Reduced engine power help

[Raddtadd]

Every time I build much boost my engine goes into reduced power mode. I'm doing speed density tune as well. Anyone have any ideas?

[5FDP]

You'd get more help if you have logs and the tune file.

And the complete setup on the vehicle helps too.

[Joshtuning]

this should help you out if you haven't done it max out calculated air mass vs tps vs rpm st.png

[Raddtadd]

lsx376 B-15. whipple supercharger with BorgWarner 86mm turbo. snow performance stage 3 water/meth kit. with all supporting mods. it also stumbles a lot.

[68Camaro]

whipple supercharger with BorgWarner 86mm turbo

really?

[Raddtadd]

Yeah the drive ability is unreal. Instant boost.

[68Camaro]

post a pic
I grew up in Missouri - the "show me state"

I have seen blower/turbo/nitrous multiple power adder stuff before - usually show car stuff. doesn't really work well in real world applications tho

[Raddtadd]

IMG_1757.JPG lsx376 b15 twincharged. Detroit diesel been doing it for years a long with Nissan and other companies. the same idea as compound turbos or superchargers except twincharged has higher average power and easier drivability.

[mowton]

What code(s)? Some are related to airflow vs TPS (tables available to us) and some are related to TPS rationale testing (expected TPS position vs actual). In high boost applications, the boost pressures on the throttle plate can actually force them open/close and throw off the validity test. Normally, if it is the later, other than a Throttle body mechanical issue, you need to reconfigure the setup to a Drive By Cable....:-(

Ed M

[Raddtadd]

It comes up as MAF/ tps correlation if I remember right. And that would be sucky if I had to change haha

[68Camaro]

Try maxing out MAF Cylair table to 4.1
also PO121 Error Max Map - set to 100
and PO121 Error Min Map - set to 0

these are found under ENGINE DIAG>GENERAL

if it still goes into REP after these changes log g/cyl airmass and see if it going above 2.32 g/cyl (even if it gets close to this number in you log this is the problem)
this will cause REP on this operating system (even if you have these tables maxed at 4.1 g/cyl) - I think it is a glitch myself but you can tune around it by scaling the injector IFR data and the VE table and trick the PCM into thinking you are flowing less air than actual and the REP problem will go away

Unless of course it is blowing the throttle blade open or closed as Ed has suggested - if that is what is happening then I agree it is time for cable

[Raddtadd]

Sweet I'll try it! I maxed out the MAF table and that helped tremendously. But I'm compounded so I hope it's not closing or opening the throttle since I'm only at 15-20 psi max. But thanks guys

[mowton]

15 to 20 lbs of boost could do it. Dtc p1515/1516 (IIRC) are the non air type dtcs....

Ed M

[Raddtadd]

So if I have those codes then that means my throttle is opening or closing?

[mowton]

Most likely as these are developed by the TAC module which we can't program.

Ed M

[Raddtadd]

How hard is it to switch to a mechanical throttle body?

[mowton]

Check to see if your P59 PCM has these numbers -- Serv. No. 12586243 Hwd. No. 12583659...and should have Red and Blue connectors. If so then you should have the IAC drivers on board. Express Vans used the DBC. There are some good how to's on line. You need to edit the tune in System>Vehicle>system options> and set the GMT800 ETC cell to 0. Add the wires to the IAC and TPS per the attached. This is the top level approach.

Ed M