Spark Knock From Fowled Plugs?

[burn]

Hey everone. Ive been reading on here for quite some time, but havent really posted much on here. Just to get everyone that dosent know me up to speed, I have a 92 cavalier sedan, with an ECM & trans from a 91 Z24, and an 03 3400 from a Buick Rendezvous. I was running the stock PROM & 3.1L injectors but decided I wanted more by going to the OEM 3400 multi-tec2 injectors. Ive ben custom tuning my own chip to run the larger injectors. So far the chip runs very well, and other running my chip are loving it. However, during my tuning Ive obviously beaten the crap out of my plugs. They have been excessevely rich & lean countless times. I think I finally found a happy-medium, but im still getting spark knock at 5600RPM regardless of how much fuel im dumping in. Mick over on GMPCM suspects I have an ignition problem. My ICM / coils / wires are like new. The stock 3400 iridium plugs have taken a beating though. Think a bad spark caused by the condition of these plugs could be my knock culprit?

Thanks guys

[sil]

those look really really really lean

[geoffinbc]

Yea they have been running lean or sure. But they do not appear to be melted or distorted. They should be fine.

Fuel and Timing and things to go after. How much advance are you running?

[burn]

im running the stock 91 3.1L timing on th ARUR program.
I have my ignition relocated... im wondering if that not contributing to the problem. Im gonna move the ignition back so I can use the plug wires that ame with my 3400, there practically new anyways. lol
its running pig-rich, and I keep dumping more fuel in to get rid of the knock, but around 5600RPM it keeps coming back. Its weird cuz at that RPM my O2 is reading over .9V, my BLM & INT are both less than 128... its not like its leaning out.
last night I replaced the plugs with just ACDelco plugs gapped to .035. I had WAY more knock, but i believe thats because I have a stronger spark.

[sil]

have you tried a 1-step colder plug

visual inspection of the plug, are there micro scopic metal specs on the electrode and insulator?
any yellowing of the insulator(hi speed glaze)
just a hunch but id say try 1 step colder plug :P

or back off the spark in yoru problem area, sometimes adding fuel just doesnt help (so i hear)

could even be a sensative, near faulty but working knock sensor.. just a guess
or screwed in too tight

take it out and use teflon on the threads then put it back in, but not so tight

just some things for you to try

[burn]

when i originally installed my knock, i used teflon and that was a big no-no... the teflon works as a bufer and can interfere with the knock detection.

the plugs are basically clean, other than the white from the lean conditions.

im already running 2 steps colder plugs, and the knock got worse than with the stock plugs.

right now im working through testing that my coils & wires are good.

[rx191]

the engine is leaning out and causeing a lean mis thats why the o2 sensor is reading rich, anytime you have a lean mis you will get unburnded gas out the tail pipe, the mis may be so small that you don't ever feel it but you can here the knock from the mis, raise the fuel pressure, that will help at high rpm and when WOT but you will need larger injectors to get rid of it at part throttle. does the knock happen all the time or just at certain rpm or throttle, let me know i can hel pyou alot with this one

[burn]

the engine is leaning out and causeing a lean mis thats why the o2 sensor is reading rich, anytime you have a lean mis you will get unburnded gas out the tail pipe, the mis may be so small that you don't ever feel it but you can here the knock from the mis, raise the fuel pressure, that will help at high rpm and when WOT but you will need larger injectors to get rid of it at part throttle. does the knock happen all the time or just at certain rpm or throttle, let me know i can hel pyou alot with this one

im actually running the 3400 stock multec2 injectors, and I am custom tuning my own chip. I have it running pig-rich in the power-band but it keeps knocking.... and now that GMPCM is no-more Im having a helluva time get support with it now.

[SHOoff]

Is it a knocking that you can hear, or is it possible that the ECU is just picking up a knock for some reason unknown?

The Circle, Slash on the GMPCM I can see being a big problem though. That's the reason I've decided to swap to a Megasquirt ECU.

[burn]

Is it a knocking that you can hear, or is it possible that the ECU is just picking up a knock for some reason unknown?

The Circle, Slash on the GMPCM I can see being a big problem though. That's the reason I've decided to swap to a Megasquirt ECU.

cant hear it... it only registers on freescan... and it only does it in 1st gear between 5500 & 6000 RPM.

[SHOoff]

I'd almost guess that it's not really there. 3800 S/C GTP's get a false knock coming from the tranny. Since it's only in 1st gear of a span of 500 rpm, i'd guess that the KS is probably hearing something else.

[burn]

I'd almost guess that it's not really there. 3800 S/C GTP's get a false knock coming from the tranny. Since it's only in 1st gear of a span of 500 rpm, i'd guess that the KS is probably hearing something else.

thats sort of the feeling I get also... Its just annoying cuz I can feel the car pulling like crazy, then all of a sudden it falls flat on its face it 5500 cuz its retarding the timing When my trans is cold it makes an whole orchestra of noise. LOL. probly cuz I beat the piss out of it, but it runs like a champ and shifts like butter.

I might swap to the GM synchro mesh fluid, I just have regular Dexron IIe ATF in there now, my manual says its OK to use, but ppl keep saying I should switch to synchromesh... might be my problem.....

[Dave]

you could try a couple different things...

since you're able to burn your own chips, you could try pulling the knock sensor function and give 'er a romp like that (just one tho, so you don't kill anything)

or 2 - I've heard of people putting a bunch of dynamat (or some other sound dampening material) on the trans case to help hide the noise that leads to the false knock.

good luck!

--Dave.

[sprucegagt]

This is a thread back from the dead.

Any update on it?

I take it your running 50 PSI fuel pressure at WOT. MULTEC II injectors run at a higher pressure than the old Bosch style injector.

[burn]

im running the multec2 injectors with the stock 00+ FPR. I wont have any updates until spring since its off the road for the winter.