Freelander 1 2004 Facelift TD4 - Error Code P0100 MAF short circuit

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Tannaton

Active Member
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Location
Beverley, East Yorkshire, UK
Evening all...

So the Hawkeye Total arrived today :)

To recap - have a Facelift Freelander TD4 Commercial bought as a project. Starts and ticks over just fine, but hold it at say 2,300 rpm it misfires a bit with smoke and diesel smell.

Has error code P0100 - Mass Airflow Sensor Short Circuit or Open Load

*But* if I go into engine live data with the engine running - it reads 514 mg/strk for the airflow and this changes if you blip the throttle.

Is this a "ECU Calculated" value in the absence of a working sensor?

Any comments appreciated.
 
MAF READINGS M47 TD4 FREELANDER & R40


Well if you want to carry out the conversions the T4 settings at idle should be around 480 milligrams per stroke and at 3000 rpm 675 milligrams.

These are the only settings you should need and the engine temp should be around 88C, the readings will vary slightly from car to car

You need to hold the car at 3000 RPM for about 10 seconds, and then let it return to idle.

The lower reading will be around 325mg/stroke at this point, and then return to 480 mg/stroke once the EGR closes again.

The EGR should close within 5-10 seconds at which point you should notice a slight but perceptible change in the engine note.

Hope this helps, your reading seems a little high, therefore I would clean out the manifold and the MAP sensor and recheck if you have not done so already, maybe also unplug the MAF and squirt a little electrical contact cleaner into the loom socket plug it on & off a few times just to make sure the contacts are ok.
 
Arctic2 said:
MAF READINGS M47 TD4 FREELANDER & R40


Well if you want to carry out the conversions the T4 settings at idle should be around 480 milligrams per stroke and at 3000 rpm 675 milligrams.

These are the only settings you should need and the engine temp should be around 88C, the readings will vary slightly from car to car

You need to hold the car at 3000 RPM for about 10 seconds, and then let it return to idle.

The lower reading will be around 325mg/stroke at this point, and then return to 480 mg/stroke once the EGR closes again.

The EGR should close within 5-10 seconds at which point you should notice a slight but perceptible change in the engine note.

Hope this helps, your reading seems a little high, therefore I would clean out the manifold and the MAP sensor and recheck if you have not done so already, maybe also unplug the MAF and squirt a little electrical contact cleaner into the loom socket plug it on & off a few times just to make sure the contacts are ok.
Click to expand...

Thanks Arctic2 - that it most useful and appreciated. FYI I am used to using diagnostics at a detailed level to diagnose and fix diesel engines but the majority of my experience is with Volvo cars using their VIDA system - so whilst I know the basic principles, I'm learning with the Hawkeye system and Land Rover/BMW systems. I've obtained a copy of Rave but am struggling to find baseline values for things such as MAF and Fuel Pressure at idle etc. so any pointers to any such info would be greatly appreciated.

This particular vehicle I think has been a challenge for it's previous owner for some time - it has at least 2 new injectors (brand new), a new MAF (but pattern part) and a EGR bypass fitted. When I bought it the car had been de-cat'd which I assume was because it became clogged.

At the weekend I did a partial strip down and clean up - changed oil and all filters, cleaned the inlet manifold and replaced the thermostat. I also took out the fuel pressure regulator and cleaned it as I've seen these cause similar problems in the past when they are contaminated.

Thanks Again...
 
Tannaton said:
Evening all...

So the Hawkeye Total arrived today :)

To recap - have a Facelift Freelander TD4 Commercial bought as a project. Starts and ticks over just fine, but hold it at say 2,300 rpm it misfires a bit with smoke and diesel smell.

Has error code P0100 - Mass Airflow Sensor Short Circuit or Open Load

*But* if I go into engine live data with the engine running - it reads 514 mg/strk for the airflow and this changes if you blip the throttle.

Is this a "ECU Calculated" value in the absence of a working sensor?

Any comments appreciated.
Click to expand...

If the EDC can't get an actual air flow reading from the MAF. It will substitute a value based on engine Rpm and boost pressure. As your MAF is showing a fault code, I suspect that the value you are seeing, is the calculated value, rather than the measured value.
 
Nodge68 said:
If the EDC can't get an actual air flow reading from the MAF. It will substitute a value based on engine Rpm and boost pressure. As your MAF is showing a fault code, I suspect that the value you are seeing, is the calculated value, rather than the measured value.
Click to expand...

That's my thinking too... I've ordered another MAF to try and I will go with GrumpyGel's suggestion and disconnect it so see if it changes the values at idle. If I still get the error then I guess it's multimeter out time to check wiring back to the ECU. It is recording the inlet air temperature okay which I gather is also a sensor on the MAF.
 
UPDATE: Tonight I installed a new (well second hand from e-bay) genuine BOSCH MAF and I have now been able to clear the fault. That's good news as it would imply that I don't have a wiring fault.

However - when I read live data the MAF reading is now circa 2,000 - 2,100 mg/strk - this doesn't seem right compared to the advice given previously (it's 4x that). I've I hold the revs at 3,000 rpm it increases to around 2,400. Given that it is measured in mg/strk should it stay around the same for all rpm (assuming no boost pressure) ?

And I'm still getting lots of smoke and misfiring at 2,200 rpm. FYI fuel pressure at idle is around 27,000kpa.

Any comments appreciated...
 
Tannaton said:
UPDATE: Tonight I installed a new (well second hand from e-bay) genuine BOSCH MAF and I have now been able to clear the fault. That's good news as it would imply that I don't have a wiring fault.

However - when I read live data the MAF reading is now circa 2,000 - 2,100 mg/strk - this doesn't seem right compared to the advice given previously (it's 4x that). I've I hold the revs at 3,000 rpm it increases to around 2,400. Given that it is measured in mg/strk should it stay around the same for all rpm (assuming no boost pressure) ?

And I'm still getting lots of smoke and misfiring at 2,200 rpm. FYI fuel pressure at idle is around 27,000kpa.

Any comments appreciated...
Click to expand...

I'd expect to see a figure of around 500 milligrams per stroke. The mass of air at 20°C being 1.293 Kg per cubic metre. This works out at 645 milligrams per 500cc cylinder stroke. I'd expect to see 450 to 550 measured, off boost. Obviously as the induction system is boosted, the air mass will increase. However the boost is only twice atmospheric pressure, so air mass measured shouldn't get as high 2000 milligrams per stroke. This would suggest the replacement MAF is faulty.
 
Nodge68 said:
I'd expect to see a figure of around 500 milligrams per stroke. The mass of air at 20°C being 1.293 Kg per cubic metre. This works out at 645 milligrams per 500cc cylinder stroke. I'd expect to see 450 to 550 measured, off boost. Obviously as the induction system is boosted, the air mass will increase. However the boost is only twice atmospheric pressure, so air mass measured shouldn't get as high 2000 milligrams per stroke. This would suggest the replacement MAF is faulty.
Click to expand...

Thanks - makes sense - I've ordered another MAF.
 
Your MAF reading suggests that the second hand MAF is no good, I hate to say this but buy cheap by twice, here are a couple of photo's of the MAF reading when the engine temp is not fully up, as you can see totally different from yours, also I have added a couple of videos, hopefully they may help ?



 

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Tannaton said:
Evening all...

So the Hawkeye Total arrived today :)

To recap - have a Facelift Freelander TD4 Commercial bought as a project. Starts and ticks over just fine, but hold it at say 2,300 rpm it misfires a bit with smoke and diesel smell.

Has error code P0100 - Mass Airflow Sensor Short Circuit or Open Load

*But* if I go into engine live data with the engine running - it reads 514 mg/strk for the airflow and this changes if you blip the throttle.

Is this a "ECU Calculated" value in the absence of a working sensor?

my freelander was doing the excact same and engine light was on turned out to be fuel pump in rear wheel arch changed filter while I was there and was good as new now no more misfire or smoke

Any comments appreciated.
Click to expand...
 
Update: I've tried two more MAF's - one genuine Bosch but second hand, one new pattern part - and the same result - a MAF reading of 2,000+ at idle. That's three MAF's recording the same.... confusing. Does anyone know the pin wiring for the MAF, is it possible to use a multimeter to check the reading back to the ECU?

I'm just wondering if I have a wiring issue somewhere or there is one of these cheap tuning boxes secreted somewhere that fiddles the reading?

Thank you for the videos Arctic2 - they were very helpful. I do agree 100% if you buy cheap you buy twice - if this was my daily driver I would have bought new but it's a weekend project I acquired whilst drinking and bidding on e-bay, so funds are limited...

Just another question - is the engine roughness and fuel comp figures for each cylinder calculated by the ECU?
 
I'm thinking that there could be a box of tricks to fudge the EDC onto thinking that more air is entering the MAF, than is actually the case.
 
Just an update... not solved this yet as been bizzy with Christmas, problems with the wife’s car, doing tax return now and a few other tasks inconsiderately eating into my weekends... however will get back to it maybe this weekend coming or next.

To recap, engine smoking and misfiring around 2200 - 2500 rpm. Hawkeye grossly over reading the MAF value when working (but calculates the correct value when MAF disconnected) (have tried 2 MAFs).

I have had a look for a tuning box but can’t see anything obvious. I have removed and refitted the ECU - connections look fine.

My next steps will be to check the MAF wiring physically and with a multimeter. I have also made a couple of blanking nuts for both the injector and fuel rail so I can isolate the fuel supply to each injector individually to see if one of them is leaking (will do a leak back test first tho).

I will sort this...... somehow. Thank you all for your help and on going interest - it is appreciated.
 
Should say I have no idea about these things, just being nosey really :)

If there is a tuning box in the system - it must be a pretty poor one! Trying to play around with idle doesn't sound like a very sensible thing to do to me.

With all these different MAFs showing the wrong but consistent value it would indicate the wiring has an issue or possibly the ECU itself - ie the Pin in for the MAF reading. Difficult job to try another ECU though as you'll need the CCU swapped over as well and possibly the immobiler ECU (something leads me to believe its separate to the CCU on TD4?). Not sure if the MAF feed is a variable voltage or pulse - if its pulse you're going to need an oscilloscope presumably. Reading Rave on my L Series, I know some of the ECU signals are voltage and others pulse.

However, the ECU does appear to recognise correctly when the MAF is disconnected. The engine should run OK with the MAF disconnected - therefore if the misfiring is still occurring, it would indicate that the problem is not related to the MAF.
 
Nodge68 said:
Just a thought. Is the EGR valve bypassed?
Click to expand...

Yes it has an EGR blank fitted. Unusually there is no sign of the exhaust gas pipe, the last few I'd looked at the old exhaust gas pipe is usually attached to the side of the EGR blank - on this one it is missing... I will trace it back at some point out of curiosity to see what's been done to it.

I think this car has had this problem for a while, it seems to have had a lot of work, there is at least 1 new injector, there was a new but cheap pattern MAF fitted (which was not working), EGR bypass and it had been de-cat'd which I assume was because the original became clogged (maybe wrong). I've since replaced the exhaust and Cat.
 
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