VCDS shows Too lean on block 32 (partial) at 11% fuel trim

[movingdirt]

Thanks for the help

[movingdirt]

Thanks

[movingdirt]

thanks

[Okedokey]

Checking Fuel Pressure
Prerequisites:
Ignition ON
Engine ON (Idle)
System voltage at least 11.0 V.
Coolant Temperature at least 80 °C

[Select]
[01 - Engine]
[Meas. Blocks - 08]
Group 103
[Go!]
Field 1: Fuel Pressure (Low), Specification: 2800...7200 mbar
Field 2: Fuel Pump Adaptation, Specification: -1000...+1000 %
Note:
Timing chain driven engines such as the CCTA, CBFA and CCTA were phased in during model year 2008. Those engines do not use a G410 (Low) Fuel Pressure Sensor so Measuring Blocks group 103 is not applicable.

Group 106
[Go!]
Field 2: Fuel Rail,Pressure (actual): 55% or below is normal at idle
55% to 60% is a gray area, it may be okay, but may indicate a problem
Above 60% implies there is a failure or restriction
Causes of low pressure can include kinks or restrictions in fuel lines
Fuel filter issues including restricted/clogged or incorrect part number
Failing lift pump in fuel tank. We have seen numerous cases of sub-standard quality "factory" replacements in "factory boxes" that were obtained from aftermarket sources and are not sourced from official dealers. This led to troubleshooting problems that were solved by installing correct factory parts. We encourage customers to only install lift pump and fuel filter sourced directly from a VW/Audi dealer.

http://wiki.ross-tech.com/wiki/index...BWA)#Fuel_Pump

[movingdirt]

thanks

[MrBigglesworth]

Hi there

I've got a similar sounding issue, so I'll chime in with my details so far in case it helps you.

So my LTFT are around 0% +/- 1% on idle, but in the 10.9%-14.8% range on throttle (so 10.9% is more or a summer percentage and after long distance runs, and 14.8% is winter and after lots of short runs), my high pressure fuelling is very spot on vs request, but low pressure fuelling is very good vs request, my Low pressure duty cycle sits around 62% on idle with engine warm, my engine boosts well, i do have the very occasional misfire (across cylinders, erratic).

Things that I have done changed, all which didn't really impact:

- new plugs (on a service when I got it 2nd hand) and PCV (old one was shot and caused a couple of oil leaks, replaced under used car warranty)
- carbon clean and HP sensor (as the manifold was off it was easy and cheap to change)
- cleaned throttle body and adapted
- checked turbo intake pipe for leaks - nothing
- did a boost leak test (even though a leak past the turbo would actually cause a lean on idle/rich on throttle which is not what the symptoms are) and I seemed to have air leaking past the turbo oil seals.
- new fuel filter
- new MAF
- new O2 sensor (picked up genuine new for cheap so thought why not)
- new n80 as this can affect fueling

And none of the above has really made much of a difference (engine a touch smoother and responsive for all the new bits and the carbon clean).

Things I have run through my mind that could be done:
Fuelling side: PRV, LP sensor, LP pump, rechecked for hose restrictions, changed injectors. But I don't really think I have a fuelling issue as my fuelling hits request so this shouldn't be causing knock on effect. Also on the LP pump, I've read that wiki linked above, but others also say that it's only above 70% that you need to change these pumps over. Also as I don't get regular misfires on one cylinder I don't think it's an injector issue.
Air supply side: MAP sensor (I did pull my old one and it looked decent condition and is only 5 years old anyway.
Ignition side: As misifres are quite erratic, don't think I have a coil pack problem.
Exhaust side: I need to retest for leaks. This is my prime suspect to check out further after a mapper has directed me to it. He asked that i drive around with the MAF unplugged to see if the LTFT changed. I think the expectation was that it shouldn't change but mine actually rose to >18% (at which point I stopped). He thought that an exhaust leak could cause this.

Frustrating as the car drives really well. Most people tell me to forget about it, but I don't like not sorting problems if I know about them; then again don't want to waste money chasing it (so far I have actually spent pretty little as recouped quite a bit of $$ selling old sensors which were actually working fine and getting the new ones cost effectively from a dealer stock clearout).


I also know of someone else with the 2.0T engine who again had a LTFT idle on spec and partial/throttle at around 18%-25%, kept triggering his EML. He changed MAF and O2 and PCV. He says after the first two he was still getting EML, but then after the PCV it stopped, however, I think his codes were only properly reset in VCDS after the PCV so not 100% sure what fixed it!

[MrBigglesworth]

Also, if you could post your logs on some runs (general as well as WOT) of HP actual and request, LP actual and request, boost, misfire count,MAF and RPM - I would be interested to compare. I could do likewise.

[movingdirt]

thanks