TD5 Fluctuating boost under load

Yes, I have ran it with the boost solenoid bypassed. It only made a max of about 12psi, and still same symptoms.

Can't be sticky waste gate, as I get no over boost, 15psi solid. Just drops off under acceleration.

How about with unplugged MAF? is it the same?

Have not tried that. Can give it ago tho.

That would be relevant to rule out the MAF

I had thought about it, but I've been monitoring the MAF values over the last few days and they seem good.

Will give it a shot anyway.

there are moments in that log where the MAF fails suddenly on quite constant boost drop with cruise controll on and if it happened on horizontal road not while descending then it's a problem with the reading

Here is a dump from the nanaocom, Wide Open Throttle to around 120Kph, just before the end, under light load, a small amount of acceleration is applied, and the boost falls off and comes back on as per the original fault.

there is also a dump with the AFM removed! Holly hell, its like a train!!!

No signs of the boost related problem, and, it will make upto 20psi under acceration!!!

Iv never seen a disco perform like that!!!!!! NO Signs of the fault at all, however, that doesnt prove anything really, perhaps having it disconnected is masking another problem???

I reckon there's a good chance it's the MAF then. I've seen something similar, where the MAF seems to get readings that are ok via the Nanocom, but runs much better with it unplugged. New MAF, problem goes away. I've found MAFs do need to be replaced from time to time, and the one cheap, aftermarket MAF I bought was no better than the old stuffed original.

Buy a new MAF, and worst case, you have a spare one for future problem solving.

it proves exactly what i expected;) .. to not write again : http://www.aulro.com/afvb/2306596-post18.html :)

Great result!

Now the debate on which MAF to buy.