I seached this forum for anything related to Knock retard. Most of the results came up with UFC battles. So I am posting a new thread. Last weekend I finally got my NX kit wired up and was running it on a dyno. I managed to record my last scan on a 150 hit. I sent the scan to a buddy of mine and he noticed that i was getting knock retard right after the spray kicked in. About 1.7 acutally. My question is what changes can I make to my tune to adjust the KR? I am new to tuning so I am trying to figure this out as I got. My bud told me I could look at tuning the PE table. But by how much?

Thanks for any input.

Nakoz

 

I guess no one knows or should I be posting this in the Nitrous section???

 

We'd really need to look at a log of some sort to see where it was, and what the other conditions were to make a good guess. It sounds like you need some extra fuel on the hit to me. How are you tuning your car?

 

you should have retarded the timing 2 or 3degrees at least for that 150 shot if you have not adjusted your timing tables. You can add more fuel it may get rid of it or it may not depending on how much power your pushing. I doubt youve reached the limit of pump gas but be realize it does have a limit.

 

Not necessarily...the stock tables are pretty conservative. I would feel relatively safe running a stock '02 timing table without pulling anything, as long as you are staying with that kinda shot.

I would lean towards the timing table as an issue if he was getting knock any other place than the hit.

 

Considering he's asking these questions(because of this I would figure hes new to tuning) w/o seeing the car personally I would be conservative. The best way is to put it on the wideband and get the true readings. If you doing it off of knock sensor reading I would stay conservative. Pretty sure every shop across the boards pulls timing for Nitrous even though its safe up to 150 on a wet shot. I have quite a few friends who run 150 out of the box with no tune.

 

First off, thanks for all the responses. I was worried no one would respond to the post. To help some on the topic here is the scan I took from my car with HP Tuners on a 150 shot:

http://www.louisianaperformance.com/.../NX150_Run.hpl

Here is the Tune that I ran it on:

http://www.louisianaperformance.com/...Roy02SS_NX.bin

and Here is my daily driver tune:

http://www.louisianaperformance.com/...ng/Roy02SS.bin

That should help out with what I am running with. If you look at the tune for the spray I am already running with about 4 degrees less timing then my daily driver tune. That is why me and my bud where leaning a litte more toward the PE tables. The scan shows the KR when it goes WOT. My window switch kicks in at 3200, when the knock starts, and shuts off at 6400.

Any suggestions?

Thanks,

Nkz

 

Anyone?

 

Well you dont really start knocking till you hit almost 4000 where you go 1.1* retard, the intial burst after you spray was only a mere 0.2* retard.

 

If you look at your dyn cyl air on the scanner right before the juice hits you are like .59-.60 g/cyl and on your spark table that corressponds to 27* exactly what is showing on your log file. You pulled the 4* of timing @.68 g/cyl and 3600rpms. Pull a little more timing in the corresponding areas and you should be fine.

There were actually 3 knock events. You could add some fuel there, but are probably better off pulling some timing in the corresponding areas on your Hi/and lo spark tables since you copied them to one another.

Dougie

 

First off, you need to get the car on the dyno and find out what your true AirFuelRatio is. If you are running a bit lean, then decreasing timing a couple degrees is not going to help much in the long run. Make sure that when you spray, you are BELOW 12.0:1 AFR.

IMPORTANT: Have you upgraded your fuel pump? If not, then you need to get a Walbro or anything better than the stock pump. A 150 wet hit is too much on the stocker and you might be running just a little lean which could be why you are seeing some retard.

But either way, if you are showing 27* or more, you really should back it off at most to 25 on the hit or get a timing tuner box that activates with the spray that will only retard when you spray.

Once the fuel is verified...
Then find out where it is showing knock by looking at the histogram in the HPT Scanner. Anywhere you see knock, edit the appropriate cells in the HPT Editor. Lower timing 1 degree at a time.

 

Good point if you dont have a fuel pressure gauge just run a manual one from the valve at the front of the fuel rails and tape it to the window. Run it see if the fuel pressure drops.............Us turbo guys have to do this with our cars if we dont have a fuel gauge. Luckily I started out of the box with a dual walboro setup so fuel was never a problem.

 

WOW, thank you guys for all the responses!! GTODoug, thanks for telling me about the timing on the .59-.60. At first I was wondering where you found it was at .59-.60 @ 27 but then I looked at the histograph of my scan and saw what you were talking about.

To answer a few questions, currently I do have a Walbro 255 pump and I do have a fuel pressure gauge. My AF was about 13.5 when the spray kicked in 12.5 at 4800 and 12.0 at 6500, according to the AF on the dyno. Now according to SSnakeKiller I want to be around 12.0. So I am running a little lean. I know I can adj the timing down, but how would I add more fuel during the spray and in what tables and how much? Sorry for my ignorance, but I am just learning. I really appreciate everyones help.

 

Sounds most likely that your N/A tune ramps down quite a bit. Try to get the N/A tune around 12.9-13.1 across the board.

This is a recent 04 Z06 I tuned, which also had a bad downward sloping AFR curve before tuning, and as you can see, it is very nice after:

04 Z06 Dyno Sheet

That is a good example of the AFR you want.

Then, when you hit the wet shot, your AFR should be more steady and more around 12:1 (ideally 11.5-12.0) the whole way across.

edit: To scale the AFR, look at the power enrichment table in the Fuel Table. It will be something like PE vs RPM. It is one row. Scale the appropriate cells according to the rpm you want to adjust fuel at. Example: If you want to adjust 4400rpm to ADD fuel, highlight the 4400rpm cell and in the box at the top put 1.03 and click on the X (multiply) button. This will add 3% more fuel at (and around,avg) 4400rpm. Only make SMALL percentage adjustments at a time. Once you get used to it, you can add 5+% at a time, but for now stick with 1-3% so you get the hang of it.

So in your case, it sounds like you need to add quite a bit at the lower rpms, a little less in the middle, and barely any adjustment needs to be made at the top.

 

Thank all of you guys for your info and expert opinions. You guys have got me going in the right direction and I think we got this thing figured out. Now we just need to do a little tweaking and my car should be right on the money.

Thanks again, I learned alot

Nakoz