Acceleration
Thread Starter
Cruising
Joined: Oct 2021
Posts: 11
Likes: 1
From: New Orleans
Acceleration
Hi y’all . Just bought first corvette. 96 Lt1. So I put new opti plugs wires coil . Runs great till you start to get on it. Doesn’t do it all the time just once I a while. You start to get in it a lil and it bogs let out and get right back in it and it takes off. Get to the red light and it idles real rough for a while have to play with the gas a lil to get it to move. If you kill it it starts back up and runs fine for a while. I did notice if you stay in it when it bogs it pops under the hood like it’s back firing threw a carburetor. The other thing don’t know if it has anything to do with it but for a while I would hear the whoosh when I took off the gas cap. I didn’t hear it for a while. It made the whoosh sound this morning but that’s the first time in a month. Any help will be appreciated. This corvette is a lil different to work on then I’m use to lol. Thanks. Not throwing any codes or lights on dash
Last edited by daddyquack; Oct 11, 2021 at 08:27 AM.
Instructor
Joined: Aug 2016
Posts: 209
Likes: 24
I'm interested in this one as well. I suspect we are having similar issues. Mine only happens when it's real hot like 95 outside and the car has been running around 205 degrees for a while. It runs just fine while it's running but, If I stop and shut the car off it will start again but not really run. Will not rev and will stall if you touch the gas and idles like it is on 3 cylinders. If I let it sit for a couple of hours (which sucks if you are on the side of the road) it will start up and run just fine. When it's cool outside it idles, revs, and has great power all the way to the red line so I don't think it's an opti issue. I'm leaning towards the Ignition Control Module. Hopefully someone with more experience then I have will chime in and point us in the right direction.
Advanced
Joined: May 2021
Posts: 85
Likes: 29
From: Concord, CA
Double check you wired the new ignition wires right. I had kind of a similar issue where it would miss or bog under loaded acceleration, but a new opti from autozone fixed mine. (also changed wires at the time). New plugs are all gapped correctly? I think you can check all the injectors for the proper resistance to confirm they are all okay. Just throwing some ideas out there - haven't had to do a ton of diagnosis on mine. (92 LT1).
On second thought.. With OB2 you'd probably get codes if you didn't wire the opti correctly to the right cylinders... You have all good and fresh gas? With my car, I ran some seafoam and injector cleaner for the first couple tanks of gas because the car had been sitting for a long time. Don't know your car's history.
On second thought.. With OB2 you'd probably get codes if you didn't wire the opti correctly to the right cylinders... You have all good and fresh gas? With my car, I ran some seafoam and injector cleaner for the first couple tanks of gas because the car had been sitting for a long time. Don't know your car's history.
Le Mans Master
Joined: Oct 2004
Posts: 7,706
Likes: 485
From: Everett WA
C4 of Year Finalist (appearance mods) 2019
Welcome to the forum and the wonderful world of C4 corvettes.
If this is your first C4 I hope that you kept the opti that you took out of the car. If it's the original OEM unit it can be rebuilt to be a more reliable unit that most anything that you can buy at a auto parts house today.
You indicate that you have no lights flashing on the dash but ..... do you know how to pull actual trouble codes out of the system using the paper clip method and the ALDL plug?
If this is your first C4 I hope that you kept the opti that you took out of the car. If it's the original OEM unit it can be rebuilt to be a more reliable unit that most anything that you can buy at a auto parts house today.
You indicate that you have no lights flashing on the dash but ..... do you know how to pull actual trouble codes out of the system using the paper clip method and the ALDL plug?
Thread Starter
Cruising
Joined: Oct 2021
Posts: 11
Likes: 1
From: New Orleans
No I haven’t tried to pull codes that way but I did have the mechanic I work with plug into it and no codes or even stored codes. I did change the fuel filter today. Had some grit in it . Ran and idled fine one small drop off on the ride home was wondering if that could have been a lil air or something I had just changed filter and took off. The guy before me was second owner. He had the car 11 years put 30 k on the car but couldn’t tell me much about it other then he put a new battery and had just had fuel pump replaced. Other then that he hadn’t done anything else but oil changes. Car had a 114k when I got it.
Thread Starter
Cruising
Joined: Oct 2021
Posts: 11
Likes: 1
From: New Orleans
So today I stoped and got fuel fuel pressure tester and road home with it hooked up. Turn key on get 48 psi spike drops to 43 psi . Turn key off holds 43 . Start car to come home pressure sits about 38. Start running it I see spike over 50 let out of it drops to as low as 30. Stop at red light it idles about 35 psi. Does any one know if those numbers are good seems low and all over the place to me ...
Drifting
Joined: Mar 2018
Posts: 1,361
Likes: 400
From: DFW TX
Since you changed out all the plugs and wires, that is where I would look first. A cracked plug or loose wire at the plug will cause stumbles and backfires like you describe. Especially when hot and under heavy load.
Burning Brakes
Joined: Apr 2014
Posts: 829
Likes: 192
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Burning Brakes
Joined: Apr 2014
Posts: 829
Likes: 192
So today I stoped and got fuel fuel pressure tester and road home with it hooked up. Turn key on get 48 psi spike drops to 43 psi . Turn key off holds 43 . Start car to come home pressure sits about 38. Start running it I see spike over 50 let out of it drops to as low as 30. Stop at red light it idles about 35 psi. Does any one know if those numbers are good seems low and all over the place to me ...
Thread Starter
Cruising
Joined: Oct 2021
Posts: 11
Likes: 1
From: New Orleans
Thanks y’all . Well I bought a scanner ran it I the car for a while and no codes. Did a lot of reading in here ( first vet trying to learn) went out unplugged the MAF and no change in the idle didn’t die and ran way better. Bought a new MAF car was running amazingly but a rough idle and very slight bog. Got to looking again and found crack in brake power booster . Now WOW this thing runs it’s butt off. Hasn’t ran like this sense I bought it. Didn’t know it would run this way.
