Thread: DIY Map/Maf enhancer / manipulator

IMO the differences are:
1. a good MAF is not supposed to go out of range unless the air flow is really so high which means turbocharger overspeed, so with a clamp you trick the ECM but the suction is still excessive
2. by clamping the voltage there's no more correspondence between the real air flow and the input to ECM, cos your MAF is reading high all the way untill it exceeds the threashold so the ECM doesnt get proper readings from the beginning, which it would with a perfectly working sensor... aproximately the same thing which was blamed in that thread of mine with the TPS input used as MAF.

see the graphic and you'll understand that as long as your's is exceeding 5V is not good, there must be a certain correspondence between the voltage and air flow for the management to not be mixed up.

Originally Posted by sierrafery

IMO the differences are:
1. a good MAF is not supposed to go out of range unless the air flow is really so high which means turbocharger overspeed, so with a clamp you trick the ECM but the suction is still excessive
2. by clamping the voltage there's no more correspondence between the real air flow and the input to ECM, cos your MAF is reading high all the way untill it exceeds the threashold so the ECM doesnt get proper readings from the beginning, which it would with a perfectly working sensor... aproximately the same thing which was blamed in that thread of mine with the TPS input used as MAF.

see the graphic and you'll understand that as long as your's is exceeding 5V is not good, there must be a certain correspondence between the voltage and air flow for the management to not be mixed up.

Thanks for the graph. Is it in reference to the TD5 MAF or a general explanation?

Are you asking if i know the start point is correct e.g 0V? Because if it was higher than 0 and the scale was correct it would go out of range early and also give a high reading throughout the range.
I don't think this is the case, but could check the readings against this graph if it relates directly to the TD5.

I still feel the issue is:

Originally Posted by sierrafery

1. a good MAF is not supposed to go out of range unless the air flow is really so high which means turbocharger overspeed, so with a clamp you trick the ECM but the suction is still excessive

However not necessarily turbo over speed for 2 reasons (before mod):
1. I kept turning the boost down thinking it was this even though i did not get a turbo over speed error or an over boost error.
2. With my snorkel air ram head, the air speed will be higher before the turbo anyway. I know this makes a difference as i turned the head around backwards and it helped.

The graph is general not dedicated for Td5 but according to many measurements i made it's accurate as refference, it's quite correct corroborated with many live data logs from well running engines i've seen and confirmed by the Td5 ECU's pin disposal table + the MAF's description from RAVE which all are confirming that the MAF's output is not supposed to exceed 5V.

Originally Posted by Jazzman

1. I kept turning the boost down thinking it was this even though i did not get a turbo over speed error or an over boost error.

the fact that you dont have high boost doesnt mean you cant have high suction in case there's a leak at the wastegate or somewhere within or after the turbocharger, in this case you can get "air flow high" fault code which you should with your MAF's readings and there's no fault code allocated for overspeed.

IMO you are working and eating your mind in vain as long as you cant confirm 100% that your MAF sensor is working well... that's why i'm insisting so much to rule out the sensor 100% before you make such radical mods as voltage clamps

Today I was playing around with this again. I turned the boost up to see if i would still get an over boost error with the Zener circuit in place.

I got Nanocom to display up to 1.35 bar and then it went to 0.

The error code i got was 'driver demand problem 1.'

I than disconnected the Zener circuit and did it again. Same error. This made me curious.

I than turned my boost down to 1.26 bar left the Zener circuit disconnected and went for a drive.

No surge, no errors. The car still runs fine on this boost setting, i think my boost was getting up to 1.32 bar before today. I'm not sure why reducing my boost hasn't worked before, maybe i didn't turn it down enough.

One thing i've noticed is my air flow will only reach 4.8 volts now. I didn't take notice of the nanocom MAF reading as i was too busy looking at the boost readings. However from previous tests 4.8V is about 660 kg/hr. At idle it reads 2 volts and approx. 140 kg/hr.

I'm confident my MAF is OK as these voltages are consistent with sierrafery's graph.

I guess the conclusion is my car is running fine, my boost was fractionally too high all this time.

I'm sorry all that doesn't help the rest of you much