Running rough after 30 minutes
Thread Starter
4th Gear
Joined: Feb 2022
Posts: 4
Likes: 0
From: Texas
Running rough after 30 minutes
Tech question. I would like to know what to start looking for. I drove my girl (1993 with the lt1) today and after about 30 mins of normal driving she start to run really rough. No power at all. Pulled over and waited for my ride to go get my truck and trailer. After about 40 mins I started her up to move her to a better spot and she was running great. But again after 30 minutes same problem. Any help would be great.
Melting Slicks
Joined: Feb 2015
Posts: 2,069
Likes: 262
From: Park Ridge New Jersey
Tech question. I would like to know what to start looking for. I drove my girl (1993 with the lt1) today and after about 30 mins of normal driving she start to run really rough. No power at all. Pulled over and waited for my ride to go get my truck and trailer. After about 40 mins I started her up to move her to a better spot and she was running great. But again after 30 minutes same problem. Any help would be great.
I found it
https://www.corvetteforum.com/forums...park-help.html
hope that sheds some light
Team Owner
Joined: Sep 2001
Posts: 62,162
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Sounds like a closed loop operation issue if it only starts after the engine is warm. After another successive start, there is a timer based on coolant temp before closed loop begins again.
Is any code being set via SES light?
Could be several things, O2 sensor failure would cause it to run pig rich and stumble, for example.
Is any code being set via SES light?
Could be several things, O2 sensor failure would cause it to run pig rich and stumble, for example.
Team Owner
Joined: Sep 2001
Posts: 62,162
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
But EGR will not activate until coolant reaches 170 and you're at <70% throttle for a period of time, its only initially supposed to turn on in cruising conditions. That it closes and she starts up and runs fine cold tends to preclude this, EGR usually always sets a code quickly too.
Thread Starter
4th Gear
Joined: Feb 2022
Posts: 4
Likes: 0
From: Texas
If the EGR is stuck open it can, or some other vac leak.
But EGR will not activate until coolant reaches 170 and you're at <70% throttle for a period of time, its only initially supposed to turn on in cruising conditions. That it closes and she starts up and runs fine cold tends to preclude this, EGR usually always sets a code quickly too.
But EGR will not activate until coolant reaches 170 and you're at <70% throttle for a period of time, its only initially supposed to turn on in cruising conditions. That it closes and she starts up and runs fine cold tends to preclude this, EGR usually always sets a code quickly too.
5th Gear
Joined: Apr 2020
Posts: 5
Likes: 1
From: Warren, Michigan
I changed Idle Air Control valve, MAF sensor, even tried plugs and wires. Unfortunately nothing changed.
I dont want to be the one to say it, but for me it was my opti-spark. Once I changed it, I havent seen an issue with the vehicle since. Hopefully this helped, I know its the word all of us C4 owners hate to hear, but the Opti spark really is the culprit for a large amount of issues for us.
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Thread Starter
4th Gear
Joined: Feb 2022
Posts: 4
Likes: 0
From: Texas
Work completed
Thank you everyone for the info. I went ahead and replaced the optispark and everything else associated with it. Plugs, wires, coil, ICM, water pump and belt. She is running better than ever. But took her out last night for a nice ride and she run with no issues.