Gave the GVR-4 some TLC today!
 

I have been battling a nasty knock problem since I got the car months ago. I would max out the knock count with even stock boost settings and I was adding uber fuel via my 5 knooby AFC. Today I finally got around to investigate possible causes. The very first thing I checked turned out to be the cause. For some completely unknown to me reason, I was 17 degrees base timing. How it got that way, I have no idea. But after resetting it to 5 degrees(oddly enough I was still getting 10-15 degrees without the pin grounded?) I had to change my idle, which got rid of my idle surge(yay!). I then proceeded to change the plugs to BPR7ES's, I had hoped these would help against knock(without trying the timing first). While I was there I did a compression test, which mildly depressed me. 145-160-145-125(125 being closest to the T-Belt). Hopefully it is just valve seals as all the old plugs came out looking fine.

I cleaned up, fired her up and went for a test drive. I zero'd out the AFC and made some 2nd and 3rd gear pulls up to 7k with nearly no knock until the top(where it was only at worst 7 counts, nothing some time with the AFC can't fix).

All in all I am much happier with the car now, although I have to worry about that one cylinder, plus a new coolant leak I found coming from the front case(hopefully just a water pump so I can't my ass around to changing the T-Belt too). But I have a new found love for my GVR-4 which I haven't had in awhile. Who knew stock boost could feel so good.

Thanks for letting me share, and if anyone has any comments, feel free to share. :)

Re: Gave the GVR-4 some TLC today!
 

Good to hear, i am running one of those too. I also am getting a little more knock than i would like. You say changing the idle made a difference, how did you go about using the idle to change your results. My base with pin grounded is at 5 but when i unground it it goes up to 10-15 like yours.

Thanks, Erik

Re: Gave the GVR-4 some TLC today!
 

Well first, I had an idle of right around 900 with the timing pin grounded. But this was with 16 degrees of timing. When I changed it 5 degrees, my idle went down to 600 and was very lumpy. So when I cranked the idle back up(grounded the pin in the diag connector in the car too) I was for some reason at 7 degrees. I then changed it back to 5 degrees and then voila, no more idle surge. I don't really get it myself. Interesting how the timing being off that much affected so many little things.

I think the 10-15 ungrounded is normal on a GVR-4 as they tend to have much more aggressive timing maps than a DSM, or so I have seen by my little looking around.

Re: Gave the GVR-4 some TLC today!
 

Good job on finding the problem.

By the way, valve seals don't affect compression... Did you mean the valves themselves, where the valve meets the valve seat?

Re: Gave the GVR-4 some TLC today!
 

Right now I am hoping it is just about anything besides the motor needing to be rebuilt. I can't afford another one now, or in the near future.

Re: Gave the GVR-4 some TLC today!
 

alright i will have to look for some other things that go into the kock causing category then, thanks for the info tho