Detonation?

[z9_87]

I have a new little gremlin that poped it's head up recently.

When under high-load low rpm acceleration or durring deceleration from higher speeds(55+) it seams like I get detonation. It makes a usual noise of detonation and tries to go but just sits there and sputters if I hold it there. If I step on it while its sputtering, it intstantly goes away.

So detonation check list that I can think of:
timing - 10*
fuel - 90
compression is around stock for a 89-93
lean mixture maybe? - it's 19lb injectors no egr.

I don't know beyond that anyone have some suggesitons?

 

[HISSIN50]

Zach, is this mostly while in OD?

Also, if you happen to know (I'm not familiar with the changes for 'Birds), is the puter RPM or load based? Electronic or mechanical trans (I assume RPM based and mech trans, but wanted to ask).

Good luck.

 

[z9_87]

Actually the OD went out on my tranny, thats another problem but i know what to do with that. The tranny is an AOD just like in the foxes and the computer is an 89 stang mass-air.
It pretty much never happens in 1st cause of the higher rpm's. But 2nd and 3rd when low rpm accelrating it happens a lot.

 

[Roland69]

my truck makes the same type of noise and it is just a very small exhaust leak. It makes the noise only under load accelrating but goes away when there isn't much of a load.

 

[Roland69]

for right now you could just try some higher octane. It may be carbon buildup on the top of your pistons giving you higher compression. wouldn't hurt to try running a can of seafoam through a vac line but try some higher octane first.

 

[86bluecobra]

i was going to say it could be carbon build up. they cause hot spots which ignites the air fuel mixture prematurly. need to clean up the combustion area.

 

[Hickfied]

You don't have the EGR system hooked up do you? I think that is your problem right there, though I could be wrong.

 

[z9_87]

No I don't have the egr, and I was wondering about that. I have already tried some 93 for a tank.
I'll run a can of seafoam through just to see if that does anything.
And the header bolts wiggle loose every now and then so I guess I can take awrench to them, but I know there's no rust or anything like that on em.

Thanks for the replies.

 

[vristang]

If the egr is tha cause then you will need to reinstall the egr or disable the function of the egr in the computer.

Mine pinged pretty bad until I started playing with the tweecer. Now my ping is all but gone.

jason