Detonation problems

[Ferris Bueller]

I'm hunting down a pre-ignition problem and was wondering what else to check.

Symptoms:

Whenever i'm in 4th or 5th gear and I give it a lot of gas at lower RPMs, it pings slightly. The pinging goes away when I lighten up on the gas and accelerate more slowly.

Louder pinging under hard acceleration in second gear from 4000 RPMs and higher.

Pinging only occurs under these conditions when the engine is at operating temperature. No pinging under load until temp guage reaches normal range.

What I have tried:

Checked plugs: Bosch plugs seemes a little whiter than i'm used to, but not signs of damage.

Replaced fuel filter: Previous filter was on backwards

The car has 77K miles on it. Mods are in sig. Always use 93 octane gas.

 

[hioc1098]

Do you think you might be running too much timing? I'd back the timing off a little and see what happens. You may have some bad gas.

Also, check the gap on the timing adjuster. If it's too loose, it'll detonate.

Tim

 

[hioc1098]

After looking at your sig again, I don't think it's timing. I used to run 14+ with no issues. Check the gap on the timing adjuster.

If you're running Bosch Platinum 4s, I've heard of people having issues with them. Whiter plugs is a sign of the car running lean.

Tim

 

[Ferris Bueller]

Is it possible the plugs are too hot for the raised compression due to the headswap? I'm asking this since the problem seems to correspond with engine operating temperature and not outside temperature. Thanks.

 

[2002BLGT]

put in some autolite 764s and gap them at .045 , see what that does , if still pinging , drop timing back to 10 degrees

 

[Ryan L]

I didn't read all the responses, but try this first.

93 Octane
stock timing
stock COPPER plugs (TR-55s, Autolite 764s, etc)
Clean MAF sensor

That should do it. If it works, then slowly bump up timing.

 

[2002BLGT]

yea definitely clean the MAF sensor too . forgot about that .

 

[Hissmann]

What is the safest way to clean the MAF?

 

[Ferris Bueller]

I forgot to mention that i already cleaned the MAF sensor. The screen and the sensor wires were coated with a black dust. I removed the air box and screen and used a q-tip to carefully brush off the dust off the two sensor wires. I've heard that some people use electrical contact cleaner on the q-tip since it leaves no residue.

Another way to remove the MAF sensor is to undo the two torx bolts on the top of the sensors on the inlet tube. The whole assembly can them be raised out of the inlet, making the sensors easier to get to.