heat causing detonation?

[94_Maroon_GT]

I have been having some problems recently with my car detonating when it gets warmed up. I have had to set the timing back to 8* just to drive it. When the engine is cold the car runs great but once it gets up to normal temp it will ping at about 3000-3500 rpms. What could be some things I could check? Spark? My coil termial is corroded. Plugs? I have crappy platinum plugs. Fuel? I got a new fuel pump (255 lph) but could it be the regulator? What about O2 sensors? I don't know where to start and being in college doesn't give me a lot of money to replace everything to find the problem. BTW the car has 167,000 on it. Thanks in advance guys

Andrew

 

[black945.0]

with all the miles u have it could be carbon deposits on the piston causeing higher compression i would run the car low on fuel and fill up with a higher grade fuel the higher grade of fuel u use the less volitle it is that is y they have to run higher octane in high compression engines i would try there cause that is also the time the egr is opening up putting hot exhaust gas as well taking up more room the best way to get rid of carbon deposits is to pull heads and have them cleaned try to set the timing at 0 advanced timing lights off too soon and with a higher compression it makes it easier to light

 

[94_Maroon_GT]

Right now I use 93 Octane. Do you thing the SeaFoam stuff would work as effectively as pulling the heads. I really don't want to pull them just to clean the pistons. Unless I had some AFR 165's

 

[black945.0]

i havent herd much about it its worth a shot i would only pull the heads as a last resort ask around here to c if anyone else has an idea on getting rid of carbon build up

 

[Zero Signal]

There are a bunch of things that can do it.

Dirty MAF (reading too low) - most common, most likely problem
Bad ECT ( bad harness, old thermistor)
Bad ACT (bad harness, old thermistor)
Hot spark plugs (platinums) - definitly a problem with your case
low octane
overheating (bad fan, bad ECT)
bad fuel pump (bucking, low power, low fuel pressure, no hold pressure)
bad regulator (no hold pressure, low fuel pressure, low vacuum)

Carbon buildup isn't really a problem with our cars since they run so lean, but it never hurts to do that Seafoam treatment.

- First clean your MAF with some alcohol.
- Clean your filter or get a new one while you're at it.
- Buy some Autolite 24's or 25's.
- Clean the ACT sensor, it won't do much but why not.
- Check the wiring around your ECT sensor if your are running hot.

- If neither of these helps, rent or buy a fuel pressure guage and a Chilton's manual to test the fuel system.

I only list these things becuase I've had ALL those problems and I fixed ALL of them. In the end, the only way I found to truely fix the problem was a tune. The flaw with our cars is our computer. With all the smog junk and changes from A9L, I think somehow, they fudged the tune or the MAF in the process. I was able to fix the problem by changing the MAF curve over 3000 rpm. The car just ran super lean. I richened it up, it ran awsome and cooler. I then was able to put alot of timing into it.

 

[black945.0]

if u know any one with a shop run it on the emissions machine and see what kind of gas reading u get i jsut got my emissions license i so i might be able to help u out better

 

[slvrsn95]

oh the 94-95 detonation thing, 9 times outta 10 its going to be dirty electrodes in your mass-air meter and with the miles that you have if that thing is stock and never been off of the car then it's possible that may be your problem but detonation will usually happen under heavy load and you say your getting only from 3000-3500. Go to sears and get the torx.bit you need to take it apart and clean the electrodes and see if that does it.

 

[94_Maroon_GT]

Thanks so much for all the advice. I had tried to clean the maf in the past by spraying brake cleaner into it. I never tried taking it apart but it will get done this time. I will post when I finally get it fixed.

Andrew