I am finally going to spend some time working on Zannah (my 92 6 speed vert). About a month ago I data logged and discovered she has severe knock retard. She pulls 9-14 degrees before 3500 rpm. I searched and read a bunch on here. I came across a thread where someone pointed out different KS between 84-88 and 89-91. One is 100k ohms the other is 4k ohms. I have the FSM and can't find any specs on the 92 KS ohm rating. I found, after an exhaustive search the FSM leads you on, the section on the KS. It simply states to test them at 1.5 v indicating no KR and then to tap on the exhaust and see if KR is detected using the scan tool. I don't have a scan tool, but I do have a data log program on my laptop. It will be difficult to read this and do the test. Does anyone know the ohm rating for the 92 KS? Also I'm going to hunt for the wires that go to the KS. Any tips on where they go from under the car? I already looked under there and it looks like mine were cut and reattached as there is electrical tape. So the hunting begins.

 

Does your FSM not have a pin out of the connectors that go to the ECM??? This is for a 1990 but should be similar Knock sensor wire under the engine should be DK BLU and goes directly to the ECM unless your car has a ESC module. I'm not sure what GM did between years and what got what. i.e. ESCM equipped, OBD1, OBD2

 

The 92 has a quite a bit more. On the bottom of that page for your 90 it shows ECM Terminal Connector View "Y" Carline (2 of 2). Around the same pages for the 92 it shows up to (7 of 7) for the ECM "Y" Carline. The ASR throws in a lot more connectors. One of the wires even show ASR Timing Retard Signal. I don't think that's my problem since it does this issue with or without the ASR engaged and pulls timing even when I'm making a simple low speed 3 point turn.
Everything is hooked up on mine and I even replaced the KS. I'm just curious if they're cheap wrong ohm specs or something. It does look like the ends were replaced as it is common for those to break. I might replace them again since I have no idea how long ago they were replaced. They may not be getting a good signal. My car was very oily and dirty before I changed the pan gasket and the KS that were on there.

 

Has the car been sitting (old gasoline)? Any mods to the car? Any event that MAY have caused the issue? I assume it's down in power when driving it? Above 3.5k rpms, how is it?

 

I bought her in October 2021. I flew into Reno, NV and drove her 500 miles home to Simi Valley, CA. I didn't push her on that drive, but she cruised at 75-80 effortlessly. I got about 26-27 mpg on that drive and used 2 tanks of gas that night alone. I have driven her a decent amount since I got her, but not a daily driver. I always use premium and have even ran SeaFoam in her. She is pretty close to stock. She has a Flowmaster exhaust. I recently upgraded the injectors to Bosch IIIs. She has done this issue since I got her. I also replaced the timing chain, lifters, oil pan, valve cover and intake gaskets, KS, o2 sensors, a few oil changes, oil pressure sensor, water temp sensor, plugs, wires, belt, pullies, and who knows what else. Right at 3500 RPM she feels like a turbo is kicking in and gets a boost of power. She idles smooth, has decent power down low, but has that turbo boost above 3500 RPM. Nothing I have done has helped it. I bought the tuning software/hardware a couple of months ago. Finally data logged her a month ago and confirmed the reason why she has the turbo issue or lack of power below 3500 rpm as the pulling timing down low (KR). I want to make sure everything is running properly before tuning. I think I might look into the tuning though and see if maybe a PO has put a chip in her that isn't tuned right. She did have 180k+ miles when I got her and that gives a lot of time for POs to tinker with her. Her seats were also changed to 94+, she's been repainted, plus the exhaust so I'm sure she had someone playing with mods. Also her opti, waterpump and intake gaskets had been done recently by the PO, poorly I might add. So who knows.

 

I can't help wondering if there isn't something rattling that is faking out the knock sensor(s). Have you gone over the car thoroughly to check for loose bolts, broken brackets, etc?

Live well,

SJW

 

I have gone over her thoroughly. She is pretty tight now. The exhaust actually fits very well and doesn't hit the cross frame that is on the convertibles. Motor mounts were loose on the bottom supports but that had no affect. I have had the whole front of the engine apart and even replaced the balancer as the rubber was shot. I don't know what flywheel is on her but it is quiet. No chatter or noise from there.

 

Any valvetrain noise? Stamped rockers or roller rockers?

I chased false knock that showed up as soon as I came off idle… turns out Comp Pro Mags are noisy roller rockers. I did an absolute ton of data logging to distinguish real knock from false. Dialed the timing back till what I determine was real knock was gone, then desensitized the KR via the tune to take out the false KR. My false KR was happening under 3k rpm at part throttle. It really made it a dog, once resolved it a was different car. Can’t tell you how disappointed I was in my cam till I got it squared away!

There is an LT4 knock module that is supposed to help. I’m lucky enough to have bought one many years ago. Not sure if they are still available. That said it obviously wasn’t a cure all as I still had to deal with it in the tune.

 

I have stock rockers. I replaced the lifters thinking they might have lost their compression, but that didn't help. I am going to try figuring it out in the tune. I just got to learn to be gentle with electronics. I ruined the pins in the prom base.

 

The tune may be your solution. It was for me, my recommendation is to datalog A LOT, as many conditions as you can. Make small changes to the spark table and datalog again. You should be able to flush out real knock from false knock. Dial out the real knock. Then, what I did once confident that all I had left was false knock, desensitize it by reducing how much spark it can pull.

It was easy enough to find the false knock because it showed up in every datalog no matter what changes I made. Even drastically pulling timing. I did this while tuning my cam and it made a world of difference.

 

All sounds great, but I am still not sure how to get to the tuning part. I know I need to research on tuning forums more. I have started, but get lost in technical talk. I need to find a simple walk through guide. At this point I am still lost on what I need to do to get the info off my chip and use the G1. My stock chip is the (I think 32 pin) and then there is another chip next to it that only had 6 pins. The G1 only has a socket for the 32 pin chip. Much to learn, I still have.

 

Once upon a time I read this as a start
http://www.lt1pcmtuning.com/tips/

but there is a TON to learn. I’m not expert by any means. I started with a mail order tune and then dialed it in myself to really nail it down.

being a 92, a little more tricky on the hardware front and not a simple pcm reflash. You’ll need a chip burner. I had a 91 GM car yes ago that I used a Moates setup.

 

Thank you for the link. That is where I started. That lead me to Moates and I got the hardware from there. I am using TunerPro and the lt1pcm tuning site seems to focus more on the other software programs.

 

I finally solved the kr issue. I bought another chip from the for sale section. It is a performance tuned chip, but looks stock. Maybe a home tuned chip. But it works great and I don't have the turbo issue I did before. Plus when I cruise at 65 and go up a hill on the freeway it holds 65 no problem. Before I would have to downshift to 5th. I even was able to creep up to 70 on that hill with just a little more pressure the pedal in 6th.
I still need to figure out this tuning for myself. One of these days...

 

VERY NICE! That could have taken many people (including myself) a LONG time to figure out! Great job!