Engine falls flat when going into boost?

[Dewglass]

:shock:

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.

[Evolution]

Post your tune and logs, always the best place to start on here.

[Dewglass]

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.




12248

[Evolution]

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.

[Dewglass]

This tune is a bit of a mess. What's going on with your boost VE table?

I dunno? :music_whistling_1: 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!! :thumb_yello: 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". :mad:

Thanks for helping.

Doug E

[ScarabEpic22]

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.

[joecar]

IFR has wrong value for the injectors stated in post #5.

[joecar]

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.

[joecar]

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.

[Dewglass]

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 !! :mrgreen:

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.

[Evolution]

Here's a base you might be able to start with. Do you have the factory tune, there's a couple of things I want to double check in the spark tables.

Disconnect the MAF signal wire if you haven't already done so, MAF wasn't failed in the tune.

I've used these figures for your IFR.
32lb/h @ 43.5psi with an actual fuel rail pressure of 45psi. Is this correct?

Start tuning your VE table and get the High Octane Spark table sorted before you hit too much boost. I've dropped your ignition timing down to 10 deg for now. Log Knock Retard and start building it back up again.

12253

[poconojoe]

Here's a base you might be able to start with. Do you have the factory tune, there's a couple of things I want to double check in the spark tables.

Disconnect the MAF signal wire if you haven't already done so, MAF wasn't failed in the tune.

I've used these figures for your IFR.
32lb/h @ 43.5psi with an actual fuel rail pressure of 45psi. Is this correct?

Start tuning your VE table and get the High Octane Spark table sorted before you hit too much boost. I've dropped your ignition timing down to 10 deg for now. Log Knock Retard and start building it back up again.

12253

Do you want copies of the stock timing tables for the original ECM?
These are going to be totaly diferant, since the motor originally had an OBD1 system using an ECM with removable chips, instead of a flash tunable PCM


This is the site most guys running stock ECM's use for tuning
http://www.code59.org/index.php

Here is a basicly stock tune for the factory ECM using code 59

[Evolution]

Was just wondering what ignition was being used, LS1 coil packs?
{B6001} Spark Dwell Time is different to what I normally work with.

[poconojoe]

Was just wondering what ignition was being used, LS1 coil packs?
{B6001} Spark Dwell Time is different to what I normally work with.

No, its a coil with a distributer, like the 1996 through 2001 vortec motors used
If you want a stock tune for one of these motors, I can post it, but it will be for a non-boosted application

[Evolution]

How did you go with the base tunes posted, are you getting anywhere with your tune?

If the car was running well with those spark tables, start with them.

I have never run an LS1 PCM with a distributor, maybe someone else can jump in and give some advice on that area?

[poconojoe]

2001 and newer 4.3's ran the LS1 style PCM with a distributor, along with the 5.7's in the vans, since the vans didn't get the gen3 motors, until 2003
If you want to look at some stock tunes for these motors, I should be able to dig some up and post them

[slows10]

Post up a few 2001 up if you could. That would be great. Are they bone stock tunes? Im looking for another 4.3 manual tune in a 02 up S10.

[Dewglass]

How did you go with the base tunes posted, are you getting anywhere with your tune?

If the car was running well with those spark tables, start with them.

I have never run an LS1 PCM with a distributor, maybe someone else can jump in and give some advice on that area?



Was hoping to load it this weekend. The truck ran well with the existing spark tables, but it is only when it went into boost things unraveled. Can't wait to try this out!

[poconojoe]

Post up a few 2001 up if you could. That would be great. Are they bone stock tunes? Im looking for another 4.3 manual tune in a 02 up S10.

I have noe that I could find for stick shick in 2002
This web site has stock EFI live tunes, but I didn't see any for 2002 4.3's with stick
http://www.tunefiledepot.com/

[Dewglass]

Update:

Initial start up was really rough and rich. So I wound up lowering the values in the B4001 table. In hind sight, the original values would probably work if I let the PCM learn a bit. I will include that tune, but only the one table was changed. (B4001)

Looking further into the injector values, Bosch has two flow rates for the same injector? (0-280-150-756) 30.55 @ 43.5 psi and 32 @ 45 psi (Note this injector is a replacement for the original GM part. Original GM injectors still in the truck)

Which leads me to the next confusion. Using the excel worksheet for injector flow I could not determine what "injector rated fuel pressure" meant ? Depending on that value it influences the whole set of injector flow values.

The truck was running okay at low boost ( < 2psi) so eventually I got it up to about 7 psi until the vacuum line came off -and freaked me out. It was repaired and then I realized this should be done with baby steps, so only a mild cruise and acceleration where logged. By the way, the log PID is based on the VE tutorial and the WB02 0-5v signal was wired directly to the V1.



12303


12304

12305

[Evolution]

Injector rated fuel pressure is what the manufacturer uses to rate their injectors.
Your fuel rail pressure is what you set your fuel rail pressure to or what your fuel pressure guage reads.

Once you have these set, modify your fueling from the VE tables.

[ScarabEpic22]

What Evolution said, DO NOT ADJUST B4001!! Set it according to the proper values for your injectors, then use the VE table to tune. Trying to adjust B4001 will mess up all calculations the PCM does related to fueling, you will have a horrible time tuning it correctly.

[Dewglass]

Injector rated fuel pressure is what the manufacturer uses to rate their injectors.


Where do I get this value?

The injector FLOW rate is available (also assuming this is 80% duty cycle)
Fuel rail pressure is available too ( As I control this via fuel regulator)

Injector rated fuel pressure ? ( Is this calculated or taken from manufacturer? -where do I find it?)

Depending on the value used for Injector Rated Fuel Pressure it affects the flow values.


12306

[Evolution]

Almost all fuel injectors are rated by the manufacturer in cc, g/min or lb/hour and are typically rated at 3bar (43.5psi). There are plenty of converters available on-line to convert cc or g/min to lb/hr.

Injector rated fuel pressure will almost always be 43.5psi
You will have to measure your fuel rail pressure, 45-58psi usually.
Then enter the lb/hr of your injectors.

When using a boost compensating pressure regulator, don't try and compensate for the increase in fuel pressure under boost with B4001. Do this soley of the Boost VE Table.

Hope this helps.

[Dewglass]

Almost all fuel injectors are rated by the manufacturer in cc, g/min or lb/hour and are typically rated at 3bar (43.5psi). There are plenty of converters available on-line to convert cc or g/min to lb/hr.

Injector rated fuel pressure will almost always be 43.5psi



Shouldn't this be a constant instead of a variable in the converter tables? :confused:

I adjusted the IFR and raised the fuel pressure to 45 psi (from 42) Although I have not done auto VE yet the fuel ratio seems to be in the ball park when cruising- although not going in to boost.

Since this adjustment cold starting is difficult? Is starts right away, but when the idle comes down it dies. I have to manually keep the revs up until it warms up. Idle seems lower to, but I did not change anything?

There is info on the forums for cold starting, but not sure if MAF vs speed density follow the same procedures. :confused:

The battery eventually died, so I had to quit while it charges.

Thanks for your help.