Mass Air Flow Signal Error

[Mistermorgan]

Hi again!

I had an issue in the last week where the throttle goes completely unresponsive and blips in and out followed by EML staying on.
I initially thought my EVC was failing so disconnected it but it continued after a scan with the foxwell I'm getting Mass air flow sensor signal error once cleared car is fine again but seems to come back when the car is hot. I say hot because I have an iBUS android unit and it shows me engine is warm no issue but after maybe another 5/10 minutes of driving it will start.

So far I have cleaned the MAF with some MAF sensor cleaner, pulled the DME, did actually see some oxidization on a few of the pins so used some contact cleaner (none of the pins with oxidization were related to the MAF just to add)

Went ahead and started testing the cabling my understanding of the situation is below

DME Connector X60003
Pin 1 - Type E (input) - Signal hot Film air mass meter -> Maf Sensor Pin 5 (continuity OK)
Pin 3 - Type E (input) - Signal hot film air mass meter -> Maf sensor Pin 1 (continuity OK)
Pin 4 - Type A (output) - 5V Supply -> MAF sensor Pin 4 (continuity OK)

Testing with engine running and MAF disconnected
MAF sensor Pin 4 =5v
MAF sensor Pin 2 = ~14v
this is when grounded to MAF sensor Pin 3

From this I am just seeing there is nothing wrong with with the voltage supply from DME - does anyone know how I test the signal output from the MAF to DME is there a way to test or a range I should be seeing?
With foxwell connected and engine running I am getting reading from MAF sensor but I havent had it connected and reading this whilst the error has thrown only at idle on the driveway

Does all of the above just suggest the MAF needs replacing?

If I've learned anything from this forum its to test before throwing parts at things ahah!

thanks as always for any support here

[80stech]

You did some good work with the testing and the MAF is a known trouble spot so I would replace it. One more thing you could try is rapping on the MAF with your knuckle or tapping with a hammer handle to see if it stalls the engine out. Also driving with it unplugged might help with the diagnosis.

[Mistermorgan]

Thanks!!
I did also see something about this, so had the engine idle and tapped on the MAF with the handle of a screwdriver but there was no change in rpm or any stutters. I’m not sure how hard I was supposed to hit but it just looks brittle so didn’t give it much

I also disconnected it and started the car and it runs fine, whilst running I plug it in and it bogs a little bit but then recovers and runs ok again. I’ll get a new Bosch unit and see how I go with it.


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[Mistermorgan]

Have swapped out the MAF with a new Bosch unit and the error has come back again after a drive.

I’m not getting any other codes except the maf signal. Could this potential mean a DME Issue? The intermittent throttle response issue just feels like something could be wrong with the throttle pedal itself but surely they would throw a code?

Anyone have any suggestions?


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[80stech]

Maybe the Foxwell users could chime in. I wouldn't trust it to read all the codes (maybe depends what update you have) and give the proper interpretation. Yes, the throttle pedal has counteracting pots so you would think anything with that would throw a code. You say problem doesn't show up with maf disconnected?

[Mistermorgan]

Actually, that’s a great point. I took it for a drive with MAF disconnected and the same thing which probably does point to something else, just really hoping it’s not a DME replacement given it’s a DME code for signal error.

I’ll have a go at running an inpa scan see if anything else comes up


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[Mistermorgan]

Have scanned with INPA and just have the maf signal error.

Could anyone tell me on live reads why my normal kg/h should be from my MAF?

Is it possible this could be a VANOS issue? Im positive at this stage it’s not the MAF but don’t know where else to look next

Would love some help with this


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[80stech]

What exactly is code description? just "MAF signal error?" You have continuity of the wires so maybe check to see if something is getting grounded, harness rubbed though maybe? That being said, if the problem happens with the MAF unplugged it would suggest that there might be something else going on.

[Bdc101]

Have you ever gotten the "fuel trim exceeded" errors? Or just a MAF signal error? My guess (and it is indeed a complete guess) is that "MAF signal error" means there is something wrong with the signal getting to the DME (since you have replaced the MAF). The typical MAF problems tend to cause fuel trims to be exceeded and not cause the throttle to become unresponsive.



Do the throttle problems associate 1-to-1 with every "MAF Signal Error" code you get? Or do you get that code even when the car is driving fine?



Are you sure the throttle itself is not a problem?



Just brainstorming here - I really have no idea. I agree with 80stech, check continuity of all the wires in the MAF connector back to their source.

[Mistermorgan]

Originally Posted by Bdc101

Have you ever gotten the "fuel trim exceeded" errors? Or just a MAF signal error? My guess (and it is indeed a complete guess) is that "MAF signal error" means there is something wrong with the signal getting to the DME (since you have replaced the MAF). The typical MAF problems tend to cause fuel trims to be exceeded and not cause the throttle to become unresponsive.



Do the throttle problems associate 1-to-1 with every "MAF Signal Error" code you get? Or do you get that code even when the car is driving fine?



Are you sure the throttle itself is not a problem?



Just brainstorming here - I really have no idea. I agree with 80stech, check continuity of all the wires in the MAF connector back to their source.

Sorry - realised I didn’t reply.

The throttle problem does associate 1-1 to the error code being triggered.

Ie - car is driving fine, then the throttle pedal will become unresponsive, like you can push the the floor and it won’t respond. EML light comes on and the code is triggered. Throttle will work ok but sporadically die.


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