throttle tip in detonation

[bryan smith]

I have been having this problem for a while now and have looked everywhere. I have done a search on here and on a few other mustang boards. I have sorted through hours of posts and have still never seen anything that might help. I know Quite a few other mustangs that have mild and semi hard combinations seem to be having the same problem. I have checked the timing 10 degrees base, fuel pressure is at 45, TPS is at .78 and engine temp is at 160.
The problem is after a shift or just at throttle tip in. I get a quick bit of detonation, it disappears quickly, maybe ½ to a full second. But I know that is enough to cause some serious damage over a short time span.
Here is the part that leads me to believe it’s the ECU, for awhile the detonation went away. It was during this past winter and the thermostat got stuck in the open position, during this time the car was never went over 130 degrees, and never had even a hint of detonation.

Please help or just give me a link to some place that already has the information and I would really appreciate it.

Thanks

[gt350mustang]

need more info on the car

[bryan smith]

I have a 306 with windsor jr. cast heads, 24 pound injectors, cobra intake, b- cam, and shorty headers and a t-5 (it used to be a AOD)
Nothing to radical.

Little bit of an up date, i played with it all day today and had the base timing all the way down to 6 degrees. fuel all the way up to 45, temp all the way down to 145 and still could not reduce the detonation at all. I never got any codes out of it.

this is killing me

thanks

[Timebomb]

What year is the car? What thermostat is in the car? What EEC computer is in the car?

[bryan smith]

it's a 93 gt, thermostat is a 160, not sure which computer, stock in the 93. it was a AOD car and it was changed to a t-5 if that helps. where do you look on the computer to see which type it is.
Thanks

[XLRVIII]

Shouldn't the TPS voltage be @ or about .98-1.0 for optimum results?

Seems that the .78 on the TPS sounds awfully low..

Unless this is a "new tuning technique".

[Timebomb]

I'd try at least a 180 degree thermostat also, at 160 the car is getting warm enough for the computer to make changes. Try a 180 thermostat and set the TPS to as close to .99 as you can. Are you sure the Mass air meter is calibrated for your 24 pound injectors?

[bryan smith]

I have had in the past a 180 and TPS at .94 with the same results. I was trying with the 160 temp and low tps voltage to try and keep down the flame front and see if that helped the tip in detonation. But nothing has changed.
The mass air is calib. for 24 ponders. Does any one think it might the computer, since it was out of an AOD. Could it be that it’s not dropping the timing between shifts or tip in. When I pulled the plugs it shows I'm running rich, it just at tip in and shifts that a get the quick touch of detonation. So I’m lost, if any one could help. Please point me in the right direction. I will try anything, thanks again for every one’s help.

[XLRVIII]

I have had in the past a 180 and TPS at .94 with the same results. I was trying with the 160 temp and low tps voltage to try and keep down the flame front and see if that helped the tip in detonation. But nothing has changed.
The mass air is calib. for 24 ponders. Does any one think it might the computer, since it was out of an AOD. Could it be that it’s not dropping the timing between shifts or tip in. When I pulled the plugs it shows I'm running rich, it just at tip in and shifts that a get the quick touch of detonation. So I’m lost, if any one could help. Please point me in the right direction. I will try anything, thanks again for every one’s help.

What MAF are you using?

If the answer is C&L {as on my car} then all bets are off...

If your using another MAF, are you sure the sensor is
1. GOOD?
2. Clean?

[Blue91]

I've always heard you can use a 5spd EEC with an auto, but an auto eec with a 5spd doesn't work too well (without a chip).

I would try to borrow a buddy's A9L or A3M and see if the conditions persist. If not, you found your problem. Parts stores sell EECs (get one for a 5spd car if you get one) if you end up needing to purchase one.

[bryan smith]

I will try the EEC solution and see if that gets me any where, but something just struck me that might be part of the problem. I have a cobra intake and one of the ports is plugged, I was wondering what everyone else has done to their’s and if it needs to be hooked up and if so to what. Thanks again for every one's help

[bryan smith]

A9L or A3M out of the two which one is a better EEC. sorry again for the newb questions.

[Timebomb]

That port being plugged won't cause your problems. It's for water for the internal EGR that is built into the Cobra intake. The A9L is the most common computer that is used. Have you scanned the EEC computer for any stored codes?

[bryan smith]

Yes I have, and none came up, except the carbon canister code. Is there a difference between the A9L or A3M. If so which would be the best one for me to get. Which is the most tolerant to mods.

[Blue91]

Either will be fine. The A9L is from a 89-92 5 spd car, and the A3M is from a 93 5 spd car. I've "heard" the A3M has a higher rev limiter, but I've never verified it.

[red95gts]

That port being plugged won't cause your problems. It's for water for the internal EGR that is built into the Cobra intake. The A9L is the most common computer that is used. Have you scanned the EEC computer for any stored codes?

Actually, That's the vacuum port for the charcoal canister line. Cobra intake doesn't have water to the EGR... :)

Let the car sit overnight and check the resistance of the ECT and ACT sensors. With the motor sitting all night, the resistance of the two sensors should be very close.

[Chuck98GT]

Is your EGR system functional? If you have it blocked off or unplugged, that could promote detonation.

I do know that the AOD and 5 speed computers have a differnt slope on the acclerator pump functions, but my interpertaion of them is that the AOD would acctually pump more gas releative to the Throttle position.