Detonation, AGAIN?!?!

[95mustanggt]

Dam car! Now that it is getting a little warmer my car is starting to detonate again. I can't do it now, but I'm going to have to start checking more things.

I've already either checked or replaced the MAF, IAT, TPS, and Coolant temp sensors.

What are some of the mechanical things I could check. I've been thinking of the following

1. Air passage between MAF and intake
2. Injector screens
3. timing chain
4. Carbon deposits on the heads
5. EGR valve
6. fuel pump

Can you guys think of anything else? Also if you know of a good test for the above that is quick and easy let me know.

Thanks.

[COLT5O]

What is your timing set at?? Is your MAF sensor filament dirty?

[95mustanggt]

Timing is at 10 degrees, but I have a Super Chip. The problem seemed to be unrelated to the chip, as it occurs even when it is removed. I run 93 octane Mobil gas.

My MAF is only like 4 months old. I have not looked at the element, but I would guess that it is ok.

I'm thinking either I'm running short on fuel or air is coming in some where.

Something that is odd, is that the oil level seems to drop real fast some times. I do have a small leak in the rear seal (nothing major), but I always thought it was wierd.

[COLT5O]

Check your fuel pressure, my stock pump was weak and caused me some problems before the supercharger.

[Shogun]

When was the last time you checked your plugs? I hope you don't use platinum plugs, which in my humble opinion, retain way to much heat by having two or more grounding tips on them in addtion to prolonged ceramic electrodes, also generally being catagorized to high in the standard plug heat ranges. They were designed for highway use and extra long life. Not suitable conditions for most modified Mustangs. Autolite 3924 is all you need for plugs. unless you have a power adder of some sort, then you might want to step down to a colder plug. Also, are you sure your timing is set to 10? I am by no means trying to insult your intellect, but I have had a few people with the same problem only to find out that they indeed checked the timimg, however forgot to pull out or replace the "SPOUT" connector by accident. Just an idea. I hope it helps.

[gtsr515]

Do you run a 160 thermostat?, that usually causes this in conjunction with the chip present or removed, also make sure spout is removed before checking timing, also, is the gas consistant with what you usually use?

Also, check your air filter for cleanlyness and make sure it is sealed tight.

[Shogun]

Originally posted by gtsr515
Do you run a 160 thermostat?, that usually causes this in conjunction with the chip present or removed, also make sure spout is removed before checking timing, also, is the gas consistant with what you usually use?

Also, check your air filter for cleanlyness and make sure it is sealed tight.

What? I am not sure at what your trying to convey. Are you suggesting that his use of a chip (or not) to include a 160 degree thermostat are the root of his problem?

[95mustanggt]

Thanks for the replies guys.

Well it's pretty cold here in Dallas so I've had no problems the last couple days. I set the timing back to around 8 degrees. Don't worry I remove the spout when I do the timing.

When I got the chip I believe I was suppose to run a 160 thermostat (I got the chip used from a very good source ). Anyway the car is having trouble staying (and getting to) the Normal mark on the temp gauge. I'm still running the stock thermostat, so I think I'll change it. However I would associate detonation with heat not being too cold.

My plugs are standard Ford replacement plugs, gapped at .052.

I've been wondering about the fuel pump too. COLT5O, did your car ever have trouble starting sometimes? Sometimes when I turn the car over, it just turns, without starting. I turn the key off then on and she starts right away. I think that the fuel pump is not priming when I turn the key.

I'll check the Fuel pressure, good tip.

[COLT5O]

My car was never really hard to start it just seemed the crank time was longer than it should be. The new fuel pump seems to have eliminated the longer crank time.

[LX XLR8R]

you say you are loosing oil..is there oil in you intake??your PVC could be fucked and you can be sucking in oil and when you have oil in your combustion chamber you are actaully increasing your compression @combusition cuz the oil does not compress like air does..something to think about

[95mustanggt]

LX XLR8R,

When I checked my plugs a few months ago, they did look a little oily. The crankcase breather tube from my oil fill cap to the intake tubing is a little oily as well.

Time to check the PVC.

[PKRWUD]

Originally posted by 95mustanggt
What are some of the mechanical things I could check. I've been thinking of the following

4. Carbon deposits on the heads
5. EGR valve
6. fuel pump

Also if you know of a good test for the above that is quick and easy let me know.

Thanks.

Carbon deposits on the pistons would contribute to pinging, but it shouldn't be temp related.

An EGR valve that remains open during WOT would cause pinging. Next time the pinging starts, disconnect and plug the vacuum hose at the EGR valve. Start it and see if it idles okay. If it does, the valve is closed. Drive it hard and see if the pinging reoccurs. if it doesn't, there's a problem with your EGR, and it needs to be diagnosed further. If it does, reconnect the EGR, and check the fuel pressure.

You need an EFI fuel pressure gauge. You need to check several things, including pressure with and without vacuum applied to the regulator, with the engine off and running. After it's run a while, and the pressure has stabilized, shut off the engine and watch the gauge. It shouldn't change (bleed down) at all for at least 1 minute. If it does, you either have a regulator problem (unlikely), leaky injectors (unlikely), or a bad hose going to the pump in the tank (likely).

Any codes (KOEO & KOER)?

Post the results from the above tests, and we'll go from there.

Also, just to rule it out, the next time this happens, you can try removing the chip, making sure the base timing is at 10 BTDC, resetting the ECM, and seeing if that takes care of it. Chips do go bad. I just had one fail after 2+ great years.

BTW, with a chip installed, you need to run the recommended t-stat (usually a 160), use only 92 octane or higher fuel, and leave the timing set at 10 BTDC (with the spout removed).

Take care,
-Chris

[95mustanggt]

Thanks PKRWUD, I'll give it a try hopefully this weekend. I just need to get a fuel pressure gauge.

Detonatoin was the same whether the chip was in or out. In fact the car idles better with the chip in. I'll check the egr and the fuel as recommended and go from there.

Oh and my PCM shows no faults last time I checked.