Stroker 1500

iTrader: (1)

Ok well to say the least im not to happy with my results. But i don't really want to talk HP numbers i have a tuning question. As some of you may have read i have had +6 ltrims for a while now and haven't been able to get rid of them for a while now when trying multiple different things. Well today i went to the dyno to see where i was at and to compare 2 different tunes. Well the first run i did with the mail order tune i recived ended up with a 14.5 a/f all across the board So then i loaded my second tune, the only difference was that the VE table had been increased by 15% and went from 1.15on the PE multiplier to 1.17 and ran it again. A/F was dead on where it was before 14.5:1 didn't change a bit. My question is why whats going on?

James B.

iTrader: (1)

Get a log of injector duty cycle. With a 383 I would bet you're maxed out on the stock Vortec injection.

You are running a stroked L31 bored .030 over with the stock manifold and injection, right? At +6 across the board there's not much headroom to feed more cubes with the the 19lbs/hr spiders.

FarmTruc

iTrader: (5)

I just tuned a 96 silvy , 383 stroker, head/cammed on Friday and I was able to get 12.9 a/f ratio with just a small tweak, his other tune was 13.8 across the board which is a tad too lean.
What tables are you changing?

thanks,

allen

Stroker 1500

iTrader: (1)

i changed the PE multiplier and then tried messing with the VE table

CHarris

iTrader: (5)

Does the 96 have a commanded AFR in PE table? A lot of the TBI trucks did and that made them very easy to tune the PE mode safely. If it has that table you just have to tell it what you want for the AFR.

Be sure to check your fuel pump too. We did a few 383's on TBI's and found that the fuel pump would fail pretty quick with the new load placed on it. I'd assume you're in the 80,000+ mileage club and the fuel pump becomes highly suspect with a fresh engine and increased demand.

Stroker 1500

iTrader: (1)

It has a brand new pump in it and i belive the PE multiplier is pretty much the same thing as the commanded AFR which is what i changed

CHarris

iTrader: (5)

Not really the same thing. The old Commanded AFR in PE would allow you to say I want 12.9 AFR or 13.0 or whatever you decided. If it only has the PE multiplier there is a lot more to it.

Here's a thought that I'll illustrate with my example. My truck has 42 lb injectors. We were able to obtain a global enrichment change (adding fuel everywhere) by telling the PCM that we had 40lb injectors. What happens if you try the same thing? It might help you out. Just a thought, anyway.

Stroker 1500

iTrader: (1)

I might have to try changing the injector size and see what happens.. I realize there is a lot more with the PE multiplier but i was under the impression that changing it should still yield a a/f change and it didn't on mine. The other thing that confuses me and makes me think its somewhere in the tuning is that it's never rich at any point and it doesn't start to lean out towards the top it actually gets slightly richer. If it was maxing out the injector wouldn't it start out rich and then lean out? here is my a/f graph



I apreciate the help so far. Farmtruc if you don't mind me asking how much power did the 96 put down and what did you change to bring the a/f ratio down? I apreciate all the advice and help so far

Thanks,
John

Stroker 1500

iTrader: (1)

TurboBerserker

iTrader: (1)

John,

A couple of things come to mind. Have your told the PCM you have more cubes? Have you played with the IFR, or MAF?

I would really suggest setting up a new VE table via the SD method, with an accurate IFR and an accurate MAF, now that you actually have better VE.

Also, how are your o2 sensors? Old?