Air Flow Sensor, 2L petrol.

[GreenBongo]

If the ECU is flagging a MAF error then it will revert to a failsafe mode based on Throttle Position and RPM, its a very crude alrorithm and performance and MPG will be reduced. You have to clear the MAF error to get it to run correctly.

helen's answer may be some help to the person that was looking to force the ECU into limp mode.

[dunslair]

Thanks for the replies.

We are getting to the stage that any ideas are worth considering, even if they appear unrelated. The van has just been all the way to France and back (having thought the MAF sensor problem was fixed) but with hindsight the van was not running as well as we could normally expect. i put the loss of power, which was not noticeable on flat motorways, down to us being heavily loaded.

We have a really good mechanic, who is an auto electrician, so I have a lot of faith that he will get to the bottom of the problem. I think he is just looking for some help in thinking outside / around the box.

Thanks again for your help.

Cheers

David.

[GreenBongo]

If you can't find an issue with the MAF then check the TPS setting I would think that the airflow is tested against a value calculated from TPSvRPM.

[dunslair]

Thanks.

I will suggest checking TPS setting. The rpm is very slow to lift, and I think the idle speed is less than it was (but not enough to cut out). The revs take a long time to build up when in drive, but they still appear to pick up OK when in neutral.

Cheers

David.

[dunslair]

Looking in the service manual code 0120 is for throtle sensor signal system. Code 0100 is the airflow signal system and code 0110 is the air intake sensor signal system. I'm confused!! I wonder if it is the throtle sensor we should be looking at?

Any thoughts appreciated.

Cheers

David.

[GreenBongo]

I don't know how the MAF is wired on these but from those three codes I would think that somewhere you're missing the 5V sensor supply, probably a bad connection but could be a short in the loom.

[dunslair]

I have also noticed of late that I don't get that 'woosh' when I unscrew the filler cap. I have checked the gauze filter on the cap and all appears fine. With the value of hindsight I think the problem may have shown itself since the last service in June, and steadily got worse. I wonder if it could be a problem with the fuel filter as well? Wonder if it would be worth getting the garage to change fuel and air filters as well as spark plugs? It may not be related, but at the moment I am wracking my brains to work out when this problem began to show itself.

Any thoughts would be gratefully appreciated.

Regards

David.

[GreenBongo]

You won't always get that woosh, it depends on how long its been driven since the tank pressure was purged. If you don't know when the filters were changed then I would do those anyway, I would also check that the spark plugs were properly gapped.
It won't run right while you have those codes because the ECU will be running in a failsafe mode.

[dunslair]

You won't always get that woosh, it depends on how long its been driven since the tank pressure was purged. If you don't know when the filters were changed then I would do those anyway, I would also check that the spark plugs were properly gapped.
It won't run right while you have those codes because the ECU will be running in a failsafe mode.

Apparently it automatically cleared the error code when we fitted the genuine Mazda MAF sensor. But this looks like it may have been wishful thinking on the part of the lad who fitted them. All filters were replaced in June when the van was serviced about 4K miles ago.

[GreenBongo]

Yes once the fault is gone the code will clear. The codes that you quoted a couple of posts above - are they still showing or have all codes gone now?

[Simon Jones]

I changed the fuel filter on my V6 a while back & was amazed at the amount of crud that came out of it. It's a very easy to overlook changing it due to its inaccessibility.

http://www.igmaynard.co.uk/bongo/forum/ ... uel+filter

[dunslair]

Yes once the fault is gone the code will clear. The codes that you quoted a couple of posts above - are they still showing or have all codes gone now?

I don't think all of the codes above were showing (I just flagged them on here because they were all similar). The one the mechanic quoted to me appeared from my check in the manual was the throttle position sensor and not the MAF sensor. (but in fairness he was working with his own manual for fault diagnosis and not the Service manual.)

We will get to the bottom of this! Its booked back in on Tuesday.

[dunslair]

I changed the fuel filter on my V6 a while back & was amazed at the amount of crud that came out of it. It's a very easy to overlook changing it due to its inaccessibility.

http://www.igmaynard.co.uk/bongo/forum/ ... uel+filter

Yep. I think it is a little bit easier to get at on the 2L. I assume they changed it, I gave them a replacement one to fit in June. Will get them to check anyway.

Cheers

David.

[dunslair]

Well D Day today, van booked into the garage for a thorough investigation.... wish us luck. picking up on JohnL's thread I will get them to check the O2 sensor as well as all the others (TPS, Air flow, plugs, cam position sensor, fuel and air filters, fuel pump etc)

Managed to flood it yesterday on a small incline pulling away from a busy junction. Not fun trying to roll back out of the way with only hand brake and no power steering, but let it sit for a few minutes before I got it going again. I really wish the van was a manual not auto.

[dunslair]

It looks as if the problem is with the ECU, so in the words of the mechanic, he is going to ' build it back up, run a couple of other tests and then send the ECU off to a company he uses for testing and fixing if required'. Has anybody else had to go down this route?

Cheers

David.