Anyone? Any ideas?

Swop the MAF sensors around and see if the readings follow the sensor or stay the same. If the former I would try a new sensor or if the latter you will have to investigate the turbo and pipes on that bank. The EGR's will operate if blanked and are normaly open at idle. 2012 TDV8 Vogue (L322)

No worries, will try that over the weekend and report back.

Stupid question, but assuming bank 1 is drivers side (RHD), bank 2, passenger?

I found the problem!!

As suggested, I swapped the MAF sensors and went for a run, but the low Kpa kept showing on bank one, concluding that it wasn’t the issue.

This evening, I rigged up a very crude smoke machine and pumped smoke down the MAF for bank one, and lo and behold, the air duct going from the MAF pipe to the turbo was cracked. I initially thought it was the intake, the way smoke was billowing out, but after some phone and light gymnastics, I was able to get a good look at it and see what was happening. It looks like the mounting bolt was missing off it, allowing it to bounce around and crack.

Click image to enlarge

Update on this:

Over the weekend, I removed the drivers side air duct with the following steps:

1. Remove drivers side wheel
2. Remove wheel lining
3. Remove access plate behind strut
4. Remove underbody trays
5. Remove lower intercooler hose
6. Remove the metal intercooler - turbo pipe that the intercooler hose was attached too (through the access plate.
7. Now that’s all out of the way, undo the metal pipe running horizontal that is attached the air duct (can’t remember its name)
8. Unbolt the air duct and pull of the turbo, then wriggle it out the front of the car. It’s a pain, but doable.

I then got the broken piece plastic welded back on, and reinstalled. MAF values back within 10%, way more power. Seems like we’re back on top!

The only other niggle that remains is this cold / hot start strange behaviour. When I start it cold ( overnight, or after 5 hours or so) it runs beautiful. Fores on the key, power delivery smooth and instant.

Start it warm, and seems like it takes a bit longer to crank, then feels a bit more sluggish. What sensors control air/fuel maps for hot and cold? Any ideas? No codes present, all values look normal.

Cheers

Hi All,

Just wanted to update and say this problem has been solved.

As per the previous post, the initial hesitation was from the split lower air duct to driver's side turbo. I removed it and had it plastic welded, and now runs beautifully.

With the improved performance, I then noticed a distinct difference between cold/warm running - much better at cold. This has also been solved - turns out that even though my car is an 07 model and didn't throw a engine light / code when I blanked the EGRs, it was still looking for input from those sensors when the car warmed up and throwing the air/fuel ratio way out, hence the poor running when warm.

I bought the EGR patch from BAS and uploaded it via my GAP IID, and what a difference! Instant throttle, pulls like a steam train, and no hesitations. I'm very happy.

So, for anyone blanking early cars, if you notice even slight difference in your performance when the car's cold vs hot -- you might need to tune out the EGRs too, even without the engine light/ codes.

Thanks again for everyone's help.

Cheers

Well done! Satisfying result!!! Nice when you find something and it makes a big difference 2009 (2010 MY) 5.0 Supercharged Autobiography
2007 TDV8 Vogue SE
2005 BMW E63 645ci
2024 Porsche Macan

Hi Ben,

Bit of a thread revival but is your 07 still performing fine since doing the BAS EGR patch?

Also how did you deduce that the air/fuel ratio was out?

Many thanks