P38A MAF woes

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cornishboater

cornishboater

Well-Known Member
Posts
710
Location
Poole, Dorset
Right, I have checked the old MAF with the Nanocom and it came up with fault 102 circuit low input. I cleared it and restarted but the fault returned. I have 2 brand new MAFs so I installed the first and tried starting, the thing just threw out black smoke and wouldn't rev above 200RPM and sounded as if it had choke full on, I got it to idle at about 50 RPM and pulled the plug out, it immediately went to 600 RPM and cleared itself. Plugged it back in and restarted the car and the same thing happened. So I tried MAF number 2 and exactly the same thing happened. Then I plugged the old one back in and it ran ok but still had the hesitation when trying to rev. I plugged the Nano in again and the same fault appeared, cleared it, switched off and restarted and tested again, same fault. Just to be sure I did it a 3rd time, this time the fault cleared and the hesitation disappeared. Obviously there is an issue with the old MAF (I did clean it with MAF cleaner prior to this) I reset adaptive settings but nothing changed with the new MAFs I had looked on the tinternet and there was a bit that said you could reset the MAF on its own, I could only find the one page where it just said reset adaptive settings which I assume is all of em. I obviously cannot drive the thing with the new MAF to allow it to adapt to the new unit/s any suggestions. Right royal pain this is, I have a feeling the issue I have had is that the old MAF threw a wobbly a while ago as there was no perceivable difference with it unplugged. Cheers
 
cornishboater said:
Right, I have checked the old MAF with the Nanocom and it came up with fault 102 circuit low input. I cleared it and restarted but the fault returned. I have 2 brand new MAFs so I installed the first and tried starting, the thing just threw out black smoke and wouldn't rev above 200RPM and sounded as if it had choke full on, I got it to idle at about 50 RPM and pulled the plug out, it immediately went to 600 RPM and cleared itself. Plugged it back in and restarted the car and the same thing happened. So I tried MAF number 2 and exactly the same thing happened. Then I plugged the old one back in and it ran ok but still had the hesitation when trying to rev. I plugged the Nano in again and the same fault appeared, cleared it, switched off and restarted and tested again, same fault. Just to be sure I did it a 3rd time, this time the fault cleared and the hesitation disappeared. Obviously there is an issue with the old MAF (I did clean it with MAF cleaner prior to this) I reset adaptive settings but nothing changed with the new MAFs I had looked on the tinternet and there was a bit that said you could reset the MAF on its own, I could only find the one page where it just said reset adaptive settings which I assume is all of em. I obviously cannot drive the thing with the new MAF to allow it to adapt to the new unit/s any suggestions. Right royal pain this is, I have a feeling the issue I have had is that the old MAF threw a wobbly a while ago as there was no perceivable difference with it unplugged. Cheers
Click to expand...
That's a new one on me, not heard of adaptive settings on these vintage MAF's, I thought they were plug n play.
 
Yes the Maf is plugnplay but the ECM had learnt the behaviour/ cleanliness of the MAF, and if you gave it a thorough clean you wd indeed need to reset the adaptive values. When I cleaned mine and refitted without resetting it immediately idled to 1000rpm, but a reset solved that straight away.
Like earlier suggestion ...maybe give the connector a good clean if you already cleaned the maf
 
romanrob said:
Yes the Maf is plugnplay but the ECM had learnt the behaviour/ cleanliness of the MAF, and if you gave it a thorough clean you wd indeed need to reset the adaptive values. When I cleaned mine and refitted without resetting it immediately idled to 1000rpm, but a reset solved that straight away.
Like earlier suggestion ...maybe give the connector a good clean if you already cleaned the maf
Click to expand...
Diesel or petrol? If diesel, I'm missing something, I have never seen anything about resetting MAF adaptive values in Faultmate.
 
Since I put the original MAF in the engine is doing what it is supposed to so I am assuming the other bits are doing what they should, I will run a check though. I would like to put one of the new ones on though because I don't trust the old one seeing as it threw a fault previously. I just cannot see on the Nano where to reset the MAFs values as I assume this is why it is seriously over fuelling when installing either of the 2 new MAFs. If it had been one of them I would have thought that it might be duff but because both do the same thing it has to be the adapted values. The MAFs are from different suppliers and are different makes so hopefully that rules out the pair being no good. I shall have to search through the Nano to see if I am missing something!
 
cornishboater said:
Since I put the original MAF in the engine is doing what it is supposed to so I am assuming the other bits are doing what they should, I will run a check though. I would like to put one of the new ones on though because I don't trust the old one seeing as it threw a fault previously. I just cannot see on the Nano where to reset the MAFs values as I assume this is why it is seriously over fuelling when installing either of the 2 new MAFs. If it had been one of them I would have thought that it might be duff but because both do the same thing it has to be the adapted values. The MAFs are from different suppliers and are different makes so hopefully that rules out the pair being no good. I shall have to search through the Nano to see if I am missing something!
Click to expand...
There are no adaptive values to reset on the diesel, the MAF is plug n play.
It does sound as if you may have a connector problem
 
Last edited:
Datatek said:
There are no adaptive values to reset on the diesel, the MAF is plug n play.
It does sound as if you may have a connector problem
Click to expand...
Hi Keith, I would have thought that if it was the connector or connections that it would make no difference with it plugged or unplugged. If I start the car with either of the new MAFs the thing overfuels and I cannot get it to rev, if I pull the plug it then runs and if I plug the thing back in it doesn't change until I restart and then it does the overfuel again. The old MAF seems to be working ok now but has thrown a 103 when I started this morning, once I clear the fault it doesn't come back (yet). I tried again this AM just in case but no difference, just overfuels and chugs black smoke. Sounds like the caterpillar diesels in the boat I once had when starting with no pre heat :)

I haven’t tried this yet but I have found another comment on the Aussie site that says if you disconnect the earth on the battery for 30 mins the adaptive settings on the MAF resets to factory. Anyone know if this is true?
 
cornishboater said:
Hi Keith, I would have thought that if it was the connector or connections that it would make no difference with it plugged or unplugged. If I start the car with either of the new MAFs the thing overfuels and I cannot get it to rev, if I pull the plug it then runs and if I plug the thing back in it doesn't change until I restart and then it does the overfuel again. The old MAF seems to be working ok now but has thrown a 103 when I started this morning, once I clear the fault it doesn't come back (yet). I tried again this AM just in case but no difference, just overfuels and chugs black smoke. Sounds like the caterpillar diesels in the boat I once had when starting with no pre heat :)

I haven’t tried this yet but I have found another comment on the Aussie site that says if you disconnect the earth on the battery for 30 mins the adaptive settings on the MAF resets to factory. Anyone know if this is true?
Click to expand...
There are no adaptive setting for the MAF on the diesel. all of the above could still be a dodgy connection. Worth checking that the MAP sensor is working.
 
Datatek said:
There are no adaptive setting for the MAF on the diesel. all of the above could still be a dodgy connection. Worth checking that the MAP sensor is working.
Click to expand...
Mines a 4.6 HSE Petrol, where do I check the MAP? When I replaced the MAF 11 years or so ago I just fitted it, plugged it in and all was ok, this time not so. The MAF shows up when doing the fault check so I would assume again that the thing is connected because I can clear the fault and when re-starting the fault is cleared
 
cornishboater said:
Mines a 4.6 HSE Petrol, where do I check the MAP? When I replaced the MAF 11 years or so ago I just fitted it, plugged it in and all was ok, this time not so. The MAF shows up when doing the fault check so I would assume again that the thing is connected because I can clear the fault and when re-starting the fault is cleared
Click to expand...
Arrgh I thought it was a diesel. Ignore everything that I have said it's an old age thing!!. I know nothing about the petrol I'm pleased to say.
 
There's only one Adaptive Values Reset in Nanocom for either GEMS or Thor. (Can't remember which you have) No option to reset MAF, O2, etc separately because the ECU learns using all of the sensors together.

Have you also checked the O2 sensors are switching properly ? Also check for air leaks after the MAF - ideally smoke test.

1754766135442.png


GEMS

1754766313396.png
 
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