The timing on my motor is just fine... <img src="/forums/images/graemlins/rodent.gif" alt="" /> Its was yours I was worried about.

Might want to check a few other things as well... Not just the base timing. Combustion chamber deposits or a bad injector can cause problems as well.


Kevin

That engine has a detonation sensor, and constant runs the timing up against spark knock, then backs it off, the advances until it hears knock again, then retards it again. It should retard the spark every time it hears knock. You can sort of test it with the starion knock box test. Using a timing light and a mark on the crank sprocket for reference, sharply tap a bolt on the valve cover with a steel hammer to simulate knock, and watch for timing retard with the light.

Ditto Kevin on the combustion chamber deposits, which can glow white hot and prematurely ignite the fuel, as well as a partially clogged injector that leans out the cylinder and heats up the metal inside to ignition temps.

Combustion chamber/valve deposits and sticky injectors are certainly likely culprits.

Other possibilities include a bad knock sensor, bad ECU, engine overheating due to a degraded cooling system, clogged fuel filter, dying fuel pump, bad o2 sensor, wrong heat range spark plugs and an inoperative EGR system.

I'd start with some fuel additive to try to clean the injectors.... might help, might not.

Frank

Frank,

Good point on fuel delivery. Most times my turbo 2.6 with a detonations sensor adapts to fuel conditions very well, dropping the boost back when needed. The one time it leaned out because I was going up a hill and out of gas , instant detonation. The system was not able to compensate for running lean.

Kevin

Doesn't it retard the ignition lead rather than reduce boost?

Frank

It does drop the timing back, but that's something that's hard to notice from the drivers seat. I can see when it drops the boost back on the pressure gauge.



Kevin

I didn't know that could be done. How does it drop back on boost? Open the BOV? I thought that was a pure pressure setting, but I don't know so much about turbo stuff.

Frank

My system has a two staged waste gate. The ecu / spark computer controls a valve that sends boost to one chamber or both. With both pressurized, the boost drops by about 3-4 psi. There are more complex systems out there.

Kevin

Ahhh - now I understand. My blower is not so sophisticated...... <img src="/forums/images/graemlins/lol.gif" alt="" />

All I can do is pull ignition lead.... in the look-up table for rpm/kPa and with the knock sensor circuit on knock detection.

Frank