It's driving me MAF - er mad! Please Help

[bytecode]

Hi again guys - I really need some soothing words today!

I had to replace my original MAF 6 months ago after sucking up excessive rainwater leading to the dreaded "Anti Pollution fault"

Then I had the same problem again - loads of rain - "Anti Pollution fault" - IML light on.
I tried swapping back to the original MAF - which seemed happy - IML light went out - everything seemed fine - until over a few weeks - gradual loss of power and economy - and then one day - clouds of black smoke, but no IML light.

I checked the fault code with PP2000 - I got:

• Intermittent fault. Air flowmeter signal. Air flow too low coherence.
• Permanent fault. Air flowmeter signal. Open circuit or short circuit toe earth.

I ordered a 2nd hand original MAF from a breaker - who assured me that it was in good working order.
I fitted it, cleared the fault codes and went for a five mile drive - MUCH better - no smoke, not quite as much pull as I was hoping for - but I figured that it'd take a while for the exhaust to clear out all of that accumulated soot.
I checked for any fault codes - there were none.

A couple of hours later - I went for a drive to the next village for some shopping - less than one mile into my journey - no power, loads of smoke, "Anti Pollution Fault" and IML on.

I've tried reseating everything, I've read the codes:

Intermittent fault. EGR air circuit fault. Airflow measured less than recommended.

• ECU fault code - P0401m
• engine speed - 2313 rpm
• airflow setting - 747 mg/impulse
• EGR Solenoid valve OCR - 0%
• intake air flow - 259 mg/impulse
• actual delivery - 28 mm3/stroke

• Do I really need to buy yet another MAF?
• Is there likely to be another fault that could be killing MAF's on my car?

Any thoughts/advice gratefully received!

[bytecode]

Well, I've just gotten back from a 55mile round trip to the nearest city with a motor factors (Plymouth), where I shelled out for a brand new MAF, which I then fitted. The journey there was horrendous - climbing hills in 2nd gear at 20 MPH bellowing smoke.

After fitting the MAF, the IML light went out - Hurrah - but the performance of the car was no different.
Then, on the way home, about 15 miles after fitting the MAF, the IML light came on and the "Anti Pollution Fault" message was back.

It's taken 3 hours to travel less than 55 miles, cost a fortune in fuel and I've shelled out £85 for an OEM part that has done nothing to resolve the problem - other than allowing me to rule out the MAF itself as the basis of the problem.

All I can think now is that it must be a wiring issue?
Could there be a bad earth or are some of the five wires that come out of the six pin multi plug broken internally?

I'm going to have another code reading session whilst I drink my beer and try to persuade my girlfriend not to burst into tears.

[keppler]

You could just have eliminated the maf sensor by driving with it unplugged.
As regards the bellowing black smoke and serious loss of power, these symptoms remind me of a time when my car had an egr valve stuck open. Try disconnecting the vacuum pipe to the egr and plugging it with a bit of duct tape then take the car for a spin. IF this still doesn't sort the problem then try removing the egr valve itself and blanking it with a piece of metal cut from a beer can or biscuit tin or something, as it could be just coked up inside with soot and jammed in an open position. I'm not saying this is definitely what the problem is but its the area I would look at first.

[bytecode]

Hi Keppler,
thank you for taking the time to respond.

The problem with disconnecting the MAF is that I don't know what kind of behaviour/result to expect with it unplugged.

When I got home I did another PP2000 scan and now have the following codes:

• Permanent fault. Fault. Pre/Post heating relay circuit. Relay stuck - I omitted listing this one in my first post as I thought it irrelevant to this problem.
• Intermittent fault. Intake air temperature signal. Open circuit or short circuit to earth. Flow too low.
• Intermittent fault. Air flowmeter signal. Air flow too low coherence.
• Intermittent fault. EGR Air circuit fault. Airflow measured less than recommended

The EGR one is a "new" one.

I'll take a look at the EGR tomorrow, but I really REALLY hope that it's not an issue with the EGR - given that I blanked it off with a piece of beer-can metal 18 months ago - if there's any through put then surely that must mean that the metal has blown through or something.

Does anyone have any further thoughts with these new codes?

[crackpotterpig]

The symptoms do sound like a egr issue, if you have removed the egr valve make sure you have blanked the vacumn pipe from the control valve on the bulkhead.
The fault codes air intake temperature and air flow meter signal do indicate a maf issue, but as you say it could be a wiring issue.If your careful you can clean the maf with carb cleaner.

[bytecode]

Hi crackpotterpig,

I haven't removed the egr valve, I merely inserted a blanking plate in place of the metal gasket where it mates with the air intake on the flywheel side of the engine. I've just checked the integrity of the blanking plate and I'm relieved to find that it's still intact and appears to be blocking the EGR quite happily, as it has done for the 18 months or so.

I'm absolutely stumped.

The only thing that I can think of doing next is to somehow wire up the MAF without the plug and then insert pins into the loom further along, thus bypassing the part of the wires where they bend and enter the 6 way plug.

Does anyone have any other ideas?

[rwb]

EGR definitely blanked is good.

Is the air filter clean and intake free? Could the airflow actually be too low, or is the problem definitely electrical?

Black smoke suggests there isn't enough air for the amount of fuel injected, so too little air sounds like the most plausible problem (the other is too much fuel, but that makes no sense to me).

Have you tried running with the MAF disconnected? In this case it will get no signal rather than a possibly incorrect signal. The question is: is there any difference? If so then what?


The glow plug thing does need sorting out. They run for about 5 minutes after starting the HDi, even though the light doesn't come on.

[Captain Jack]

I ran with a knackered glow plug relay for years with no issues.

Can't offer advice on your problem though. Have you checked the obvious, like split hoses or poor wiring connections?

[bytecode]

Hi CaptainJack,

yeah - I'm not too worried about the glow plug relay at the moment, as I understand it, this is a common and chronic fault on these cars.
Mine started with little trouble during winter, it just took say, quarter of a second longer than normal on the chilliest days.

I'm hoping that I can get past the latest problem - stupidly disconnecting the battery - yielding an "Engine Immobiliser Fault"
viewtopic.php?f=3&t=20144#p200791 so that I can test whether cleaning the earth strap points helps at all. If not, I have another MAF ready to which I have soldered some wires directly to the socket pins, with dress making pins soldered at the other end - to insert directly into the relevant wire of the MAF harness - thus bypassing the MAF 6-way plug.

There's very little "hose" on a HDI 2.0 90, as there's no intercooler, but I can't hear any whistling.

[crackpotterpig]

try running it without the maf plugged in you will get the eml on but wont hurt to test run it that way you are eliminating the maf and associated wiring,if with it unplugged it makes a differenc ie, reduces black smoke and drives better i would go for a replacement maf.

[keppler]

Hi Keppler,

The problem with disconnecting the MAF is that I don't know what kind of behaviour/result to expect with it unplugged.

• Permanent fault. Fault. Pre/Post heating relay circuit. Relay stuck - I omitted listing this one in my first post as I thought it irrelevant to this problem.
• Intermittent fault. Intake air temperature signal. Open circuit or short circuit to earth. Flow too low.
• Intermittent fault. Air flowmeter signal. Air flow too low coherence.
• Intermittent fault. EGR Air circuit fault. Airflow measured less than recommended

The EGR one is a "new" one.

I'll take a look at the EGR tomorrow, but I really REALLY hope that it's not an issue with the EGR - given that I blanked it off with a piece of beer-can metal 18 months ago - if there's any through put then surely that must mean that the metal has blown through or something.

Does anyone have any further thoughts with these new codes?

Your ecu is able to measure the egr flow through the maf sensor so in theory if you blocked the flow several months ago then that fault should not be a new one?
As somebody said here already the glow plug relay shouldn't be a problem. Except on the coldest of days maybe.
Here's what I would do, begin by erasing all of the faults stored on the ecu. Then unplug the maf and take the car for a spin. Do not worry about the effects of unplugging it. Plenty of people have done it here before and when I did it, the engine management light didn't even come on. I drove my car 'unplugged' for two months before replacing mine.
If the maf is at fault what you should get is an almost perfect return to normal driving.
You say you cannot hear the turbo spin up. To me this is worrying. I'm not too familiar with the 90bhp layout as mine is a 110 but you need to find the pipe that goes from the compressor of the turbo to the intake of the engine. then squeeze it and get someone to rev it up to 3krpm, the pipe should expand quite strongly. If not then the turbo is not working properly or possibly, not being allowed to spin up (This is why you need to check the maf sensor first) Also give the pipe a good look over for holes/ splits while you're there.

[keppler]

Hi Keppler,

The problem with disconnecting the MAF is that I don't know what kind of behaviour/result to expect with it unplugged.

• Permanent fault. Fault. Pre/Post heating relay circuit. Relay stuck - I omitted listing this one in my first post as I thought it irrelevant to this problem.
• Intermittent fault. Intake air temperature signal. Open circuit or short circuit to earth. Flow too low.
• Intermittent fault. Air flowmeter signal. Air flow too low coherence.
• Intermittent fault. EGR Air circuit fault. Airflow measured less than recommended

The EGR one is a "new" one.

I'll take a look at the EGR tomorrow, but I really REALLY hope that it's not an issue with the EGR - given that I blanked it off with a piece of beer-can metal 18 months ago - if there's any through put then surely that must mean that the metal has blown through or something.

Does anyone have any further thoughts with these new codes?

Your ecu is able to measure the egr flow through the maf sensor so in theory if you blocked the flow several months ago then that fault should not be a new one?
As somebody said here already the glow plug relay shouldn't be a problem. Except on the coldest of days maybe.
Here's what I would do, begin by erasing all of the faults stored on the ecu. Then unplug the maf and take the car for a spin. Do not worry about the effects of unplugging it. Plenty of people have done it here before and when I did it, the engine management light didn't even come on. I drove my car 'unplugged' for two months before replacing mine.
If the maf is at fault what you should get is an almost perfect return to normal driving.
You say you cannot hear the turbo spin up. To me this is worrying. I'm not too familiar with the 90bhp layout as mine is a 110 but you need to find the pipe that goes from the compressor of the turbo to the intake of the engine. then squeeze it and get someone to rev it up to 3krpm, the pipe should expand quite strongly. If not then the turbo is not working properly or possibly, not being allowed to spin up (This is why you need to check the maf sensor first) Also give the pipe a good look over for holes/ splits while you're there.

[bytecode]

Hi Keppler,

Sadly I'm unable to do any testing at the moment as I have the "Engine Immobiliser Fault", So I'm unable to start the engine.
I don't have the four character PIN card. I tried texting and emailing the www.carkeycodes.co.uk for a quote for the PIN - but I guess they're enjoying the bank holiday as they haven't replied yet.

It looks like I'll have to pay Peugeot Dealer for the privilege of the PIN.
I'm amazed that the car will go into immobilised mode just because the battery is disconnected - surely that'd mean that you have to re-associate the keys anytime that you have to replace the battery or do any of the work on the car where manuals state that you should disconnect the negative cable?

I've always found that driving without the MAF plugged in results in rotten performance - but that may be that I test it when there's a problem.

Like I say, the blanking plate has been on for about 18 months - the EGR air circuit fault only appeared on Saturday afternoon.

I'll try the tests once I've managed to get the PIN from somewhere so that I can actually start the car.

Thank you for your suggestions.

[bytecode]

£24 lighter in the pocket for my PIN from Peugeot, I've now de-immobilised the car with PP2000 and can start testing it again.
I took it for a 2-3 mile run with the Antipollution fault and engine management light on and some smoke, but it felt like it wanted to pull again, unlike the last time that I drove it.
I stopped the engine, waited a minute, started it again, and the antipollution fault notice has gone and the engine management light is off.
I also noticed that I can hear the turbo in the background - so I'm assured that it appears to be functioning to some degree.

I don't know whether this is an ongoing symptom of an intermittent problem or whether the car is recovering now that I've cleaned all of the earth points, put the £85 MAF sensor on and fiddled around a bit or what. We shall see.

I'll test it properly later.

Thank you all for your suggestions so far.
I can hear the I'll test it properly later.

[bytecode]

So after the earlier elation of the car feeling much better on the short test - the car is struggling again.
I've cleared the faults, taken it for an (attempted) run - it takes ages to crawl up to 2000, 3000 revs in 2nd gear, it wont exceed approx. 31000 RPM, the quantity of black smoke is horrendous.

The only fault (aside from the stuck pre/post heating relay) is the "Air flowmeter signal. Air flow too low coherence." one - what does that mean - does anyone know?
The turbo pressure at 3128 rpm was 988mbars - surely the turbo pressure should be higher than atmospheric pressure at that RPM?

I couldn't hear the turbo at all during this test, compared to the short stint of joy at lunchtime - so could it be a dirty, manky turbo in need of a clean?