MAF Sensor Issues...

[c.morewood]

Right, So I'm wondering if this is not just a MAF issue but maybe an ECU issue? I drove to work this morning K light on as usual down on power wouldnt rev over 3K. I drove home light on down on power but I kept the speed on going up the hill and although down on power she revved over 3K all the way home it was the same. But the light reamains on and the same pressure coherence fault remains.
Ive put a few pics of the Lexia pages below. correct me if I'm wrong, but it seems that the ECU thinks the car is idling when the engine is switched off?

[c.morewood]

And the latest.. I discovered that even though the K light stays on the engine comes out of limp mode when operating temperature is reached???

[jgra1]

HI Chris.. my 110 has a suspect dodgy maf.. sometimes the light is on and power is useless.. then after warming slightly power is ok to 3000 then when fully warm power is all back to normal.. in this last scenario, a restart will also extinguish the serve light.. but most of the time the light is on even when full.power is back
Always the anti pollution is the screen error

[c.morewood]

Thanks, Glad to know I'm not the only one.. I guess I'll bite the bullet as today is payday and get a new one. fingers crossed.

[RichardW]

Chris

I wouldn't fork out for a new MAF just yet - you've tried more than one to no effect, so it doesn't appear to be that. More of the issue would appear to be that it is reading 1250mbar in the inlet when the engine is not running, whereas it is probably expecting to see a number similar to the atm pressure. I can't remember where the turbo pressure sensor is, but I think I would be looking there first. If you Lexia it with the engine running, what does the manifold pressure do? Does it climb as the load (and therefore boost) comes on?

[c.morewood]

I've got to weld the de-cap for the next few days Richard Family are up so no time for diagnosis.. As long as she's hot she's working fine and she'll be staying hot for the next couple of days .. lots of running around to do. Next update 27th or 28th.. Merry Christmas everyone

[myglaren]

Gave mine a squirt of carb cleaner this morning, just been out in it and full boost is restored

[c.morewood]

Just to tie this thread up. I think cleaning the egr allowed it to remain open and caused the
"I have an engine K light on, in limp mode, with a lexia fault of
Permanent Fault inlet manifold pressure sensor coherence with atmospheric pressure. " in the oil from egr thread. I haven't had this fault for 4 weeks and the EGR sems to have cleared and seems to be opening and closing with the vaccum again. but there's still new black tarry stuff around the EGR... and still the mystery of the ecu seeing the engine running when its not.

[c.morewood]

Well the fault is back again.. I bought a new MAF just to make sure and the fault went away.. thought I'd fixed it.. but I had to disturb it again to re replace the gearbox engine mount.. and now its permanant and won't clear. So I cut the wires to the connection and spliced in another connector.. I was convinced that there was a faulty wire.. I went back about 9 inches into the wiring loom as well .. but still a permanant fault.
Is there another sensor which could be causing this fault? I've swapped 3 MAFs and get exactly the same fault with almost exactly the same pressures and indicating airflow through the sensor when the engine is stopped!!!

She seems to be down on power compared to my 35k Xantia.. exactly the same except blue and a tenth of the miles of the silver.
If The blue has 110bhp then the silver with its "10%box" is only about 70-80bhp but has more low end grunt than the blue and will happily sit at 30mph in town in 5th gear the blue needs to be about 35-40 before its comfortable.

[c.morewood]

Latest: The Lexia indicates that at least part of the ecu thinks the engine is idling all the way up to 3 or 4K rpm.. but the throttle shows movement..same problem as before up to 2900rpm when cold and dissapears when the engine is warm but the faults and light remain.

[c.morewood]

Could it be the vaccum system,or egr?
I had no power this morning even with engine warm..id established that the egr moves with my fingers. That it holds positive pressure but leaks under vaccum. I swapped the electrovalve which resulted in the above no power. This morning I swapped vaccum pipes and connections on the electrovalves and instantly revving over 3k was restored. But still the k light and reduced power.

Is there anywhere else that the pressure is measured, other than the maf and turbo? Where does the ecu get its engine rotation information from?
There has to be a sensor us somewhere and probably a replacement egr as well.
I'd welcome any further thoughts.

[c.morewood]

And yet another discovery today after driving 200 miles to Inverness and back.. just between Corgarff and the Lecht on the steepest road known to man, with 4 on board, the ecu decided it was only going to give about 50 bhp and limit engine revs to 2950.. that was an interesting journey.. however I decided to pull over and swap electrovalves again, but something made me try just pulling the electrical connectors to them and then re connecting them.. that worked, and reset some of the power and the engine revved freely again.