Detonation Issue on my LS1
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 6,507
Likes: 723
From: Sausalito CA
Detonation Issue on my LS1
Hello,
1999 LS1 - A4 - Vert: Blackwing, alum. MAF ends, silicon coupler, MSD 8.5 plug wires, shorty headers, x-pipe, Ti mufflers. Else all stock.
On one run on a dyno at approximately 5000 to 5200 rpm I experience detonation (graph shows three negative spikes).
Second run at approximately 5200 to 5300 (graph shows one negative spike).
Driveability, I do not notice or hear a problem at those rpms...the problem is diagnosed/ apparent from the dyno graph only.
Unfortunately, I can not post a picture of the dyno graphs.
Since car is on warranty, off to the competent dealer. They can not find any thing wrong. No sensors issue, no codes no obvious issues.
So co-members, help, what do you think could be the issue?
(Weak coils, air leak at silicon coupler, spark plug wire, oil getting into cylinder)
Again on the road, I do not hear or feel anything wrong.
1999 LS1 - A4 - Vert: Blackwing, alum. MAF ends, silicon coupler, MSD 8.5 plug wires, shorty headers, x-pipe, Ti mufflers. Else all stock.
On one run on a dyno at approximately 5000 to 5200 rpm I experience detonation (graph shows three negative spikes).
Second run at approximately 5200 to 5300 (graph shows one negative spike).
Driveability, I do not notice or hear a problem at those rpms...the problem is diagnosed/ apparent from the dyno graph only.
Unfortunately, I can not post a picture of the dyno graphs.
Since car is on warranty, off to the competent dealer. They can not find any thing wrong. No sensors issue, no codes no obvious issues.
So co-members, help, what do you think could be the issue?
(Weak coils, air leak at silicon coupler, spark plug wire, oil getting into cylinder)
Again on the road, I do not hear or feel anything wrong.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Detonation Issue on my LS1 (Kenny94945)
These cars are very prone to carbon build-up. You may want to run GM carbon cleaner in your fuel, part # 12345515 for several tanks and then try it again.
Le Mans Master
Joined: Oct 1999
Posts: 8,205
Likes: 40
From: Tucson AZ
Re: Detonation Issue on my LS1 (vettenuts)
These cars are very prone to carbon build-up. You may want to run GM carbon cleaner in your fuel, part # 12345515 for several tanks and then try it again.
Drifting
Joined: May 2002
Posts: 1,607
Likes: 1
From: San Francisco CA
Re: Detonation Issue on my LS1 (Kenny94945)
My guess is that with your mods, you are running too lean. You need to dyno the car where they have wideband O2 and can graph your A/F ratio. If they had the abiltity to take traces of you car as well that would be a plus. Traces would show your fuel trims, timing, knock retard, etc.
Racer
Joined: Apr 2002
Posts: 336
Likes: 0
From: Willow Springs IL
Re: Detonation Issue on my LS1 (SFVetteman)
:iagree:
He's right. Without that information it's hard to diagnose your exact problem. Those spikes could be just ignition problems or, if the car didn't buck on the dyno, it might be the dyno's tach lead wires messing up and not your problem at all.
He's right. Without that information it's hard to diagnose your exact problem. Those spikes could be just ignition problems or, if the car didn't buck on the dyno, it might be the dyno's tach lead wires messing up and not your problem at all.
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 6,507
Likes: 723
From: Sausalito CA
Re: Detonation Issue on my LS1 (Kenny94945)
Thank you all...good leads.
Carbon, lean, dyno error. To repete even with this issue the Corvette is a good car and fun to drive.
Carbon, lean, dyno error. To repete even with this issue the Corvette is a good car and fun to drive.
