{C0801} & {C0803} Boost

[FUBAR]

Can someone please explain to me how these two voltages are in reference to boost? I am getting a P0299 Underboost code, and for the time being I rasied {C0806} up to 20 seconds to fix it and scaled down some boost tables. But I would like to know how the voltages tables translate in to boost. If voltage is below min for a certain time or above max then code trips meaning under/over boost and vice-versa. So is MIN translate to low boost and MAX high boost? And what would say .0142 V roughly translate into p.s.i. boost?

Thanks,

Andrew

[FUBAR]

Basically how can I tell "X" amount of boost will trip under/overboost code and how I can I increase that margin.

[Boost]

Hmm, I've looked in SI and the only thing I've found so far is that 299 sets when "The measured MAP pressure is more than 39 kPa below the expected range for 10 seconds". Did not mention anything about voltage. Maybe a bad map sensor?

[Boost]

Or you may have to do a Turbocharger learn. Just guessing though...

[FUBAR]

"The measured MAP pressure is more than 39 kPa below the expected range

Where did you find that? Under the page of where it shows MIN/MAX voltage settings, error time, and under/over boost delay time, I cannot find that. What {CXXXX} is that?

And what do you mean by, do a "Turbocharger learn?"

Thank you for the help.

[FUBAR]

This is the best I can find in the Tune tool. The kPa value your speaking of is exactly what I'm looking for.

http://i751.photobucket.com/albums/xx153/motocraneguy17/BoostDTC3.jpg

[Boost]

I am looking in GM Service Information for general info on what would typically set the P0299. I was hoping that the diagnostic flow chart would include some kind of voltage values but it does not.

[Boost]

Sure, my pleasure. We all learn in the process. Is this a LBZ or LMM (info probably the same anyway)? A Turbocharger Learn is something that needs to be performed to prevent a possible P0299 from setting after TC vane position control solenoid valve replacement, TC vane position sensor replacement, ECM replacement, TC replacement, Any service that disturbs the TC components. It's done with a scan tool, not sure if the Flashscan can do it or not. But I am not sure that is your issue. And how are you converting the kPa to voltage?

[FUBAR]

LBZ. And thanks for the info. And I am not converting kPa to voltage. The only thing I got to go off of or find in the Scan Tool is what you see in the pic I posted. I wish I could find where you found "39kPa for 10 seconds" in the scan tool so I could change the "39kPa" value. Up until you told me that, it would do me no good to data log the truck for boost concerns. Since you told me a difference in 39kPa (5psi) in boost will send a flag up,
I can now data log the truck, find out where Actual boost is not meeting Desired boost levels by 39kPa, and correct the problem via mechanically, or tune wise. I just want to find where you found the 39kPa value so I can verify and adjust on my truck.

Thank you so much for the help!

[Boost]

No problem I really enjoy learning about all this and if it helps you out GREAT! I am not looking in the scan tool, rather I am at the dealer working and looking at the diagnostic process for the code. And the info was for an '07 LMM, I'll check in a second if there are any differences between the Classic, and also post a little more info since it seems to be helping you out a little.

[Boost]

THIS IS FOR LBZ

DTC P0299: Turbocharger Engine Underboost

Circuit/System Description
The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by turbocharger output, engine speed, accelerator pedal input, ambient air temperature, and barometric pressure (BARO). A diaphragm within the MAP pressure sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates these changes into electrical resistance. The MAP pressure sensor wiring includes 3 circuits. The engine control module (ECM) supplies a 5-volt reference circuit, and a ground on a low reference circuit. The MAP pressure sensor provides a signal voltage to the ECM , relative to pressure on the signal circuit. The ECM converts the signal voltage input to a pressure value. Under normal operation the lowest pressure that can exist in the intake manifold is equal to the BARO. This occurs when the vehicle is operated at idle or when the ignition is on while the engine is off. The highest manifold pressures occur when the turbocharger output is high. Manifold pressure can range from 58 kPa (8 psi) when pressures are low to more than 240 kPa (34 psi) when pressures are high, depending on the BARO. The MAP pressure sensor has a range of 33 kPa (4 psi) to 255 kPa (36 psi). The ECM monitors the MAP sensor, by comparing a calculated predicted value at a predetermined engine load and speed, to the actual input.

Conditions for Running the DTC
• DTC P2564 or P2565 is not set.

• The engine speed is between 800-3,000 RPM.

• DTC P0299 runs continuously when the above conditions are met.

Conditions for Setting the DTC
The measured MAP pressure is more than 39 kPa below the expected range for 10 seconds.

Action Taken When the DTC Sets
• DTC P0299 is a Type A DTC.

• The driver information center, if equipped, may display a message.

• The ECM commands reduced engine power.

Conditions for Clearing the MIL/DTC
DTC P0299 is a Type A DTC.

Diagnostic Aids
A MAP sensor that is stuck at BARO, or is 40 kPa lower than desired while under boost, will cause this DTC to set. Use a scan tool and compare the MAP Sensor parameters to a known good vehicle. Operate both vehicles under various conditions.

Circuit/System Verification
•Verify that DTCs P003A, P0045, P0698, P0699, P2563, P2564 or P2565 are not set.
⇒ If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

•Verify the integrity of the entire air induction and turbocharger pipes and hoses by inspecting for the following conditions:
• Any damaged components

• Loose or improper installation

• Wet or restricted air filter

• Exhaust leaks before the turbocharger

• Exhaust restrictions after the turbocharger

• In cold climates, inspect for snow or ice build-up at the air cleaner, MAF sensor, and MAP sensor.

•Engine running, use a scan tool to command the TC Vane Pos. Ctrl. Solenoid ON.
•Perform a snapshot of the engine data while slowly increasing the engine speed to 1,700 RPM, and then back to idle. Refer to Scan Tool Snapshot Procedure .
•Plot the snapshot and verify that the MAP sensor parameter increases smoothly as the engine speed is increased and decreased smoothly as the engine speed is returned to idle.
⇒ If the MAP parameter plot slope is not a straight line with even RPM change, replace the MAP sensor.

•Engine running, observe the DTC information with a scan tool. DTC P0299 should not set.
•Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
•Test the charge air cooler for leaks. Refer to Charge Air Cooler Diagnosis .
•Test the turbocharger oil supply feed. Refer to Turbocharger Lack of Oil Supply .
•Inspect the turbocharger oil supply tube for restrictions.
⇒ If a restriction is found, clean or replace the oil supply tube as necessary.

•Inspect the turbocharger for debris, worn impeller and turbine blades, or damage Refer to Turbocharger Cleaning and Inspection .
⇒ If worn or damaged turbocharger blades or vanes are found, replace the turbocharger assembly.

⇒ If the charge air cooler system, the turbocharger and oil supply test normal, replace the MAP sensor.

Repair Instructions
If any service has been performed on the turbocharger or on the turbocharger components, a turbocharger relearn must be performed. Failure to perform the turbocharger learn procedure may cause this DTC to set. Refer to Turbocharger Learn .

• Manifold Absolute Pressure Sensor Replacement

• Turbocharger Vane Position Sensor Replacement

Repair Verification
Engine running, observe the scan tool MAP Sensor and Engine Speed parameter while commanding the TC Vane Pos. Ctrl. Solenoid ON with a scan tool.

• Take a snapshot of the engine data while slowly increasing the engine speed to 1,700 RPM, and then back to idle.

• Plot the snapshot and verify that the MAP sensor parameter increases smoothly as the engine speed is increased and decreased smoothly as the engine speed is returned to idle.

[FUBAR]

Holy canolies! Well, I guess I asked for it! Very much appreciated. That would explain why you couldn't figure out why I was saying "voltage" and you were finding "pressure." Two different tools. Kinda figured something like that. Now that I know that, I can stop chasing my tail and start being productive.

That said, here's my plan. Giving your info, I can start by first intiating the precedure for diagnosing a MAP sensor. Although I don't speculate that because the code is not chronic. What I'm gonna do is as closely as I can replicate the conditions when the DTC set, and data log it. On the Scan Tool on EFI, I can compare Desired Boost and Actual boost and find where there is the gap. If a DTC sets, I'll know exactly where and what the conditions were. If the DTC does not set, I still can get a feel if there is any major differences and go from there. If it looks as if the turbocharger is constanlty falling short of desired boost constantly, I can start to look for mechanical insufficies such as air filter, I/C plumbing leaks, etc...

If I can compare Actual Boost Pressure to Boost Pressure sensor voltage, I can get a feel for "x" amount of volts translates to "x" amount of boost. Although it will not be entirely accuracte due Actual Boost Pressure is spit out by the ECM by interpreting input signals from such as MAP, BARO, etc.. from what you listed and generates Actual Boost Pressure. If I can roughly estimate 1 volt is equal to 5psi boost, I can tell the Scan Tool that 10 seconds of of "x" amount of voltage has to occur under minumum voltage before P0299 is set. I don't think EFI Scan tool is capable of changing that 39kPa or 5psi or whatever voltage that translates into so, it looks as if the best thing that can be done is to recalibrate the "Under Boost Error time" to maximum amount and scale back the boost tables if the truck is incapable to keep up with the ECM demands. Could maybe this be a possibilty EFI Team???

That of course being said if there are no mechanical insufficies. I don't think thats the case since the DTC didn't set untill the truck was towing with a different tune demanding more boost. Although the tune was very mild and has not had any problems with many other identical trucks. Maybe mechanical aspects weren't able to keep up with the demands? Time will tell soons as I am able to log all this.

And it sure is great to have a tool such as EFI to be capable of doing all this!

[Boost]

Sounds great good luck and keep us posted. Seems like you have at least a logical path figured out. When I first became a tech and discovered EFILive, I felt like I gained superpowers, and when I left to Audi for a while I still had my software but I had to come back because being surrounded by supported vehicles is sooo nice and goes hand in hand with what I am trying to do.

[FUBAR]

I hear you! I spent all last night setting up my Scan Tool to monitor all the appropriate PID's and go from there. Although the truck hit a deer and is in the body shop now and won't get my hands on it till at least next Tue. Oh well, I'll post my findings when I do.

[Boost]

:( looking down at the screen, were we? you tuners are destroying the earth! :) if not with your pollution, then running down Bambi directly! :) hope all is well and you get it fixed :(

[FUBAR]

Lol! That sounded bad. I was setting it up at home last night and it's actually my Fathers LBZ, ( I'm waiting for the Cummins release for my truck) and he hit a deer last weekend and it's going into the body shop today. I as gonna data log it tomorrow but no dice.

That sounded bad, but funny though. And thanks.

[FUBAR]

Just an update, the truck has had no underboost codes after raising the underboost DTC time limit. I have not yet been able to record data from the MAF sensor with new intake to compare it to the data recorded with stock intake. It seemed as MAF lagged a bit, then when it jumped up, boost raised accordingly. I want to see if that pattern (lag) changed with new intake.

[bballer182]

rather than messing with the DTC's i would look more at the tuning. That is whats causing the problem... unless the charger is actually bad. You probably have too great of a discrepancy in the desired vane position and desired boost tables. those tables go hand-and-hand...

[FUBAR]

See, that's what I thought. Turbo vanes weren't being allowed to close enough to hit target boost. But after hearing dozens of other trucks with identical setup and tune not getting the code; is why I started looking else where. BUT still, every truck is different in someway and you very well could be right.

[Boost]

Interesting, keep us posted. Did it just happen one random time?

[FUBAR]

No, it happened a few times till I raised the error boost time to 11 min. Couldn't get it to do it data logging though, before raising the error time.

[Boost]

I just raised the error time for overboost on a friend's truck by a little bit. It sure is awesome having 'Live to do all this (first one to use that abbreviation! lol) :)

[FUBAR]

Lol...I like that! And I know what you mean. I'm really diggin' (yea, i just took it back to the 80's lol) it for my Cummins too.