MAF signal all over the place, only at high rpm.

[VanCityA4Q]

I'm having some MAF issues on my 2000 1.8TQA, I'm trying to get some tuning done but my MAF signal will be smooth while driving normally but when I go to do a good pull it starts jumping all over the place once I'm in higher rpm. Is it possible that I could be overloading my stock MAF?

I've replaced it once already as well with a new Bosch sensor and still am getting the same results. I've also replaced the plug and wires all the way to the ecu with the proper shielded wire and grounded it.

[andyrew]

Stock turbo?

You shouldnt be overloading the MAF with a stock turbo.

Show us your MAF placement, I have a feeling your not getting straight enough air.

[VanCityA4Q]

Not stock at all, turbo is a turbonetics t3/t4 .63 A/R. I can watch my MAF steadily climb on my tuning software from Motoza, plus I can look at the logs after, MAF signal steadily climbs from around 60g/s @ 2450 rpm in second gear until I hit 4750 rpm and 304g /s, then it drops to 108 then 98 then 100 then 103.... I posted a couple pics of part of my logs, Column "F" is my MAF reading column B is rpm, C is throttle position.




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[VanCityA4Q]

It gets even more erratic in 3rd gear and 4th


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[Rampid]

.63 A/R turbo with a stock maf?? You needed to upgrade that thing like yesterday dude.

[andyrew]

100% this /\

You are most definitely over the limit.

Ran into the same issue.

[Dan[FN]6262]

I would recommend a B6 S4 MAF (P/N should end with a K or J), you have to convert the plug, but that's easy.

You'll have a hard time over saturating that bastard. I run one without issue. It's not even in an optimal position (vertical) with a filter attached right on the MAF.

Do not remove the mesh screens from the MAF housing.

[VanCityA4Q]

Awesome, thanks guys! I appreciate the help very much! Got an S4 MAF on order, I'll let you all know how it works out.
And yes I'm running my stock MAF in a TT225 MAF body. By mistake I guess!

[VanCityA4Q]

Could I not just run the TT225 MAF? I would think it's got a higher range than my stock one, plus i have one from when I bought the body. And the plug works from my car to it.

I guess I'll just give it a go and see what happens, no harm in trying :)


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[Dan[FN]6262]

You'll have to have the MAF sensor scaled for the housing, otherwise it'll be all fvckered. Like of you just popped your factory sensor in the larger TT225 housing. If you use the TT225 sensor and housing together, you will still have to change your tune around.

Edit: since when have bad words been starred out?! Lame.

[MetalMan]

Stock MAF in a larger MAF housing such as from a TT225 or VR6 is the way to go. Looks like Motoza set your tune up for this too.

If you're running the TT225 MAF housing, I do think you might be over-saturating your MAF sensor @ 304 g/s.
My understanding is the stock MAF sensor in stock MAF housing is good for ~220 g/s... this means in the TT225 MAF housing the stock sensor should be able to report up to ~255 g/s. Your 304 g/s is a lot higher!

My suggestion is to use a larger MAF housing. See what Dave @ Motoza suggests.

[VanCityA4Q]

Stock MAF in a larger MAF housing such as from a TT225 or VR6 is the way to go. Looks like Motoza set your tune up for this too.

If you're running the TT225 MAF housing, I do think you might be over-saturating your MAF sensor @ 304 g/s.
My understanding is the stock MAF sensor in stock MAF housing is good for ~220 g/s... this means in the TT225 MAF housing the stock sensor should be able to report up to ~255 g/s. Your 304 g/s is a lot higher!

My suggestion is to use a larger MAF housing. See what Dave @ Motoza suggests.

Dave and I have talked a lot about this issue. He's never had to deal with it before. But he also said my car has been a bit of a bastard from the get go, and I agree completely, Stupid ATW. He's also at a loss. Gonna swap in the 225 sensor tonight and go for a run, at least if it stays stable Dave can start actually tuning my car instead of helping me troubleshoot it lol

[VanCityA4Q]

You'll have to have the MAF sensor scaled for the housing, otherwise it'll be all fvckered. Like of you just popped your factory sensor in the larger TT225 housing. If you use the TT225 sensor and housing together, you will still have to change your tune around.

Edit: since when have bad words been starred out?! Lame.

I have no doubt Dave at Motoza has scaled it properly. He's done quite a few of these. My car is a bit of a beast now though :)

[nynoah]

Sorry but I hate to ask this... but just to make sure. Do you have the MAF facing the right way. If it was backwards it would do what you are describing.

[Dan[FN]6262]

I assumed you were tuning it yourself. Best just talk to Dave and do what he wants since he is tuning it. Nothing is more frustrating than someone swapping around parts while you're still figuring something out.

Does no one tune their own stuff anymore? lol

I mean, shit, even Nefmoto is freeware and as good as maestro, but is more hands on. But it's freeeeeee and no need to pay someone to tune then lol.

[Dan[FN]6262]

Sorry but I hate to ask this... but just to make sure. Do you have the MAF facing the right way. If it was backwards it would do what you are describing.

Looks like it's facing the correct direction, flange with bolt holes are facing the filter.

[Dan[FN]6262]

What are the specs on that turbonetics unit?

[VanCityA4Q]

It's a T3/T4E with an E50 compressor wheel and a F1-57 Turbine wheel with a T3 Turbine housing @ 0.63 A/R part number 10784-BB

And yes my MAF is installed with the arrows pointing the correct way.

Just tried the TT225 MAF and the signal was much better, it still had some minor fluctuations but not nearly what the stock one had.


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[Dan[FN]6262]

Nice, that'll be good for 350awhp on pump, with a daily tune