P38A To MAF or not to MAF, that is the question.....

....Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take Arms against a Sea of troubles,
By replacing the MAF that may be at odds,
To the smooth running of my V8.

.......Right, OK.....

MAF Plugged in she runs and idles a bit poo, will rev freely all the way up and down, may stutter at the end but picks up again. When driven, doesn't like being under load, then will surge and off she goes, then tries to di and struggles - into Neutral rev her up and she's fine, back into Drive and she'll not want to accelerate again.

MAF gets unplugged while running, engine will die

MAF unplugged before start, engine will start and idle *reasonably* well....and when driven, minor hesitation and the odd pop and fart, but runs under load albeit with *reservation* but still accelerates as long as you don't push it......

So to [replace the] MAF, or not to [replace the] MAF, that is the question......

I don't know if its the same as a diesel one, but I have a new one in my shed still in the wrapper if you need one

Saint....

was it ok before you had head off?

myfirstl322 said:

Saint....

was it ok before you had head off?

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Nope - the heads off was to see what was tapping - the powerloss was still there previously.

Sounds like a maf issue to me. The ecu has a strategy to run without the maf using other sensors for the base load. This is gems isn't it?
If it is and you've got nanocom I'll dig out the test voltages.

I can't find the rpm v voltage readings. There from a jaguar x300/aj16 repair manual. I used to have copies but can't find them anymore. They both use the Lucas sagem 20AM maf. The bodies are slightly different though. But at a push they will work vice versa. It's probably easier just to substitute to be honest. Mine was a 1/4v down across the range and it caused lean misfires all the time and eventually conking.

Theres one on eBay but 4 x300 mafs.

It is a GEMS - and I don't have a Nanocom unfortunatley.

I am really leaning toward MAF issues from my research.....

@Dopey - Many thanks, but the Diesel and the Petrol MAFs are different !

Saint.V8 said:

It is a GEMS - and I don't have a Nanocom unfortunatley.

I am really leaning toward MAF issues from my research.....

@Dopey - Many thanks, but the Diesel and the Petrol MAFs are different !

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My Nanocom does GEMS. Will it go as far as Bucks?

Does the GEMS engine handle ODB2?

Grrrrrr said:

My Nanocom does GEMS. Will it go as far as Bucks?

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I have no idea if it will make it out of the secure site at work - not only because it is 'limping' at times, but also because it is not taxed, MOT'd or insured!

Grrrrrr said:

Does the GEMS engine handle ODB2?

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It does have basic OBD2 data available.... gonna plug it in tomorrow to my ELM327 interface and see if that shows anything.

Saint.V8 said:

I have no idea if it will make it out of the secure site at work - not only because it is 'limping' at times, but also because it is not taxed, MOT'd or insured!


It does have basic OBD2 data available.... gonna plug it in tomorrow to my ELM327 interface and see if that shows anything.

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Ah. And this secure compound requires passes, presumably. How far from Aylesbury?

Grrrrrr said:

Ah. And this secure compound requires passes, presumably. How far from Aylesbury?

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Farnborough, so a bit of a trek.....Secure as in passes and Security clearances etc....but able to drive it out into the visitors car park!

Will see if I can get something from the OBD2 interface tomorrow - if I can remember where my ELM327 is - and report back.

Saint.V8 said:

Farnborough, so a bit of a trek.....Secure as in passes and Security clearances etc....but able to drive it out into the visitors car park!

Will see if I can get something from the OBD2 interface tomorrow - if I can remember where my ELM327 is - and report back.

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OK. Will wait and see. If I jump in the Jag it won't take long, just hope to dodge the camaras.

Saint.V8 said:

if I can remember where my ELM327 is - and report back.

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got mine sitting my 'electronics bag' i'll grab it in the morning.. i'm only the on the other side of side Farnborough airport. text me if you need it i'll make sure i stick in the car just in case

Thats a bit strange, my dealings with maf on petrol engines its always been a case of get it started with maf plugged in, pick revs up to fast idle then un plug maf if car then runs and performs as it you would expect its strong possibility its maf, normally find petrol dont like to restart with maf unplugged, would have thought something like easyobd with elm 327 would give you some sort of reading. I have Torque lite app on my phone and bluetooth dongle I carry in the car for when I get "While you`re here can you plug my car in please the engine lights on" for what it cost it seems quite effective.

Usually with a petrol engine that will not start but does when the MAF is unplugged a new MAF is needed. However in this case maybe the MAF is not totally duff and is at times sending implausible info to the ECU.

Many thanks to @Grrrrrr and @ukadamwest for their offers to plug in if I get stuck....

Found my ELM327 OBD2 interface this morning - happened to be in the other Range Rover that is also off the road at the moment!

I think this is fairly definitive (MAF connected during this diagnostic session):



Cleared them down and haven't returned but the running with MAF connected is hit and miss, whereas with it disconnected it runs *OK* with the odd stumble, but is more consistantly *OK* then with the MAF plugged in!!

Google say's
P1178 is o2 sensor.
P1176 is post cat correction

Maf would do that, I think.

Maf eezy

Saint.V8 said:

... - happened to be in the other Range Rover that is also off the road at the moment!

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2 Rangie's in need of repair? What were the chances of that happening?!

Looks like you have a way forward. Glad to hear that as I'm helping a mate with a chainlink fence tomorrow and was wondering how to fit you in!