before the tune up. I am wondering if its a clogged injector or fuel pump\ sock issue in the tank. I'm not a mechanic and know little regarding the vette but I have always wanted one of these cars since this gen came out so I dont mind working on her.
Let me know what you think and if you have any suggestion as to where to look next .
Thanks in advance.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Those cars with that age are known for bad fuel injectors. Bad idling, acceleration, fuel economy and power. I would just replace them or at least get them professionally tested for spray pattern and flow.
1st Gear
Joined: May 2022
Posts: 1
Likes: 0
Check the code history. I wrestled with a hesitations, bogging, backfiring, rough running engine for two weeks before finding that the coolant temp sensor was causing all of my problems. Once replaced the engine ran perfectly!
