Pinging @ 12* base timing, 93

[jabGT]

My car pings @ 12* base timing when N/A, running 93 octane. Trying to hunt down this detonation problem before S/C goes back on and start tuning. Anybody else have this problem, is it more common on 94-95 then foxes? Talked to a few places and they seem to think it is a engine problem (carbon build up/hot spots). Had heads off awhile back and clean the pistons everthing looked really clean.

thanks for the help

 

[matt_656]

try pulling the timing change pill-plug and driving with no computer advance, it won't have any power but i think it may be a computer advance problem.

just a guess, hope it helps.

 

[matt_656]

that will at least give you somewhere to start.

 

[jabGT]

Yeah, I lock my timing out at 20* I run that when the supercharger was on, and no detonation. However my car should not be pinging with 12* base normally aspirated with 93 octane (or at least thats what I've been told).

 

[blksn955.o]

is your smog hooked up?

Things can get worse if you have the EGR unhooked and still turned on in the eec. The eec will think there is more fuel (with the EGR gasses) and it actually adds timing, so you are at a higher risk of ping/det. if its still on in the eec and the EGR is not hooked up.

Other than that and your looking at stuff like oil blow by (oil in the chamber can cause det./ping) from worn rings and some other stuff.

 

[jabGT]

EGR is still hooked up, smog pump deleted (not that it has an effect). I don't have blow-by to my acknowledgement & I get 145-150 psi from all cylinders.

 

[HISSIN50]

Yep, more common on SN's than foxes. Foxes tend to run rich when sensors go south and SN's seem to go lean when they do.

If you have not already, I would take a look and clean the MAF and IAT. Ditto for the ECT if those two dont help. Pinging on 93 at 12* aint right.

Good luck.

 

[matt_656]

another thought is a stretched timing chain... but i think they are on the right track with the bad sensor thing.

 

[BlownFiveLiter]

Heck, I'm at 14 degrees, and I can get away with 89 octane and no pinging (N/A). Are you running the stock balancer yet? It could've spun a little, causing your timing to show more than it actually is.

 

[mo_dingo]

Start w/ cleaning your MAF/IAT sensors, and doing a complete tune up....

You may be in the boat i was....I had to scrape the 1mm thick layer of carbon off of my pistons and replace my heads...that sure got rid of it....
Scott

 

[jabGT]

I put a new balancer on early this summer (pioneer heavy duty), so will make sure the timing marks are correct just got to find a piston stop. What is the life limit on the timing chain I've 80,000 miles on the car? I will also clean/replace the sensors. I had the heads off recently and the piston didn't look to have too much carbon, I cleaned them anyways. Do you think a bad valve job (too thin of a valve margin) would cause detonaton? Fried the valves once and the shop reground the seats twice because they leaked so bad, finally ended up lapping them myself.

Thanks for the help guys.

 

[BlownFiveLiter]

If you have an aftermarket balancer, I'd look elsewhere for the issue. I'm sure that one is perfectly fine, and definitely better than stock. As you know, it can only go on one way, so... what next?

 

[jabGT]

Yeah, I know my balancer is good by means that it hasn't "spun". I just want to make sure the timing marks are correct, you never know it was cheap