ALH Low Power - NOT limp mode

I've been struggling with extremely low power on a 2000 NB ALH automatic. It's a low mileage car, just barely over 100k, starts and sounds just beautiful. However it has extremely low power. I've done all the usual, VGT is free, N75 is good, 700 mg/st mass air flow full throttle, actual boost follows specified boost very nicely, boosts to 2050 mbar. Coolant temps are good, everything just looks right, but there is something limiting injection quantity to a hard limit of 25mg/st, no more, no less. All limiters are at 51mg/st after boost comes up,theres nothing I can see in VCDS that's in the way at 25mg/st. What could be going on?

What's your IQ reading? Have you adjusted the IQ with vagcom or hammer mod?

How old is the fuel filter

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Brand new fuel filter, IQ is right around 3.2

Is the field set at 32768?
Is your soft coding 1

Have you pulled the sender out of the tank to see if it's stopped up?

Do you have traction control? Forgive me I'm not very well versed in autos...

Have you done an auto scan with vagcom? You might have a code that don't trip a CEL...my door lock did that and now my interior lights work all the time

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Have you changed the oil? Does it look unusually clean? Reason I ask is I have run across several ALHs over the years that had injectors messed up and not moving enough fuel. Cars ran fine otherwise, just lethargic power delivery, way underfueling. The injectors (nozzles) were the culprit. But what I found out on two of them is that they were underfueling so much the oil never got black. Had the injectors rebuilt with new nozzles, and they ran great and the oil was black within a couple minutes.

I've seen that too, but this one is in the computer, it literally hits a limit at 25 mg/st and won't command any more fuel. It should fuel to around 48 mg/st IIRC. Anyone have any ideas what I should log and willing to look at the logs?

Intake clogged.

Try unplugging your MAF
I thought the MAF should read more than that at full potato.
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Clogged intake

Sounds like the exact same problem I had with my 03. Pull the EGR off and take a look inside.....you’ll know immediately of you have a logged intake which is all too common!

ShaferDiesel said:

I've seen that too, but this one is in the computer,,,,,,,,,,,,,,,,,,,,,,

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Maybe, maybe not. If the intake is clogged it won't get the air it needs to increase the fuel. Or that condition Oilhammer mentioned.

Did you check measurement groups 008,9 for torque limit requests? Also check 02 auto box for ratio sanity and/or perform a driving test.

I am having a similar problem and i am somewhat ignorant when it comes to numbers on my Vag Com. My Iq and everything is stock. But my car isnt reaching desired boost until about 2500 rpm. Almost like the car isnt making sufficient vaccum. I checked mechanical fuel timing and it is dead on. Is there any other ideas you guys have?

Bmangdog said:

I am having a similar problem and i am somewhat ignorant when it comes to numbers on my Vag Com. My Iq and everything is stock. But my car isnt reaching desired boost until about 2500 rpm. Almost like the car isnt making sufficient vaccum. I checked mechanical fuel timing and it is dead on. Is there any other ideas you guys have?

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Did you check how much vacuum it is producing?

How much boost is it producing?

Check if the vacuum is getting to the actuator on the turbo & how much.

Use a vacuum pump to make sure the actuator holds vacuum and the arm going into the turbo starts to move at 3 inches (or so) vacuum and max at 19 inches (or so)

The arm should also move smoothly.

Op sounds like you have a clogged intake, or a shutter valve that's not moving fully due to carbon build up.

Bmangdog said:

I am having a similar problem and i am somewhat ignorant when it comes to numbers on my Vag Com. My Iq and everything is stock. But my car isnt reaching desired boost until about 2500 rpm. Almost like the car isnt making sufficient vaccum. I checked mechanical fuel timing and it is dead on. Is there any other ideas you guys have?

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Bmandog, there is a lot of work to do to figure out what to do.
Check intake for clogging and actuator for movement as well as vacuum and the maf.
Could be one, or more of those possibilities.
Usually is, unplug the maf and see if it changes.

N75 actuator control valve is a likely culprit as well, but that's vacuum.

I've checked for vacum from N75 to the actuator and it holds 25 in/hg no problem. Vacum pump is producing 28 in/mg at idle as well. Intake is perfectly clean as well. I have checked whole fuel system from in tank to IP. I have deleted snow screen, New fuel filter, New air filter, Verified IQ is perfect. I have data logged and sent to kerma TDI to look over, etc etc.

Have you done an auto scan yet?

And have you tried driving with the MAF unplugged?

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WildChild80 said:

Have you done an auto scan yet?

And have you tried driving with the MAF unplugged?

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I’ve tried the maf unplugged and it’s worse, no auto scan yet.

Ran an auto scan, everything is perfect

Unplug the maf

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Run a boost log and post it here through the Malone website graph.
https://www.malonetuning.com




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