Engine falls flat when going into boost?
Using a COS5 (?) with a base tune for a (GM) 4.3 turbo. 411 PCM set up for 2 Bar. Drives and idles fine until is sees boost and the engine will fall flat -practically stall.
Where should I start looking to trouble shoot?? Any specific tables or settings?
Appreciate any input.
Post your tune and logs, always the best place to start on here.
This is baseline received from a friend. Some data logging was done but not saved. I could not get the boost (PID) to function? I do however have a wideband hooked up to monitor while driving.
Oh it and it is a COS3.
Xtreme 7 may 2011.tun
This tune is a bit of a mess. What's going on with your boost VE table?
What lb injectors are you using?
What tuning method are you using, I'd go with speed density.
How much boost do you want to get upto?
Are you using an after market fuel pressure regulator that references manifold air pressure?
Answer these questions and I'll write you a new base.
This tune is a bit of a mess. What's going on with your boost VE table?
I dunno?Perhaps that is the problem!
What lb injectors are you using?
Stock injectors still in the truck. 32# @ 45 psi fuel pressure.
What tuning method are you using, I'd go with speed density.
MAF disconnected, so yes wanted to go speed density.
How much boost do you want to get up to?
Truck made about 14.5 from factory, so I would like to start there. (some guys running in the 20 psi range with stock block. Currently has mechanical boost valve and it is set low. (Like mentioned -falls on face as soon as it goes into boost)
Are you using an after market fuel pressure regulator that references manifold air pressure?
Yes, after market adjustable regulator based on manifold pressure.
Answer these questions and I'll write you a new base.
That would be might fine of you!!I would have taken it to a tuner, but finding a EFIlive tuner AND AWD dyno is not easy in this area. Only one e-mail was responded to when I propositioned tuner "stores".
Thanks for helping.
Doug E
What engine and vehicle is this in? I see its a 4.3 S10 tune, but that doesnt mean anything if its a swap.
First off, fix all of the out of range (OOR) cells. I had 6 pop up when I opened the tune.
And yes, where did you get that Boost VE table from? Highly doubt it would ever look like that. Have you read the COS upgrade tutorial? Things like the last column of your Main VE table MUST be copied over to the first column of the Boost VE table...
Do you have a wideband O2? For tuning any engine, but especially a boosted one, its a MUST HAVE.
I made some adjustments, I have no idea if the Boost VE table will push enough fuel now but at least its based off your Main VE table. I added anywhere from 10-30% to your Main VE table and smoothed the transitions to get the Boost VE table. Do you want it to pull spark when you get into boost? If so, look at how A0010 Boost Timing Table works. Dont know how much of an effect heatsoak has on your truck, I know for the TBSS its a major issue. Look at A0014 IAT VE Multiplier to adjust that.
If you have your wideband setup, look at WeatherManShawn's Calc.VET tutorial. Stay out of boost initially and get your Main VE table dialed in (need to see a log to determine its state now). Then work to the Boost VE table.
~Erik~
2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.
IFR has wrong value for the injectors stated in post #5.
The Boost VE table should flow off from the Main VE table with continuity... if you get the Main VE table more-or-less right it is easier to estimate the Boost VE table, and then fine tune it using a wideband.
To answer your original question in more detail, the Boost VE table contains way too much airmass (per cylinder), this causes overfueling, this is why engine goes flat in boost... there is like 4x the required fuel.
Thank you for the feed back guys -keep it coming.
The engine is a stock GMC Typhoon. 4.3 V6. 285 hp @ 4400 RPM :350 ft/lbs At 3200 RPM : Redline @ 4800 RPM (These values from factory) I believe these ran 14.5 psi boost from the factory
I have put the engine in my '02 S10 Xtreme converted it to AWD/4L60E. The engine controller has been replaced with the 0411 PCM (Gen III LS1) which is why i am where I am.
There is a lot to read on this site as well as outside sources, but eventually my head starts to spin with information over load. I do read and have printed out the EFIlive manuals. ( eg scan & tuning) Still waiting for the EFIlive for Idiots to hit the bookstore !!
Since I have recently become job-less I thought now would be a good time to do this since I can dedicate time to the truck and learning .
The wideband installed is the low budget one -AEM UEGO. It has yet to be hardwired into the pcm, or connected to the cable.
The overly rich state in the boost VE table was probably because it was out of fear of running too lean and trashing the engine.
Again -thank you for your feedback guys.-will follow up with all suggestions.
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