Thread: td5...overboost, no guts and i'm at a loss

lol - very true. I've just checked the nanocom csv file and it's actually in that! I used the column header as the label.

They might need to update their software.

thanks for the replies all.
the maf was replaced with an original one

if it was the MAF i thought i would have an error logged?

Have you checked the supply voltage and resistance/continuity in the wiring from ECU to the MAF?

don't want to sound like a dummie, but not sure how to do that. might need to take it into auto electricians?

So it's looking like a MAF problem, either sensor itself or wiring.

i will check wiring tomorrow for anything obvious.

Thanks again all...so glad i got the nanocom!!

Pete,

In my experience a faulty MAF doesn't always throw a fault but has given me the exact symptoms you report - drove me mad.

If you know someone else with a TD5 then try swapping the MAFs around and logging the readings at idle, that low reading is a dead giveaway. That will help narrow down where the fault lies. For what it's worth, I have had new MAFs that never worked properly.

Hope you get it sorted,

Ian.

Thanks for that Ian, i will check the wiring loom today as a first step then if all else fails a new MAF.
your help has been much appreciated.

will post how i went

cheers
Pete

Originally Posted by mools

BTW Stallie, units for air flow are m3/hr, don't think you'd get far with grams

Kg/Hr not m^3/hr. It's measuring Mass Air Flow rather than Volume Air Flow.

The graphing I'm messing above uses the internal calculations used by the ECU to process the MAF and MAP/IAT into the volume of air filling a single cylinder on each intake cycle.

The ECU will use the MAF generated value in virtually all circumstances. When the MAF value is below 4000 the MAP/IAT values are used as a substitute. I came across a mention of another engine management system using this technique to work around poor MAF performance at low air flows.

The two calculated values should be close to each other because they are measuring the same parameter in two ways. When you unplug the MAF to see if the engine runs better, you are forcing the ECU to use the value derived from the MAP/IAT rather than the one from the MAF.

For the MAP/IAT the Excel calculation is:

=ROUND((MAP*100*14432040)/(ROUND(CONVERT(IAT,"C","K")*10,0)*8134),0)

and for the MAF

=ROUND((MAF*333330)/(RPM*5),0)

You'll obviously need to alter the MAP, IAT, MAF and RPM to point to the correct columns.

cheers
Paul

Originally Posted by Pepi

thanks for the replies all.
the maf was replaced with an original one

if it was the MAF i thought i would have an error logged?

don't want to sound like a dummie, but not sure how to do that. might need to take it into auto electricians?

So it's looking like a MAF problem, either sensor itself or wiring.

i will check wiring tomorrow for anything obvious.

Thanks again all...so glad i got the nanocom!!

You should be able to check with a multimeter and a copy the wiring diagram and electrical library from RAVE. I've attached a couple of pages that will help.

This is the description from RAVE:

Input/Output
The MAF sensor receives battery voltage from the main relay in the engine compartment fuse box. Signal output from the MAF sensor to the ECM is a variable voltage proportional to air drawn into the engine.

Input to the MAF sensor is via pin 5 of connector C0570 at the engine compartment fuse box. This 12 volt supply is provided by the main relay via fuse 2 in the engine compartment fuse box. The MAF sensor receives the input voltage at pin 3 of the sensor connector.

Output from the MAF sensor is measured at pin 11 of the ECM connector C0158. The earth path is via pin 20 of the ECM connector C0158.

So you should be able to measure 12V (or battery voltage) between pin 1 and 3 on the MAF plug.

It would be worthwhile measuring the resistance between pin 2 on the MAF and pin 11 of C0158 to make sure the wiring isn't damaged in some way.

The connector views attached show the pinouts looking into to the connector.

cheers
Paul

Thanks again Paul for your help and knowledge.
I disconnected the maf this morning, on the way to work
the car was running smoother but it did surge several times.
Is this expected as there is no maf connected or does it point
to a secondary problem?
Cheers
Pete

Originally Posted by Pepi

Thanks again Paul for your help and knowledge.
I disconnected the maf this morning, on the way to work
the car was running smoother but it did surge several times.
Is this expected as there is no maf connected or does it point
to a secondary problem?
Cheers
Pete

It would suggest you have other problems. It would be worth doing a recording with the MAF unplugged and see if you can capture the surging.

cheers
Paul