REALLY the Knock Sensor or is it the ECM?

[scd88ga]

Well it turns out it really IS the ECM. Or has to be anyway......

Pulled the ECM and guess what? It appears FINE. No corrosion on the pins or wire harness plugs at ALL anywhere. They were all in PERFECT condition.

I couldn't see any burnt spots on the ECM or chips or what have you. The coating seems perfectly intact on the board. I sprayed the ECM , E-PROM connector and cover out while dis-assembled just cause anyhow. Reassembled and put it back in. Same story.

Thought so! And free of visual damage just as I stated mine was! Go figure eh!!! It makes you wonder how many Beretta's have been junked for the very same reason!!!!! It also makes you wonder how many thousands of time this had been misdiagnosed over the years causing people to throw countless hundreds of dollars into the wrong parts! YIKES!

I'm glad you got it figured out though, stupid ECM's...

[SuzukiGhostRider]

Well, I was wrong...again. This bitch is really pissing me off. She's ALWAYS gotta fight tooth and friggin' nail against me. I mean, seriously....wtf? I've dumped THOUSANDS into this car and it's fought me every inch of the fucking way... /Rant

Ok, now that I got that off my chest.....

Put a new (fresh reman ,right outta the box) ECM into the car today. New knock sensor was still on the motor as well. Fired it up, waited.

About 2 1/2 minutes later.... CEL....

ONLY code 43 this time. No 66 anymore.... So, I'm thinking ok, a few possiblities here. ECM was bad AND the E-PROM or ECM was bad and new KS is defective.

So, for shits, giggles and grins, I put the "old" ECM back in , fired it up. After a minute or so.... Code 43, NO MORE code 66 anymore on this ECM either..... Hmmm... So, now I'm almost sure the new KS is defective...

I swap the old KS in, and bam. Same code on both ECM's. 43, and no 66 in sight.

So, I guess now we know the only answer left besides me tracing wires, is a faulty chip. Seeing as the EST circuit resides on the chip and that's the ONLY code I'm throwing now....

So, I have 3 chips en route. Big thanks to a member of Q4F for that! Why 3 you ask? Two reasons.

1. In case one (or more) of the three is also defective.

2. I have two '92 Quad 4's. The SCX and GTZ. They use the same ECM. Nothing like having a "just in case" spare or two around!

So, I will update this thread when I receive my "new" chips.

[3X00-Modified]

Why don't you just unplug the knock sensor and see what happens... if the code still gets thrown then its the wiring. These cars or at least my OBDI and II car would run with the sensor unplugged and not throw a code. I used to do that with the Pink car before I insulated it from the headers... it would pull obnoxious amounts of timing at part throttle from header noise so I had to remove it for my drive to Chicago. I plugged it in for the runs at the strip though.

[scd88ga]

I have access to the correct E-prom. Thanks for the offer though.

I wasn't offering E-proms. If you have access to the correct E-prom, then put it in! Like I said, I changed my ECM and E-prom at the same time with a matching used one, so I don't know which of the 2 parts were causing the problem. More than likely it was the E-prom though.

[SuzukiGhostRider]

Jon,

I don't think that will work as , from my understanding, the circuit for the EST is located ON the E-PROM. Then's there's the fact that I don't want to risk detonation from no proper timing advance/retard due to no KS signal.

Plus , I'm not sure that it throwing a code with the KS uplugged is definitive proof of a wiring problem. A bad chip would also do that.

Brett,

I am waiting for the E-PROM's to arrive and then, that's EXACTLY what I intend to do!

[ronaconda]

I would have to agree with Jon on this one Mike...from my experience with what happened to me, and my code 43 experience is its either the KS or the ECM and the specific circuit, but not the PROM. Correct me if i'm wrong, which i know you will, but the PROM simply is a memory chip that has values stored on it...its the ECM that actually interprets the input from the sensors and throws the codes if the inputs are out of specified ranges, aka stored values on the PROM.

[3400beretta]

Jon, not sure what you are thinking about there but unplugging the KS will throw a code within about 10 seconds (on a v6 or a quad). On the quad 4 there is an internal resistance of 90k-100k ohms in the knock sensor which the ECM is looking for at all times. If the ECM sees anything else, including an open or a short to ground, it will set a code.

SGR: Unplug the blue ECM connector and check resistance between pin BC13 and ground. It should be between 90K and 100K ohms. This will tell you if your wiring and grounds and KS are okay or not.

If you do get that value, then its definately the PROM, but I have yet to see one of those go bad.

EDIT: Jon, I just checked my '96 manual and the computer handles a KS circuit malfunction a little differently than OBD1 does. On OBD2 if you unplug it, it looks like it won't illuminate the MIL, but it does still set a code.

[SuzukiGhostRider]

Ron:

I've got TWO different ECM's (one brand new basically) telling me the SAME code, AFTER a leak was detected in the ECM storage area from three days rain. I somehow doubt my KS or wiring went bad sitting doing NOTHING for a week.

If the E-PROM was indeed damaged (which I'm almost sure of at this point) then ,if nothing else, it could be giving false "values" to the ECM when read. The circuit range is stored on the E-PROM which is what I was referring to.

Rodney:

Thanks, will do that circuit check as well.

[scd88ga]

Brett,

I am waiting for the E-PROM's to arrive and then, that's EXACTLY what I intend to do!

The suspense is killing me! lol

[SuzukiGhostRider]

Actually, me too. Really....

Bitch better get some act right going this time.... I'm tired of her little fits everytime I drive another car for a week..... Jealousy.....

[3X00-Modified]

I drove to Chicago with my knock sensor unplugged... never got a code present or SES... It's not what I was "thinking" its what I've "experienced"

Also there are two parts of the knock sensor here... One is physically on the ECM for me a raised chip, for you its the second half of the prom, I was not referring to removing that part, I'm talking about physically unplugging the sensor on the block.

[SuzukiGhostRider]

Little update. We got some snow mixed with rain this morning early. So , me being the gungho type, I went out in it to see if I could spot my EXACT spot of leakage in the Z. Pulled the glove box and under cover and looked up in there. It's DEFINITELY the fresh air vent seal. It's leaking on the lower left corner and dripping down beside the airbag module. However, the water appears to go nowhere NEAR the ECM. But, that said, the rain and snow we had today was NOTHING next to the three days of constant heavy rain that brought this matter to my attention. That was like Noah's 40 days and nights type of rain!

One other thing I'd like to mention and I'm curious about. I keep seeing people saying the "ECM is directly under the fresh air vent". NO, it's not. Not even close. It's about 6" or better to the passenger side up against the passenger side of the body directly above the kick panel speaker. At least in my '92. Is it located differently in '96? Or '95? I didn't think it was , but I could be wrong.

Anyhow, I figure when we got the "noah's ark rain" it was enough water leaking in that it found a way to run over by the ECM and was just enough to short something or get something wet.

Hoping I can still find the fresh air vent gasket anywhere. If not,sealant will work. It's actually called for in conjunction WITH the seal according to the FSM.

Still waiting on my "new" e-prom chips. Seller shipped Monday so hoping to see them in the mailbox today!

[3X00-Modified]

Might be time to also do a ohm test on the knock sensor circuit.

[SuzukiGhostRider]

KS circuit test was done long ago and it's fine.

So, final result. It was the E-PROM as I suspected. I installed my "new" used chip in the ECM and everything is gravy thus far.

Thanks for all help and suggestions. In the end I guess, I was already pretty sure of the solution anyhow, but it's always helpful to get some outside input sometimes.

The only reason I waited until today was I was battling a fresh air leak it appears I also finally conquered! Yay me!

[scd88ga]

Flawless Victory!