88GMC1500

I have the 7060 in a vehicle Im working on. When you go WOT up a hill, I get a quick "knocking" or pinging of the valves for a split second, then its smooth as silk. I just rebuilt the upper end of the motoer, new cam, valvles springs, etc so its not a mechanical issue. I have set my timing to 0 with the ETC disconnected, replaced the distributor pickup coil, ingintion module on the distributor, cap, rotor wires, coil. NOTHING is helping. After I hear that knock for a split second, I get a CEL and then I never hear the knock/ping again during that run till I shut it off for a while and go for another ride

Any ideas? This is a stock ECM that I have not burned yet. I would love to be able to swap it out with one of my 7747 ECM's I have laying around but its not a simple swap as harness changes are necessary due ot the 4L80E trans.

Also, I am unable to get an ALDL stream like i can with my 7747. I have tried winaldl and tunerpro RT but it looks like they dont like this ECM.

88GMC1500

bump...

I dont use the truck much which is why its been so long but the problem has become worse. I dont get an SES light anylonger but the knocking is intense and until I let off the pedal and accelerate again, it will persist. How can I test the knock sensor? Does anyone know what the ESC looks like or where it is? The truck is a 91. On my 88 pickup, the ESC is flat and square and bolts up on the intake manifold but that component is missing on this truck.

Six_Shooter

iTrader: (2)

The knock filter, is built into the ECM, it is part of the MEMCAL in the '7060.

DENN_SHAH

iTrader: (1)

at Moates filemanager look under "4) Datastream Definitions" and then look for 16147060_4L80E_A138_A177.ads and see if it works for you.

if you do want to swap the ECM, i believe there is a How To either here or at FSC on swapping in the 16197427 ECM.
IIRC, there are only a few pins that need to be moved.

Keith91sub

What are the benefits of the 16197427 over the 16147060?

va454ss

iTrader: (1)

Have you checked the EGR valve?

88GMC1500

I disconnected and plugged the vacuum on the EGR and there was no change. Is that not a sufficient check?

va454ss

iTrader: (1)

What T stat are you using?

88GMC1500

stock - 195 F

88GMC1500

So I found out that in 1991 the introduction of the 16147060 on my truck includes a different knock sensor. The part number for the one I'm using in the truck and having issues with is SU154 (from autozone WELLS brand I believe). Turns out in previous years that was correct but in 1991 that sensor is listed only for the Manual transmission option and the automatic lists an SU169. I just picked up the SU169 and got on it with a meter. At rest it shows 3.91K Ohms. If I tap it with a hammer, I see it jump as high as 8 or 9 K Ohms

Does anyone know what the difference betwen the SU154 and the SU169 is besides a white top versus a black top?

When I get a chance to install this, I'll post back if it fixes the problem or not

88GMC1500

I finally got around to replacing the knock sensor and the problem is resolved. The truck has much more power now and gets 1.6 MPG better than before. I cant believe this has been the problem for close to a year and i was just now able to figure it out.

Thanks for all the help guys!