Thread: So I purchased a cheapie

So don't worry about the dots.

In the bottom right corner of the screenshot is a little box with "MAF AM" and "MAP AM" written in it - AM meaning AIRMASS (or AIRCHARGE). That is a direct reading from the td5 ecu on how much air is in the cylinder. MAF reading is from the MAF, Using mass air flow, and MAP reading is from the MAP/IAT sensor in the inlet manifold using the speed density method.

For this application both methods are fairly accurate.

As you can see in the average air charge figures, the cheap MAF is reading somewhat lower than the MAP.

What this means is that because the ecu uses aircharge readings to fuel the engine, if the MAF is reading low , then the ecu will reduce the fuel injected, if the MAF is reading high, it will inject more fuel than it should, messing up the air fuel ratios, and possibly blowing smoke.

Having an under reading MAF then has a cascade effect on the driveability, as the auto trans ecu (EAT) will read higher throttle input required for current performance, and this will adversely effect gear changes, shift points, and the ability to lock up.

Many have noted that a failing MAF produces these issues, unfortunately due to the often gradualistic nature of MAF deterioration, you might not even realise that the car is not like it used to be.

Next issue with the cheap MAF I had was repeatability, I decided to re-do the curve so it read accurately, I actually got it really really close.

Next morning was cool,hop in the car, start up and immediately the MAF is reading wrong again. What happened?

Well it seems that the temperature calibration side of the unit is itself faulty, and this is not fixable by the end user.

So the cheap MAF I had is completely unusable.

Hope this helps, any questions please ask!

I'll get back when I can.

Cheers
James

Sorry if that was a bit long winded, it can difficult to understand at first!

Originally Posted by shack

So don't worry about the dots.

In the bottom right corner of the screenshot is a little box with "MAF AM" and "MAP AM" written in it - AM meaning AIRMASS (or AIRCHARGE). That is a direct reading from the td5 ecu on how much air is in the cylinder. MAF reading is from the MAF, Using mass air flow, and MAP reading is from the MAP/IAT sensor in the inlet manifold using the speed density method.

For this application both methods are fairly accurate.

As you can see in the average air charge figures, the cheap MAF is reading somewhat lower than the MAP.

What this means is that because the ecu uses aircharge readings to fuel the engine, if the MAF is reading low , then the ecu will reduce the fuel injected, if the MAF is reading high, it will inject more fuel than it should, messing up the air fuel ratios, and possibly blowing smoke.

Having an under reading MAF then has a cascade effect on the driveability, as the auto trans ecu (EAT) will read higher throttle input required for current performance, and this will adversely effect gear changes, shift points, and the ability to lock up.

Many have noted that a failing MAF produces these issues, unfortunately due to the often gradualistic nature of MAF deterioration, you might not even realise that the car is not like it used to be.

Next issue with the cheap MAF I had was repeatability, I decided to re-do the curve so it read accurately, I actually got it really really close.

Next morning was cool,hop in the car, start up and immediately the MAF is reading wrong again. What happened?

Well it seems that the temperature calibration side of the unit is itself faulty, and this is not fixable by the end user.

So the cheap MAF I had is completely unusable.

Hope this helps, any questions please ask!

I'll get back when I can.

Cheers
James

I understand what you have written, but am unable to correlate it to the graph. I'l blow it up and try again.

Question. I have decided to make the injector harness a service item. Given what you say about sensor degradation, would you put these sensors in that same category?

Another question. What turbo upgrade would you suggest for a slightly chipped D2 for better driveability with off road improvements?

Originally Posted by Tins

I understand what you have written, but am unable to correlate it to the graph. I'l blow it up and try again.

Question. I have decided to make the injector harness a service item. Given what you say about sensor degradation, would you put these sensors in that same category?

Another question. What turbo upgrade would you suggest for a slightly chipped D2 for better driveability with off road improvements?

Just look at the little box bottom right, it's got the averages there.

Sorry, which sensor?

For a slightly modded or even a bit more - tune, it's hard to go past the hybrid core that many here have used, I've had one pumping considerable figures for quite some time, and when you consider it's about the same price as a second hand one on aus..speaks for itself.

Cheers

Originally Posted by shack

Sorry, which sensor?

MAF, MAP.

Originally Posted by shack

and when you consider it's about the same price as a second hand one on aus..speaks for itself.

Cheers

Cheers. I put a hybrid in my 300 TDi and was well pleased.

Originally Posted by Tins

MAF, MAP.

Do you have a Nanocom? Check what readings you are getting, or post a log and I or someone can check them, as to whether it's worth replacing old ones before they fail, that's up to you and the finance department! If they fail they won't leave you stranded.

If upgrading turbo, you can upgrade the MAP/IAT as well and get more performance if desired, if you don't want more performance but need to replace it, and you are happy to get someone to re calibrate it, you might as will get an uprated one, then you have options later.