basicaly my problem is this, im tuning my truck that runs up to 13 pounds of boost on a one bar map sensor, i can do this relatively easily becasue the boost stays consistent to rpm... most of the time. its a twin screw whipple so the problem is, when i hit the gas crusing and it downshifts, the boost is right there and instantly hits about 9psi at a very low rpm. so it will hit 16 or 17:1 for a split second untill the shift is done, once its in gear and under load again everything is ok. is this something im just going to have to live with? is it safe? iv got plenty of fuel on tap, iv got a walbro high pressure pump and 80# injectors running at 30psi when the boost referenced regulator kicks in.

nobody?

I don't think anyone is going to say that the lean spike is safe... that's getting out onto a thin branch.

As for helping to cover it see if there is enough delta MAP for more AE. This may work because: as you hit the gas the MAP will increase with dMAP AE added. As the downshift completes the RPM will go up and the MAP will either fall a little or level out. That will stop the dMAP AE. Can try it and see how it works out.

With an auto more dMAP AE can be used then with a stick trans. Less likely to flood the engine with fuel from large dMAP transitions.

Hopefully the Walbro isn't one of these:

http://www.turbobuick.com/forums/gen...mp-update.html

RBob.

im going through my tables and i dont see any table for delta map? i do not have the 7747 ecm like in the older tbi pickups. i cant remeber what ecm i have right now but would this explain my lack of having a delta map table?

nobody has a problem with this but me i suppose?

You have the 7427 ecm.

You have a table that says acceleration enrichment vs. differential MAP...start with that.

Also, if you are in closed loop, you might want to richen up the o2 sensors on high map to help with that as well.

thanks yenko, i understand i just need to add to that to add more fuel, i see how you added some in your bin compared to my stock one. but i don't understand what Useconds means, should i just take this as an imaginary number? i like to understand what things mean...

Basically, its the amount of time the injector stays open to spray fuel into the engine......(just the basic meaning).

o, ok. so basicaly its how long the pulse width is... cool. makes sense now. my tune is coming along real nicely now, its nice now thats im familiar with the program and have a decent understanding of it all.

i started a trend, my brother and his buddy went in half on efi live to do their nbs trucks, ones a d max, the others a 6.0 with a cam. i was looking at the efi-live stuff, and man there is tons of info on that, whole tutorials and everything. im going off on a tanget, but anyways, thanks for the help once again yenko.

No problem....there are actually some tunes out there for the D-max for a better start.

Keep the D-max to a 80-100hp tune b/c anything over that and the Allison transmission will be toast.

With the 6.0L and cam (non-ls2), get the timing to about 22-23 timing and that will help the idle a lot and about 26-27 WOT(at first on 93 octane). Then its all about fueling.

i know, the diesel place has a whole tune library full of free tunes. my bro already has a diablo sport on the 120hp tune all the time, hes to damn stupid to listen to me, hes just itching to burn up a trans he cant afford to replace. the 6.0 has already been professionally tuned but he wants to tweek on it, and hes going to need to go through his shift tables when he puts new gears in, its just nice to not have to rely on the local dyno shop, their service just sucks.

honestly, i don't think they know what they are getting into lol, but you dont really have to on the duramax, you can buy a awesome tune for 100 bucks from kenedy racing and just load it up... and fry your trans. as for the 6.0, he could almost just not even touch the tune on that thing and hed be fine, and the duramax is more than fine with the diablo sport and the boost turned up, hes already ruined the turbo from playing with the waist gate and making 30psi out of the stock ihi turbo, now it backspins and every time you let off the throttle, the trans has been limped a few times also. so i think they both waisted money lol, should be interesting what they do to their poor trucks, especially the duramax.