Thread: Td5 Engine Surging

Philip is on the money...

There are 2 possibles:

Either as above the MAF is going out of range...
Or
The boost is high enough that you are pulling beyond the MAF sensors range.

Likely option 1

Originally Posted by Tombie

Philip is on the money...

There are 2 possibles:

Either as above the MAF is going out of range...
Or
The boost is high enough that you are pulling beyond the MAF sensors range.

Likely option 1

Mike, did you get the files I sent you last night?

Originally Posted by Tombie

Philip is on the money...

There are 2 possibles:

Either as above the MAF is going out of range...
Or
The boost is high enough that you are pulling beyond the MAF sensors range.

Likely option 1

Mike,


I'm thinking MAF.


I have not changed by boost settings - what could cause the boost to suddenly go beyond the MAF sensor's range?

I have not changed by boost settings - what could cause
the boost to suddenly go beyond the MAF sensor's range?

It's not the boost it's the MAF.
Most fail by reading low some fail reading high.
Regards Philip A

Originally Posted by PhilipA

It's not the boost it's the MAF.
Most fail by reading low some fail reading high.
Regards Philip A

OK, I think I see.


I was going by Mike's 2 options whereby I understood one as being a problem with the MAF or the boost being beyond the MAF sensors range (implying that there is too much boost being produced?)

If your boost is stock this should not happen although I suppose it is possible if the wastegate is jammed shut. Have you checked that the wastegate opens by physically opening it and also pressurising the actuator (a little bit) to see that the diaphragm is OK?
The MAF does not measure boost, it measures the mass of air being used by the engine. It is before the turbo in the air inlet.
Regards Philip A

IMO option 2 from Tombie's last post is not neglectable at all, cos watching very carefully the readings we'can see that first time when according to the throttle track 1 reading(and the others) you floored it the MAP went up to 217(i'll "round" the readings to be easyer) and second time again close to 217 and both times the MAF was around 670...but the AAP reading shows that it was serious suction there as it dropped from 101 to 95/96

if we extract the AAP from MAP both times the boost is around 1.2(120KPa) Bar and based on the infos from "LUCAS Td5 Diagnostic" in Nanocom files the maximum MAP allowed by the overboost protection is 210 for Defender and 230 for D2 considering the AAP 100 so you are very at the limit...and as we know we can consider a 10% margin in these cases

now based on the fact that it's a serious suction there it's possible that the MAF's circuit has some limiter too and when it reaches the 5V to cut the feed... i'm up to open one and make some measurements there in the near future

i saw this kind of happenings on several forums and not just for D2, that's why the market is full of all kind of MAF enhancers/limiters, here is a not very old thread from this forum DIY Map/Maf enhancer / manipulator ... i'm not gonna go deeper into this to not be named idiot again but it'a something to think about in case the new MAF will not fix things...or to find the reason why that huge suction under load.... by the way did you replace the depression controll valve?

That's a fantastic summation Fery...