Before I start, I'd like to say that I'm not here to knock Al. I like Al. He's just a part of the story. Al, keep up the good work.

I had my car tuned by Al about a year ago on Buschur's dyno. Everything seemed to go OK. The AFRs looked good on the tailpipe wideband and the ECU wasn't pulling any timing. Everything was good.

Fast forward about 8 months. I get a wideband about the same time ECUflash was released. I haven't modified the car since Al tuned it. The AFRs on the wideband looked a little fat too me and I didn't really like the way the timing maps looked. I figured that I had a small leak in my exhaust that was causing Buschur's wideband to show a little lean. So, I start editing a stock map. I get the AFRs graphs where I like them and the timing seemed OK. I was showing some knock(<6) at WOT up around 5000-5500 RPM. Even when I fattened it up and pulled some timing in that area, it didn't seem to help the knock.

My Buschur downpipe sits very close to my diff housing. I started assuming that his could be the source of the knock. This is something I have to live with because David doesn't seem to want to fix the DP for me. I've thought about getting another DP from another manufacturer, but I don't want to spend the money if that's not the source of the knock.

I got to thinking last night that I didn't throw Al's tune out because it was knocking. I didn't even log it for knock before I started on my own tune. So, I decided to put his tune back in to see if the knock would go away. It got worse. This leads me to believe that the problem might not be the tune. I think it could be something else. Why else would Al's tuning session show that no timing was pulled and now it's pulling it like crazy.

I've been logging with ecuedit. If anyone would like to take a look at MY logs to see that I'm not way off base with the tune, I'll email them to you. I'll also send you the ROM from the tune. I won't send any of the logs that use Al's tune or Al's ROM.

I've got some autocross and track days coming up and I'd like to get rid of the knock before I start pounding on it.

 

Show logs.

 

Buschur 3" exhaust with high flow cat
272I/264E GSC cams
Walbro 255lph Fuel Pump
Hallman MBC
Weapon R engine stabilizer

I didn't log the 2-byte load on this run, but it's running around 230 and tapers near redline.

 

This is a log I did using Al's ROM. This is just to show the Load. Since I'm using a MBC this shouldn't change much with the tune. It doesn't show any of the tuning info. The values in the cells are the throttle positions. Load is the X axis and RPM is the Y axis.

 

What I would try is to throw some race gas with your map that has only the 6 counts of knock and see if it goes away. If it does go away, then it is tune related of course.

 

From the looks of the log, it appears that you have a jump in your timing map from 5 degrees to 10 degrees somewhere around 5500 RPM.

That's the point where you go from 2 counts of knock to 9 counts of knock. Maybe smooth that transition a little bit.


Eric

 

Looks like excessive timing to me as well. 7* in peak boost is too much and it's hard to tell what it tranistions too when your knock counts get high but your carrying knock through your entire powerband. What boost and what fuel are you running. Flash it with the stock map and log that or post your timing map so we can see what's going on.

 

Thanks for all the replys guys. I think I just got a tank bad gas that was causing the unusually high knock counts. I ran the car close to empty and filled it back up with 93 octane. The knock went back to normal. I still have a bit of tuning to do. I'll try to post up some logs from a good tank of gas to get your opinions.

Of note:
- the 2-byte load hack kicks ***!
- I bought 5gal of 100 octane to test/play with

 

Here's a few logs on the good 93 octane gas. How do these look?

 

So, no one has any comments or suggestions? I'd really appreciate it.

 

From the posted log, i see knock counts of 1-3 above 5500. I would back out the timing 1 degree from 5700 to the top in the appropriate load cells.

I would also run repeated pulls back to back without cooling down like 5 or six 1-4 gear WOT. Then check the knock counts on the last pull. If you get much more i would look at the fuel a little.

Most people would say you are running a little lean, but 11- 11.3 above 5500 seems OK as long as the timing is in check.

Just to be sure you might replace the fuel filter.

My .02

Milburn