pre-ignition ??

[prozacposterboy]

Okay... here is my problem.

I replaced the timing belt and adjusted the valves. It took me 6 times to get the valves right, but i did it. Here is my problem:

I am having problems with pre-ignition. I tried adjusting my valves thinking that was the problem but realized (about attempt 3 or 4 on the valves) that the noise iheard was preignition. So a break out the handy dandy timing light to check things and my timing is off by only a degree or so. I adjust it, and my pre-ignition noise is even worse. The only way i can eliminate the noise is to retard the timing...right now, its about as retarded as droolin' Johnny riding the small bus. My problem is that i have an emissions test on saturday to make.

Anyone clue me in to this?

my first attempt at the timing belt change resulted in my timing being a tooth or two off (couldnt even find the marks to set ignition timing) so I set it back to the dealer specs (thanks again Paul) and now im having this preignition problem.

My distributor w/vaccume advance was changed about 10,000 miles ago.. is it possible that it could be defective? I have pinging with both the vaccume lines connected to the distributor and disconnected and plugged.


Im really stumped and im reluctant to screw with the timing belt again if i dont have to... thats why im asking first. I may rip off and exchange my distributor simply because it has a lifetime waranty and it'd eliminate one of my theorys.

Thanks in advance for any help.

P.

[A20A1]

I doubt it's the advance since a broken diapragm would give you no advance... anyways look on the cam gear and on the flywheel, check to see that they both are at TDC...

[prozacposterboy]

they were both set at TDC when i set the timing belt... would it being one tooth off cause this advance problem?

[MoonScryer]

I had to set mine a tooth back to get rid of the pinging, even with the belt at TDC...my cam gear was brought a little forward to compensate, and now I got this great powerband. I doubt I would pass a NOx test though; glad we don't have them here...

[prozacposterboy]

hmm.. I gotta figure it out soon or ill have to cancel my smog check... I exchaanged my distributor to eliminate a possability...

anyone with any ideas?

[joebeets]

Put in some premium gas and go get smogged :)

But it's probably the EGR system, designed to lower burn temperature to inhibit the formation of oxides of nitrogen (NOx). It allows manufacturers to program more agressive timing advance curves without detonation on lower octane fuels, ESPECIALLY at lighter loads where EGR has its greatest effect. Take away the cooling effect of the inert (non-combustable exhaust) gas in the cylinder without changing the advance curve (only an option with mechanical distributors) and you have exactly the problem you describe.

[prozacposterboy]

Well i fixed the pre ignition ping... it was the vacume advance on the distributor...