Xsara Picasso 2.0hdi MAF sensor problems.

[Ianhw77k]

The wife's car has decided to go into "almost limp home mode", as I like to call it. Basically there's no power in the upper rev range, struggling to get to 20mph on some hills, more on faster roads with a run-up.
One of my neighbours has a rather nifty diagnostics tool, a copy of the Delphi version. He plugged it in and it showed a problem with the MAF sensor. This was changed a couple of years ago and the replacement was a Siemens one so you'd think it would last. Anyway, I bought another one, it arrived while I was out and my wife had a go at fitting it herself. She didn't get the plug plugged in all the way so I rectified this and my kind neighbour plugged his diagnostics tool in again and cleared the code.
The trouble is, this has made no difference. I've spent around £60 on the part so we're not very happy about it.
Any ideas about where to check next? It definitely feels like some sort of electronic problem. When the weather improves I'll see if I can get my neighbour to check it again. The EGR valve seems to be working, the engine sounds pretty normal, just no power.
When the wife tried to drive to work on Friday morning she said it had got worse, almost no power and a bit of smoke but I've yet to see that for myself. She ended up turning round and coming home and I had to give her a lift.

Also, I'm trying to test the resistance across the wires on the MAF sensors, does anyone know which pins to check?

[GiveMeABreak]

Hate to say it, but this is often the case replacing parts without a proper diagnostic - which will be hard to do without a Lexia, as these generic code readers can't read all the ECUs or perform advanced testing. As there are many ECUs talking to each other and the BSI - it is quite common for an error code to appear in one area, as a result of a problem in another area. You have to eliminate the suspected causes one by one and you can only really do this by running a full diagnostic with a Lexia, otherwise it gets expensive and may not solve the issue.

If you post up your VIN so we can see exactly what vehicle you have, we can determine the emissions control system on the vehicle for a start and this might help others with some pointers.

[Ianhw77k]

OK. I'll get it when the weather calms down. This diagnostic tool seemed pretty good, he was controlling the fan and the EGR valve with it and it seemed to know its way around the car. It did say there was an EGR problem as well but he seemed to think this was only because of the MAF sensor problem. The symptoms certainly seem very similar to what happened before when the MAF was faulty.
What I'd really like to do is shut the EGR off and disconnect it completely. They seem to cause more trouble than they're worth.

[GiveMeABreak]

Ok, that will help - I suspect there is a high possibility that the EGR system is blocked - how many miles has it done?

[Ianhw77k]

It's around 180,000 miles but the egr valve was replaced a couple of years ago when we had the first MAF sensor problems. I also got them to do the cam belt as well, the whole lot came in at over £900.
If I've got this right, the vin number is:

VF7**************[VIN obfuscated, can be read by forum staff]
39020484

[Ianhw77k]

OK, just been having a fiddle with it. I think there's a clip missing on the accelerator cable. There's a lot of play there and the outer part is moving around. I've set it as tight as it'll go (there's still some play) and put a jubilee clip around the outer to hold it in place. Problem appears to be solved.
This doesn't explain why the diagnostics were showing a MAF sensor problem and I've probably just wasted £60 that we can ill afford but at least it seems to be working.
I'll order a new cable this week, I expect it's still on the original one. Going to attempt driving to the supermarket now, we'll see how it goes.

[RichardW]

Can the Delphi tool get live data on the air flow. IIRC it should be around 400 at idle, and it should jump up if you disconnect the vac pipe to the EGR solenoid. The EGR on these is vac controlled, but there is no feed back on position - the solenoid can be doing the right thing, but the valve may be stuck open.

[Ianhw77k]

That's interesting as he seemed to think he could control the egr valve with his machine. I would have thought if it was vacuum operated, you'd need the engine running and we had the engine off.

Anyway, we seem to be having some new problems, I'll keep them in this thread as I think they're related.
So, I fixed the accelerator cable but then we seemed to be getting a flat spot on acceleration at around one quarter - one third travel. I suspected a bit of a worn potentiometer so we ordered a second hand one. The wife fitted it today but the problem persists, it was also pumping out more black smoke than usual.

I put some additive (2 stroke oil) in the fuel and too it for a good thrash around the country lanes this evening. The smoke seems to have improved but the flat spot remains. It's going to be a bit tricky in town traffic, if you get stuck on the flat spot for too long, you have to push the accelerator quite far down to get off it, then it races away at full boost!

She's got an exam tomorrow which she can't afford to miss, I just hope it gets her there.