Gave the GVR-4 some TLC today!

[Alpine TSi]

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. :)

[GVR-4579]

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

[Alpine TSi]

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.

[Matt D.]

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?

[Alpine TSi]

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.

[GVR-4579]

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