MAF Testing

[tonytiger 0]

Is there a way to test the MAF self-clean feature when it's not on the car?

Is it just a case of connecting some pins to earth and 12v?

 

Also, how can I test this feature for a MAF that is on the car? Does it only work after the engine has been started, or is it every time the ignition is switched on then off?

 

I understand that I should be able to see the wire glow for a couple of seconds during the clean cycle - is this correct?

 

Thanks,

Tony.

[Supercharged 2]

Not sure the best way to test but what I do know is that the Hot-wire type MAF's can be damaged by K&N filter oil (if an old filter is cleaned and too much new oil applied) and also that some badly fitted alarms can case the clean not to activate after the engine is switched off...

[Storm 0]

What are the symptoms of a failed MAF?

[fla 9]

Just to resurrect this post, I'd be interested in testing the MAF as well as systoms of failure. I was told the cutting out problem may be due to the MAF being faulty?

[dr_mat 0]

"the cutting out problem" - which cutting out problem?

The MAF is easy enough to test .. with the right equipment. But what makes you think the MAF has anything to do with stalling? Stalling is more likely to be an idling problem, and the MAF has nothing to do with idling.

[fla 9]

"the cutting out problem" - which cutting out problem?

The MAF is easy enough to test .. with the right equipment. But what makes you think the MAF has anything to do with stalling? Stalling is more likely to be an idling problem, and the MAF has nothing to do with idling.

The cutting put problem has been referred to in a few of my previous posts. Having had the car inspected by an auto electrician he said that the MAF sensor was not at its best (dont know how he diagnosed that one) and the Crank sensor needed either to be replaced or removal and a good clean of the earthing contact on the engine block, which I'll try first.

His thoughts on the stalling were that these two were the key suspects. ISV etc is all ok, in fact verything else is ok (for the moment!) Hence my question. And when dr_mat, you say "the right equipment" what does that include?

[Kevin Bacon 5]

You can only test MAFs thoroughly on an Oscilliscope to monitor the waveform.... but even that is inconclusive, so say my local Bosch place are sick of the things. It's not just VRs that suffer with MAFs, nearly all cars that use them do.

 

And it does affect the idle. Whilst the MAF's range is acceptable, the ECU is constantly using it to fine tune the fuelling. If it bypasses it use the TPS for fuelling, it's going to be a bit too rich when you step off the gas and the ISV will struggle to catch it.

 

They're fickle things! But that doesn't bother me. What does bother me is why VW charge Corrado owners £378+VAT for a MAF when Golf Highlines and MK4s/Beetles etc get them for £78+VAT exchange. W@nkers.

[dr_mat 0]

Someone (RW1?) wrote up a huge post on the "VR stall issue" a while back saying that a lot of the time it's an ECU basic settings issue. If the ECU is setup properly for the car and it's sensors, it doesn't happen.

If some bits are changed and they don't do the right things, then it's possible that this can happen. Or it's possible that the old calibration will be OK and the ECU will be fine. Bit of a lottery.

It all seems to come down to the fact that the ECU calibrates lots of things off against each other - so if the original baseline is way out, it will never work right, no matter that the RELATIVE calibration of all the sensors to each other will work out ok in most circumstances.

[dr_mat 0]

(IIRC the reduced price for the Golfs and Beetles was because of a MAF reliability issue that VW identified with those particular cars. In cases like that, because they are seeing a lot of warranty replacements of the part, they drop the price, cos it lowers VW UK's total cost associated with dealing with those warranty repairs. Same with the Lupo wipers, according to Henny.)

[Kevin Bacon 5]

I've done the basic settings Mat and it makes absolutely no difference.

 

VW can't expect their customers to do the basic settings every time their battery goes flat over the weekend. And how many VAG technicians are going to bother? Or do the Basic settings access some other area of memory that the normal EPROM doesn't go near?

 

Yeah you could be right on the MAF exchange ...... I do recall Vince saying he's found the wire MAFs to be more reliable than the newer ones on the whole.....but it still grates a little knowing other VWs get them for 70 quid!

[dr_mat 0]

The newer cars with the electronic throttles do the basic setting recalibration periodically automatically I believe.

Didn't someone find genuine recon MAFs available from the US for about $130 a while back?

[Kevin Bacon 5]

Yeah they're lucky! Although drive-by-wire feels odd to me. You think OBD1 VRs have flat spots, try a MK4 DBW!!

The pedal's artificial weighting is too heavy imo....starts aching your ankle after a couple hundred miles.

[fla 9]

Just for the record, i removed the MAF and gave it a bit of a spray with carb cleaner, left it to dry and reinstalled. So far there's not been any problem, but it looked spotless and the wire was clean and unbroken. I've also removed the Crank sensor and given that a clean too. Again clean but the block was quite rusty, so i guess that may be part of teh cutting out prob. Gave that a good rub with emery and the then a spray with WD40 and, as I said above, no probs so far. I'll put the CPS comments on my "cutting out" thread for anyone else with a similsr problem.

[RW1 0]

I've done the basic settings Mat and it makes absolutely no difference.

 

Not all Corrado give a visible/physical change, must be to do with sensor tolerances, you're not the first to have a Corrado to react like this! Even on cars that do change, it's nothing to write home about, its quite subtle.

 

VW can't expect their customers to do the basic settings every time their battery goes flat over the weekend. And how many VAG technicians are going to bother?

 

You should know! Typical stealers! They just abandon the customers when the going gets a little difficult than taking a spark plug out and emptying the oil.

 

Most VW technicians just don't know, lack of proper training and every VW model being different, even variants of the same model. Corrado has 6 different set ups on post 1992 cars alone depending on the engine. So I suppose it ain't surprising when you multiply that number of differences by the number of models over the last 15 years. You have to be an anorak as the Basic Settings technicques are hidden away in the VAG manuals for each model.

 

Or do the Basic settings access some other area of memory that the normal EPROM doesn't go near?

 

No, in the case of the Corrado OBD1, it puts the ECU into an offset mode to do the assessment of all it's sensor inputs.

 

Oh, one last thing. Change any of the sensors, ECU temp, Throttle Position, Lambda Probe, MAF. Always do a Basic Settings afterwards with a fully warmed up engine (+12mins from start-up). As said before... somewhere, it's what makes the VR6 silky smooth to drive.

 

The newer cars with the electronic throttles do the basic setting recalibration periodically automatically

 

Hmmm, thats a new one but I've not studied the 2005 models yet.

[RW1 0]

Is there a way to test the MAF self-clean feature when it's not on the car?

Is it just a case of connecting some pins to earth and 12v?

 

PM me with your chassis number so I know which circuit diagram to look at. Testing can be done on the car.