I may have figured out my detnation and lean AFR problem.....

[The Rock 326]

Yea, the F/P seems fine(in the 40+PSI range @ WOT). I'm going to get with Doug, and add a 3rd. tune(cold weather). I woud like to take out 2 degrees, and add some fuel. I think the dyno temp has a lot to do with it. The day of the dyno, it was quite a bit warmer(60+ degrees). The days it detonated, it was in the 20-30 degree temp range. It didn't seem to detonate until I got it over 5lbs. of boost. I drove it on one of the warmer days 2 weeks ago when it was in the 70's, and got in it, and it seemed to do fine.


Whit, is that about the same with yours?? Didn't yours drive fine on the warmer days??

[QWKSNKE]

Do you have your dyno graphs? I would like to know what your a/f is tuned to

[tacbear]

Originally Posted by QWKSNKE

Do you have your dyno graphs? I would like to know what your a/f is tuned to

Both of our cars' AFR run pretty straight from 11.5 to just under 12. Up until I went to the track whenever I would get in the boost my WB Commander was rock solid 11.8-11.9. Also I recieved my new pump today (it is the complete assembly-bucket,sending unit and fuel tank cover) and the "bucket" assembly is completely different from the one that Dave got me, whichs tends to confirm that I have the wrong pump!

On the Dyno Sheet it looks like the AFR goes over 12, but I laid a straight edge across the graph and the AFR is at 11.5 at 4000 rpm and just touches 12 at 5200 rpm. The blue line was my final tune.

[QWKSNKE]

If it were me ( and this is the way I do mine) I would have it tuned where it is no higher than 11.5-11.6 in the upper rpms on the dyno.

Generally speaking, it seems that you can usually get away with a 12:1 a/f up until 4000 rpm then have it slope down to 11.5 around 5500 and hold that flat. This seems to work well to help battle potential lean detonation when on the road.

[tacbear]

Originally Posted by QWKSNKE

If it were me ( and this is the way I do mine) I would have it tuned where it is no higher than 11.5-11.6 in the upper rpms on the dyno.

Generally speaking, it seems that you can usually get away with a 12:1 a/f up until 4000 rpm then have it slope down to 11.5 around 5500 and hold that flat. This seems to work well to help battle potential lean detonation when on the road.

I agree with you 100%.

[QWKSNKE]

That's a cool pic Whit

[The Rock 326]

Not trying to jack your thread Whit.

Here's my graph for comparison. Dunno if you can tell the AFR or not??

BTW, nice pic of the Stang!

[QWKSNKE]

Originally Posted by The Rock 326

My graph. Dunno if you can tell the AFR or not??

From what it APPEARS, your a/f could stand to be dropped down a little as well.

[The Rock 326]

Originally Posted by QWKSNKE

From what it APPEARS, your a/f could stand to be dropped down a little as well.

I'm gonna get with Doug, and dyno it again.

[Wicked]

Neither one of you have intercoolers right?

What is your timing? A lot of tuners like more timing and fuel, and some like less timing and less fuel. Its all a balancing act. You may need to take timing out of it, not fuel.

My car is kinda like a poster child for how long a car can run with a pegging MAF and 12.5-13:1 AF at high rpms with 13 psi of boost. No pinging ever, cold or hot. I am also running the lowest timing I have ever seen on a car like mine and I believe that's the key.

Chris Johnson, president or whatever of Superchips and found of Johnson Motorsports(JMS CHips), tunes like this.

My point is, a 12:1 AFR is not lean at the boost levels you guys are running and timing makes heat too.

My .02.

BUT, because of your pump situation, you my actually be running lean. :-D