I take it the goal is not to have any pre-ignition whatsoever? Not even a "ping or two" while accelerating wide open throttle.....or "lugging it" up a steep grade?

Even a little ping, once in a while, is doing some damage to the pistons, right?

Just checking.

 

Well, I just learned that mine had quite a bit of knock retard due to pinging with the factory program. Now I have a custom tune and no pinging. I think the motor will protect itself pretty well, mine even jumped to the low octane table in the PCM when things got really bad.

 

Hmmm, mine pings too and it's stock except for a Blackwing and Corsa exhaust. The dealer found nothing wrong with it and suggested I retard the timing. But then the guys here say they have had no problems with theirs pinging, even on 91 gas.

I finally had one mechanic tell me that "a little pinging is alright" and won't hurt anything.

I don't believe it and figured I'd better check it out here.

 

There is no such thing as good pre-ignition. People running 91 octane gas and say they have no ping, just dont know what ping is.. once these LS1 motors get some miles on them the carbon build up increases the CR. if you retard the spark you lose HP, but if your have pre-ignition you get automatic KR and you lose HP.

 

Hmmm, so what you're saying is that I should not hear any pre-ignition pinging, since the onboard computer will compensate for it?

I take it that C5's have a "knock sensor" like that which is on the LT1 c4's? So therefore, if I am hearing pre-ignition pinging, that means I must have a defective knock sensor, right?

 

Pinging is light pre-ignition. Knock is heavy denotation and that's what the knock sensor is looking for. Spark knock is just that, sharp hard knocking (in effect dieseling) and will destory an engine in short order.

 

No, it's just that the knock sensors in the LS1 are not very good. I've owned two LS1 vehicles and heard mild detonation in both of them. GM just didn't design their knock sensor very well. If they knew what they were doing, you'd never hear pinging at all, but unfortunately tons of LS1 owners do.

 

I have found BG 44K fuel additiveto be an excellent product to treat pinging and carbon build up. $20 abottle - do a Google search for a local distributor.

 

A cheaper alternative is a product called Fuel Power, it works very well at cleaning the combustion chamber, and only costs $26 for one full gallon of the stuff. You only need to add 2oz per 5 gallons in order to clean things up too.

 

Ok, so now I'm back to square one with my original question. Is a "little" pre-ignition ping, necessarily detrimental to the LS1 engine? Especially if it only occurs sporadically and only under hard acceleration or heavy lugging...like right before it backshifts?

I had mechanics tell me both things. It is bad and it is ok as long as it is not all the time.

And other than putting in an additive, which I am not crazy about doing, would the logical solution to this pinging be to retard the timing, or to richen up the fuel mixture? Or are there other alternatives?

 

The best alternative would be to get it reprogrammed and have the timing set lower. I'm planning on getting my dyno tune redone soon and this is one of the things I'll get done. If your computer is pulling back timing anyways, you're better off having less total timing to start out with so that you end up with zero knock retard instead of a lot more. So in the end you won't lose as much power.

A little bit of detonation occasionally doesn't seem to hurt the engine though, you just don't want it to happen constantly or for it to be more severe either. Best to nip it in the bud if you can. A dyno tune is less costly than a new engine.

 

A couple of questions first then I'll try to help as have others.

1st, how many miles on your car?

2nd has the inline fuel filter ever been changed?

Pinging is as some have already said is light pre-ignition. Some occasional light pre-ignition will not harm the engine. It's that heavy detonation that causes the really high temps and pressures that can cause damage within the combustion chamber.

Lean fuel conditions can cause light pre-ignition under light to moderate loads such as passing or accelerating up a hill without the transmission kicking down. Under these conditions the pre-ignition may sound like a light rattle noise from in the front of the car.

I questioned how many miles on your car for two reasons, carbon buildup and your in-line fuel filter.

The carbon build-up does slightly raise the CR, but seeing that the LS1 is 10.1:1 and the LS6 is 10.5:1 you would have to have a lot of carbon to raise the ratio as high or higher than the LS6,(for comparitive purposes). Although the LS1 engine knock sensor and spark retard program probably accounts for the different CRs, with 92-93 octane my Z06 has no pre-ignition problems so far.

I have a friend who has a 2001 coupe, he changed his fuel filter because he felt it was time to do so, since that time, his pinging has been eliminated.
So my guess is, if the filter is getting dirty there is going to be a slightly restricted fuel flow, thus causing the engine to begin running at a slightly leaned condition.

So, try changing the in-line filter, even if you don't have a lot of miles, you could have recieved some dirty fuel and the filter may be getting quite dirty and giving a reduced flow condition.

The other choice would be to have the knock sensor, and spark retard system(s) diagnosed to ensure proper sensing and retard is taking place.

On the LT1/LT4 engines the knock sensor was screwed into the side of the block, sensitivity could be increased or reduced simply by changing the amount it was tightened or loosened in the block.
The LS series engines have the knock sensor mounted in the lifter valley I believe, in fact I think there are actually two sensors up there. So it's not readily accessible to play with.

ZO6vettepilot

 

Thanks Z06vette pilot I appreciate your time.

Mine is an '04 that I bought new at the end of July and it has 4800 miles on it now. Everything is stock except for a Blackwing intake box and a Corsa Touring exhaust.

I have a Predator hand-held tuner, which I have used to back the timing off by 4 degrees, which has pretty much eliminated the pinging. And yes I am speaking of the "rattling" sound you mentioned.

I experimented with the A/F ratio by richening up the mixture and it did not have any effect on the pinging.

At 2300 rpm it indicated the total advance as being 34.9 degrees and at idle it was 13.4 degrees.

I think this problem has something to do with the practice of the refineries blending the 91 octane so that it burns a little "hotter" during winter months, therefore causing the pre-ignition problems, as I didn't have this problem until after the cool weather set in here in the Midwest.

The next road trip I take in the vette, I'm taking the Predator along with, so when I encounter a state not afraid to sell 93 octane fuel, I'm going top reset the timing back to factory specs and see if it continues to ping.

Until then, I'm simply going to leave it 4 degrees retarded from the factory setting and try to control my stop light impulses, if you know what I mean.

 

I think you have a great plan there, nothing like having the fix along to cure the problem as it happens. Let us know later how things work out for you.

ZO6vettepilot