Thread: TD5 Fluctuating boost under load

Originally Posted by PhilipA

The one with mossies is the MAF ( Mass Air Flow) sensor. The one in the inlet manifold is the MAP ( Manifold Absolute Pressure)sensor.
Regards Philip A

Yes, sorry, my bad.

MAF looked good, bit of dust/grime inside but nothing that I would think to be a problem. Hot wire looked good and in tact.

MAP/IAT sensor was all gunked up with carbon, so I gave that a hit with the degreaser and toothbrush and all looks good now.

I will endeavour to find my SD card and get some solid data from the Nanocom in the next few days.

Would be very interesting to hear the results of your MAP cleaning?

Cheers Jerry

Don't know that it achieved much Jerry. Nothing noticeable.

Got some data on the way to work tonight, a drop in air flow from the MAF coincides with what I'm seeing on the boost gauge, which is a drop in boost pressure.

The more I think about it, it could be fuel related... Injector harness??? I would of thought unlikely???

OK, Managed to grab some data on the way to work yesty arvo, having a dig back through it, there are a few little discrepencies, like where the coolant temp jumps to 1800 odd degrees...

not sure whats going on there, need a keen and knowing eye to cast over it.

Those two coolant temp and fuel temp episodes were short nanocom glitches, i saw this kind of things many times without being relevant...as you can see it's just for a glimmer

some questions:
1. Did you experience the symptom while that list was recorded?
2. Did you set cruise controll in this time? cos that's how it looks
3. Was the road climbing before the end of the log... or during the drive?

there are some noticeable issues there but i must have the answers to figure it out

Yes, it happened twice during this recording, first; normal driving, second whilst under cruise control.

And the log ends with a slight incline and a decrease to 80kph.

It's visible on the file when it happens too... from all i see there i'd put a new genuine MAF cos there are some strange fluctuations... unless the trip was on a very variable climbing/descending path....before that did you rule out the sticking wastegate, cos that must be 100% certain

the best would be a recording from a plain path if it's possible, by the way did you try to drive it with the MAF unplugged and see how it goes?

Just for something different, have you checked your wastegate control? You can get surges in boost if one of the hoses comes astray. If the wasteage isn't working properly, and you get overboost, then the engine will cut fuel in order to reduce the boost.