Pre ignition

1st Vette

1st Vette

Gato Tranquilo
Staff member
Power User
Moderator
Mega Donor Summer Award Limited Big Donner Mod Peacemaker Seriously Rich
Messages
11,011
Reaction score
20,150
VetteCoins
282,714
Car
2024 C8 coupe
Province
NT
The dreaded rattle. I have access to 91 octane fuel only in my area . I have been using only Shell Top Tier 91 since new mostly except while traveling, but always at least 91 and always Top Tier . Yesterday while going to move to the right hand lane while in 4th gear at about 1400 pm I noticed the blind spot lights come on in my right mirror and gave it some gas to quickly get ahead of the vehicle beside me . And then heard very distinctly the dreaded "rattle" . First and only time it has happened.
Has anyone else experienced this ? And is anyone aware of an octane additive that is " approved " for use in the LT2 engine ? And if so have any of you used one . Thanks .
I should add that I was in auto mode which I do infrequently, usually always in manual and generally keeping the RPM up . So , although I didn't notice I am pretty sure it would have been in 4 cylinder mode at the time .
 
cdnz said:
DRIVE IN MANUAL MODE. LOL....
4cly at 1400 rpms. 😬
Click to expand...
Believe me , 98% of the time I do . I never let the engine lug . Don't forget that supposedly the ECM won't allow the engine to lug either according to what the engineers/programmers feel is too low . Next time you are in manual mode at 1500 RPM try to up shift .... it won't. Same as trying to downshift at higher RPM , it won't let you.
 
I suspect you fooled the tranny. It's happened to me occasionally where the car was in the wrong gear when I went to pass. I had been slowing down behind a slow car and the tranny obviously was down a gear, but I sped up a little to check for the pass and the alternate clutch went up a gear and I bogged when I gave it gas. I didn't notice a rattle though.
 
Murray20c8 said:
I suspect you fooled the tranny. It's happened to me occasionally where the car was in the wrong gear when I went to pass. I had been slowing down behind a slow car and the tranny obviously was down a gear, but I sped up a little to check for the pass and the alternate clutch went up a gear and I bogged when I gave it gas. I didn't notice a rattle though.
Click to expand...
They will sometimes do that if you are in manual and you happen to pull the left paddle just as the ECM decided it's time to go down a gear like from third to second and you end up in first if the revs are low enough, because of the timing . In manual as you have probably noticed the TX will down shift when the revs drop low enough whether you pull the paddle or not . This though was a definite pre ignition rattle. Very distinct . Not odd shift point related I'm afraid.
 
1st Vette said:
They will sometimes do that if you are in manual and you happen to pull the left paddle just as the ECM decided it's time to go down a gear like from third to second and you end up in first if the revs are low enough, because of the timing . In manual as you have probably noticed the TX will down shift when the revs drop low enough whether you pull the paddle or not . This though was a definite pre ignition rattle. Very distinct . Not odd shift point related I'm afraid.
Click to expand...
I meant that when the car bogs you can get piston rattle
 

Similar threads

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)
Back
Top