I was helping a friend apply the NLTS patch this weekend and we ran in to a repeatable knock occurrence related to the NLTS mod.

Basically, when shifting using NLTS, the 2-byte load reported ~140% to 160% and the timing jumped in line with the load/RPM cell. When the clutch is disengaged, the timing jumps back to the WOT cell (~250%) and the timing of course follows.

The knock occurs in conjunction with the timing shift and I feel that it's pseudo-knock and not really dangerous. Here is an example ...

timing - Knock
7 - 0
8 - 0
9 - 0
10 - 0 (begin shift)
16 - 0 (lower load cell)
8 - 5 (back to WOT cell)
6 - 4
5 - 3

It's common for a drastic shift in timing to induce knock and I'm positive that this is the issue. But, even though this isn't caused by detonation, timing is still pulled for a couple of seconds while the knock is counting down.

Now, a solution would be to identify the problem area in the lower load cells and reduce timing there to reduce the timing shift while the clutch is depressed. I played with this a little, but in order to "flatten" the timing on a shift the lower load cells would actually need to have lower timing values than the higher load cells on the same row ... this just seems backward to me and I didn't go too far with it ... I decreased the timing in the lower cells by 2º-3º in the commonly referenced cells but the problem persisted since there was still a ~3º jump when the clutch engages.

So, I'm hoping that we can find a solution for this issue that does not involve odd transitions in the timing map. Any input would help.

Just to add, this happens on my car as well but not as often and the counts aren't as high. I occasionally see a 3 or 4 knock count on mine and we've seen up to 7 on his. Both cars are IX MRs with v.15 ROMs.

Thanks for any help guys ...

EDIT :: As posted in the main NLTS patch thread, my suggested solution is to add another value to the NLTS settings that dynamically pulls timing if all NLTS parameters are true ...

If NLTS = TRUE, then [Requested Timing] - Xº

This timing pull variable would be applied to any timing referenced while the clutch is depressed. Tephra, is this possible ... and, more importantly, is this a likely solution?

 

Its a fast timing jump, which often causes a bit of knock Ive noticed. TB, have you tried raising your NLTS rpm point, that could help and make it so it stays in lower timing cells.

 

RPM drop was 750 in both cars mentioned. Knock occurred whether limit was reached or not, though it was slightly less if the limit was not reached.

I think the increased knock values on his car has to do with a slightly different driving style, but it is still an issue.

 

you're going to have to pull way more that 2-3 degrees, keep going

 

As stated, I know that pulling more timing would "fix" the problem, but I don't think it's the best solution. I feel that pulling timing ONLY when using the NLTS function would be a much better solution ...

 

how much cruising do you do at 100-160kpa at 6000-7000 RPM?

 

I'm considering part-throttle boosting. I guess you aren't too likely to hit the 6k row if you aren't WOT, but I'd still like to have a smooth timing map. You do have a point though ...

 

I haven't noticed any ill effects in normal or aggressive driving doing it the old fashioned way. I'm not saying you need to bottom the timing out, just lessen it until the problem goes away. I wrestled with this problem a long time ago...quick shifts = knock as the clutch engages at high rpm and you see timing in the 20+ area at low loads.

 

I just followed the timing trace in on the spreadsheet and adjusted the columns to match that trace, so If it was 15-15-15-15-24-, I just kept it constant and eliminated the knock.

 

^^ nice work

 

If you read my post, you'll realize that I do understand that timing can simply be reduced in the map to band-aid the issue, but I'm hoping for an actual "fix." I did not have this problem before the NLTS patch, so the problem isn't technically the timing map, it's the NLTS patch. You with me? I'd like to actually address the problem and not just the symptom ...

I guess the real way to address the problem is to make the car not act silly when the timing jumps a little bit, but I have no idea of the correct way to go about that and there is no way in hell I'm touching the knock parameters ...

 

the reason why you're likely seeing it with the NLTS is because you're effectively shifting faster and the clutch is re-engaging at I higher RPM than it was before.

the problem is there for people who shift lightning fast in most cases. I'm not saying you shift slow, just something I've observed.
whether you adjust timing in the timing map or some secondary NLTS map tephra comes up with you're still changing timing and like I said, unless you're driving around at part throttle at 5500-7000 you're not going to notice a difference between either fix.

why make your rom overly complicated by adding another hack?

btw, personally I didn't like NLTS, it slowed me down and had some funky quirks but that's another conversation.

 

It's my MR that is having these issues with the NLTS. One other issue is that when in an aggresive driving situation the car bogs/hesitates when I am shifting from 3-4-5-6 between each shift...at WOT and am using the clutch to go back to almost WOT. In town driving when you can not use the NLTS for it's too dangerous however you still want to accelerate quickly. Now if I gently give some throttle no probs but if I go from WOT shift and back to WOT immediately the car bogs.
TB is doing an excellent job with my tune, ad I'm totally pleased with the capabilities of the NLTS and can't wait to try it at the drag strip to get me into the 11's.

 

mine didn't pop back into action after shifts with the NLTS either...I was faster shifting it manually. Maybe some adjustment to the NLTS parameters would help but I was missing gears much more often with it and before I learned some bad habits I went back to normal shifting.