P38A DSE autobox - ideas please. It was going too well.... SOLVED

Mukiwa said:

Block the EGR using a 1p coin, that makes a difference as well. I'm happy with it for a 2.5 ton car

Click to expand...

No need for that, unplugging the pipe does the same thing and it can easily be refitted for the MOT. It's actually 2.25 tonne

Datatek said:

The cheap ones are NBG and £400 is way too much. Have you though of a second hand one from a breaker? They don't often fail so second hand is not a bad bet. Is your EGR disabled? If not pull the vacuum pipe off the EGR valve at the manifold and plug the rubber pipe with a screw.

Click to expand...

I can get second hand - I just needed to hear that they don't fail very often. Cheers for the info

Datatek said:

No need for that, unplugging the pipe does the same thing and it can easily be refitted for the MOT. It's actually 2.25 tonne

Click to expand...

Well I won't split the difference over 1/4 tonne And I didn't know that about that EGR pipe, only about putting a penny in the pipe

The MAF sensor has nothing to do with how the engine runs. But if totally duff it can cause the ECU to become confused and misinterpret air conditions..

wammers said:

The MAF sensor has nothing to do with how the engine runs. But if totally duff it can cause the ECU to become confused and misinterpret air conditions..

Click to expand...

Well there's a contradiction in terms. "Nothing to do with how the engine runs but can confuse the ECU" (and thus affect how the engine runs)

Datatek said:

Well there's a contradiction in terms. "Nothing to do with how the engine runs but can confuse the ECU" (and thus affect how the engine runs)

Click to expand...

If working correctly to measure amount of exhaust gas ingested when EGR is active. If duff and sending invalid signals to ECU can cause the ECU to become confused about air conditions and activate EGR at the wrong time. At least that's what BMW recon but what do they know. The runs fine when MAF is disconnected should be a clue.

Here we go again.....

'Ma, hide the china, the boys are at it again......'

Saint.V8 said:

Here we go again.....

'Ma, hide the china, the boys are at it again......'

Click to expand...

I have explained this many times, if people don't know enough to understand that is their problem not mine, i have no intention of explaining it again.

I'm happy that it runs with the MAF sensor unplugged and EGR blocked. My biggest concern is getting a replacement MAF sensor

Anyway serious question - how exactly does a MAF sensor break? Is it circuits or some auto magic inside it?

Mukiwa said:

I'm happy that it runs with the MAF sensor unplugged and EGR blocked. My biggest concern is getting a replacement MAF sensor

Anyway serious question - how exactly does a MAF sensor break? Is it circuits or some auto magic inside it?

Click to expand...

The circuits either fail or become unstable giving incorrect readings. The idea of the MAF sensor on an EGR diesel is that for any given engine speed manifold pressure there is a flow rate through it. The ECU knows this flow rate but when EGR is active that flow rate reduces. The reduction in flow represents the amount of exhaust gas being ingested. The ECU then modulates the EGR valve to control ingestion and maintain a combustible air to fuel ratio to give clean combustion suitable for the throttle demand power setting.

Ok got that Wammer's, thanks. So why with a MAF sensor failure does the engine lose power? Is it going into "limp home mode" for safety?

Mukiwa said:

Ok got that Wammer's, thanks. So why with a MAF sensor failure does the engine lose power? Is it going into "limp home mode" for safety?

Click to expand...

As said the ECU becomes confused. Ask BMW that's what they say.

Roger that. Cheers, it most certainly was confused!

The MAF sensor has nothing to do with how the engine runs.

wammers said:

If working correctly to measure amount of exhaust gas ingested when EGR is active. If duff and sending invalid signals to ECU can cause the ECU to become confused about air conditions and activate EGR at the wrong time. At least that's what BMW recon but what do they know. The runs fine when MAF is disconnected should be a clue.

Click to expand...

You cannot have it both ways, a duff MAF can certainly affect how the engine runs by if only by causing the EGR to malfunction.
I would be interested to know why it caused the loss of power with the EGR blocked.

Speaking of MAF sensor units. I had a loss if power last evening and a reading of -38° when I plugged it into my maxicom this morning.. but it ran perfectly today offroading and on a 30 minutes round trip this evening??

Mukiwa said:

My biggest concern is getting a replacement MAF sensor

Click to expand...

The biggest concern is why are they so expensive? - if a new one was 50p you wouldn't be concerned

Are they difficult to produce/calibrate, or are they full of myrr - or possibly snake oil

RangeRoller dt said:

The biggest concern is why are they so expensive? - if a new one was 50p you wouldn't be concerned

Are they difficult to produce/calibrate, or are they full of myrr - or possibly snake oil

Click to expand...

I cracked an old one open and there us a little circuit board inside and not just a couple of wires similar to other units.
I've seen Lucas units for just less than 200€ ..I've layed nearly 400€ on my rad and spinny stuff on the front of the engine... Mine can wait for short while...

Edit that last one about Lucas .. totally wrong there... Try over around 300€... Holy "over the top pricing... My fûčkong god" batman....

Snake oil. How much Is a pcb for Christ sake

You had no luck rejuvenating it then mark?
What is 38• - water temp?

RangeRoller dt said:

Snake oil. How much Is a pcb for Christ sake

You had no luck rejuvenating it then mark?
What is 38• - water temp?

Click to expand...

That MAF was dead and I'm pretty sure the second one of a similar age is also...
-38° is the air intake temperature... It's cold here all day!! But strangely the hevac is reading 20° outside....