I've been playing with EFI for a couple weeks now but no matter how high I set the boost tables, my boost seems to be capped at about 25-28 psi.

Is there a PID that I'm missing?

hmmm playing with "Desired boost" tables should give you all the boost you need...

hmmm playing with "Desired boost" tables should give you all the boost you need...

And then some right??):h

1) How did you determine your boost is capped at 25-28? Via Flashscan or a boost gauge? You do have a real mechanical boost gauge, right?

2) Use PID named CALC.ACTBOOST, it should be consistent with your boost gauge.

3) What table have you been making your changes in, Desired Boost Levels (A), (B), (C), with EGR On or Off?

OK

1). Both. My flashscan and Mech. guage cap out at 25psi.
2). Yes.
3). Table "c" EGR off. I've dissabled my EGR.

I have controll over the desiresd boost pressure until 25lbs. I can eliminate it, I can build boost at very low RPM, I just can't seem to get any more than 25lbs.

Oh, and I do have a blocker plate.

Is there a way to check the sensor feedback? Maybee my sensor is dead and caping off at 2V or something.

1) Are you logging any turbo vane PID's?
2) Does GM.TCVPOS follow GM.TCVDES?
3) Does actual fuel rail pressure match or closely follow desired fuel rail pressure when boost is capped?
3) Have you compared logs of stock tunes to your modded tunes?
4) There is a boost sensor voltage PID and although stranger things have happened, I can't believe you have an intermittent sensor that consistently caps your boost at a specific level.

3) Does actual fuel rail pressure match or closely follow desired fuel rail pressure when boost is capped?

I've always wondered about this causing a drop in boost pressure while at WOT.

OK

3). Table "c" EGR off. I've dissabled my EGR..

I thought someone said that the truck will still use the table "c" EGR on even if you dissabled the egr. Please correct me if I am wrong.

I found it here. http://efiforum.iqd.co.nz/showthread.php?t=2154

I thought someone said that the truck will still use the table "c" EGR on even if you dissabled the egr. Please correct me if I am wrong.

Sorry, incorrect.

I've always wondered about this causing a drop in boost pressure while at WOT.

Not saying this is the case, but as an example I dug up an old log that shows rail pressure dropping during a WOT run. If you calculate the actual boost by subtracting GM.BARO2 (14.2) from GM.BOOST_DMA (37.4) you will find my boost tops out around 23.2psi, although I was commanding approx 30-32psi when this occured. I have a feeling boost is being limited by an underlying factor and it will take a little digging to figure it out.

Dave

I thought someone said that the truck will still use the table "c" EGR on even if you dissabled the egr. Please correct me if I am wrong.

Defining disabled as mechanically defeated, then yes. If you program it not to activate then it should stay in the "off" tables.

You can program it by vane position and it will go higher. I have not tried doing it by desired pressure.

You can program it by vane position and it will go higher. I have not tried doing it by desired pressure.
I'm not ready to do that yet. I'm starting on the Sensor scale to see if I can tweak it up a couple PSI.

Defining disabled as mechanically defeated, then yes. If you program it not to activate then it should stay in the "off" tables.

Thanks for clearing that up.

I'm not ready to do that yet. I'm starting on the Sensor scale to see if I can tweak it up a couple PSI.

Please keep us posted on your findings.. I looked at doing that too.

Please keep us posted on your findings.. I looked at doing that too.
Hopefully in the next few days. It's raining here right now.

I had a little time durring work to fool around with it.

I logged both vane possition PID's and the vanes are dropping right down to 12%. (desired and accual)

My fuel rail pressure seems OK.

Only if I change my minimum vane possition, I can get the boost up past the 26.2psi it is getting capped at.

I did notice that I had a pending transmittion trouble code that I didn't notice before. Maybee that has something to do with it.

Oh, and my EGR is dissabled electrically.

I had a little time durring work to fool around with it.

I logged both vane possition PID's and the vanes are dropping right down to 12%. (desired and accual)

My fuel rail pressure seems OK.

Only if I change my minimum vane possition, I can get the boost up past the 26.2psi it is getting capped at.

I did notice that I had a pending transmittion trouble code that I didn't notice before. Maybee that has something to do with it.

Oh, and my EGR is dissabled electrically.

Ben was able to get pretty big boost numbers when he blew his stock turbo. I'm not sure what's going on with the tables but I'm not going to push it beyond the calculated max yet.

I had a little time durring work to fool around with it.

I logged both vane possition PID's and the vanes are dropping right down to 12%. (desired and accual)

My fuel rail pressure seems OK.

Only if I change my minimum vane possition, I can get the boost up past the 26.2psi it is getting capped at.

I did notice that I had a pending transmittion trouble code that I didn't notice before. Maybee that has something to do with it.

Oh, and my EGR is dissabled electrically.

P0299?

Please post the code you had. Also, I disabled the boost check via C0801 @ 300, C0802 @ 8000, C0803 @ 0. Clear all your codes and run it with these tables changed. You should not get any boost codes after that.

The code was not a 0299. I bumped that DTC up to 9PSI delta.

Just for giggles, I changes all the boost tables, and it still caps @ 26.2psi.

Could it have anything to do with timing? I haven't got mt head around the timing tables yet so I haven't done much with them.

Could there be a missing PID?

0299 is kinda a MAF error even though it claims to be a boost error.

Stock trucks will get it with certain intake mods. Be aware that a full on 299 will "defuel" the truck a bunch. If it has a full blown 299 active (even if you disable the trouble light), it is possible it would limit your boost just because of insufficient fueling to spin the charger high enough.

Thanks McRat,

I'll look into the MAF.

Something don't seem right...use the scan tool and hit shift F11. Do this with just the ign. on....then check for codes (shift F8)....you should get no codes...then start the truck...check for codes....see any? If not, go out for a drive then check for codes. If it is being limited it is a code or B2222, B2223, B2224 unless you are changing something wrong, flashing wrong, or your boost gauge is hosed. If all else fails, try changing the B and A tables once.

My MAF is dissabled. Is it supposed to be?

The only code was a "pending" trans code.

I cleared all codes and adjusted all boost tables.

Both my mech. guage and EFI read the same boost pressure.

Could it be a MAP thing?

MAF disabled?? :confused:

MAF expected air flow ECT enabler 302Deg.

MAF expected air flow ECT enabler 302Deg.

That is a factory setting. What are your B2201, B2202, and B2203 settings? Do you have anything aftermarket on the truck...ie: Edge, boost stick, VA...Etc? What version EFI are you running? Go download the tune out of your truck and see if it matches the tune you are putting in. Try tunig with all 0's in the table and let us know if you get any boost. I'm running out of ideas. HELP!

B2201 = 10.2
b2202 = 11.9
b2203 = 13.6

Nothing aftermarket.
EFI 7.3
If I set the tables to 0 boost I can still build some boost based on the minimum vane target. But not much.

No codes

Is the fingerstick off? Did you check all the wires to make sure nothing got cut or damaged? Can you post a snapshot of the table (B2206) you are changing for boost so we can see the values you have entered and where you entered them?

b2206

Opps didn't work.

17526

Here is the tune that is in the truck.

I don't know how to break out just one table.

Try this one. I only modified the C boost w/ EGR off table. You can check the history and see what I modified.

Here it is

Change the B2225 back to stock...50 is way too much there....use stock for now. Also change the C0801, C0802, and C0803 tables like I said to try before. I also noticed your Fuel psi base tables are at 176MPa...change those values to 160MPa max. In table B1010 the last value at 60000mm3 per second can be set to 400 instead of 0. This was in one of GM's updates.

Change the B2225 back to stock...50 is way too much there....use stock for now. Also change the C0801, C0802, and C0803 tables like I said to try before. I also noticed your Fuel psi base tables are at 176MPa...change those values to 160MPa max. In table B1010 the last value at 60000mm3 per second can be set to 400 instead of 0. This was in one of GM's updates.

The B1010 value change was most likely done to reduce type II P1093's (too much pressure). By increasing that number, it DECREASES target CP3 output.

The 176mpa probably has no effect either way. Attempting to set it past 160 did not change actual rail pressure, and dances at 160. You can make dance at 150, 160, but something stops it from dancing any higher.

Dance - going back and and forth across the target number: 148 151 155 159 163 161 159 160 160 160 160

Please don't mistake this for a final product. One of the things I'm currently playing with is fuel pressure.

The b2225 was to see if the boost would start to climb after the vane possision hit min. It did.

BOBO,

I 0299ed as soon as went on the highway.

I logged it if you want to see it.

I also logged my original tune if you would like to see that as well.

BOBO,

I 0299ed as soon as went on the highway.

I logged it if you want to see it.

I also logged my original tune if you would like to see that as well.

How much boost did you get. The P0299 shouldn't have done anything to performance.

You changed the C0801, C0802, and C0803? Post the tune you set the 0299 with. I'll look at it. You might have another problem.

How much boost did you get. The P0299 shouldn't have done anything to performance.

OK! I found out that it will. I think the P0299 sets a "Engine protection Stage '1' Fuel Limit" which is table B0733. Playing with the boost sensor scaling caused this on my truck. I guess I need to get rid of the boost error checking.

Did you get it to work?

No I did not diasble the boost error on this run.

The boost capped at 25psi, but came on nowhere near as fast.

You should add the actual boost pid to your log files.

I repaired the file as you asked and loaded your boost table and it seems to work properly.

Now my only question is why???

:duh:

I got it now.

Thanks for the help everyone.

This place rocks.

What was the explanation?

Engine limp mode?

KB,

I was reading and programming for the wrong PID.

Glad you got it working.

Thanks for your help bobo

Please post the code you had. Also, I disabled the boost check via C0801 @ 300, C0802 @ 8000, C0803 @ 0. Clear all your codes and run it with these tables changed. You should not get any boost codes after that.

Changing these tables got rid of my o299 code problem also, thank for all the good info Bobo!

Still having 0101 code problems though?

Later,
Caleb