MAF Fault that isn't the MAF....

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Henry_b said:
No no
The electrical manual is a MOFO!

Taking me ages to leaf through it!!

Hang on..
Click to expand...

You can take your time, next few days is fine. I would like the car running nice though and if it turned out to be a bad wire I would be over the moon because I can fix that :cool:
 
Henry_b said:
Ahh good point..

Forgot about them ;)
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Indy said the cats & O2's are working beautifully. The O2's were replaced 18k miles ago with Bosch ones. No expense spared, but the compute stated diagnostic check complete, MAF fault found. He didn't specify any range, only that he was convinced it's a wiring fault to the MAF.
 
Doo said:
Not sure where to go with this... I've got a problem that's been present for such a long time.

I had the local indie plug in his (exceptional) code reader ages ago and it came up with a MAF fault, so I bought a Bosch replacement and nothing changed.

I figured I'd wasted money and swapped back as the issue was still there, like a misfire.

I replaced plugs, leads and all sorts, but STILL this bastard misfire just on throttle. Clears upon hard throttle.

Got it code read again and it showed the MAF is at fault o_O

He thinks I have a wiring fault & he thinks it's the LPG wiring. However, the car runs the same on LPG and petrol, but the misfire is a tiny bit more pronounced on LPG (I would imagine because it's slightly less powerful).

I'm not convinced it's the LPG wiring, but the MAF plug checks out.

So has anyone discovered an issue with a MAF that turned out to be related (ECU, wiring somewhere in the loom, etc).

But if it was connected to the LPG wiring, where should I start because as I said, I'm not convinced it's been wrongly done, although I stand to be corrected. So where should I start with that aspect?

It's so bloody annoying :mad:
Click to expand...
That's why the diesel is better:p:D
 
Doo said:
Indy said the cats & O2's are working beautifully. The O2's were replaced 18k miles ago with Bosch ones. No expense spared, but the compute stated diagnostic check complete, MAF fault found. He didn't specify any range, only that he was convinced it's a wiring fault to the MAF.
Click to expand...

Have you tried running with MAF disconnected?
 
Grrrrrr said:
Have you tried running with MAF disconnected?
Click to expand...

Not yet, but I did think about it. However, 3 MAF's can't all be wrong surely? The original and two (new) Bosch ones o_O from same indy dealer...

It has been suggested I have a leak, which I did have, but I found it and fixed it (I even reported it on here if I recall correctly) That was the stupid connection from/to the Idle Control Valve because some clown at LR thought a wrist watch shaped clip and a circle of rubber was a great idea. But it wasn't, it was a shite idea because it came loose and the rubber ring piece wore away. My fix was to drill the hole bigger, insert the pipe from the inside and glued the lip with Tiger Seal. I "KNOW" it hasn't leaked since, mainly because it's super tight and besides, it's scared to leak again :p

I am not convinced I have another leak, although I won't rule it out.

It has also been suggested the PCV is choked, which is also a possibility because the rockers do weep, even though I replaced the left one. But I am at a loss as to how would a PCV block on an engine that has covered only 19k miles. That's right, nineteen thousand miles is nothing! :eek: The only thing I can think is a slight possibility is that it may have got blocked by sitting for 5yrs, but then it had barely covered 2000 miles at the time it was parked (I have every service schedule and invoice as well as word direct from the man who installed the engine under warranty) and the 1st thing I did upon buying the car was a huge service inc oil & filters. You all know I have treated this car like a princess & the oil gets changed around every 6000 miles so it's had 3 changes and is due another.

I am liking the PCV idea, but not convinced. The other suggestion was a (slightly) blocked cat, but again I'm not convinced because this car just doesn't run rich in general, especially with the LPG system doing 80% of the fueling :rolleyes: The cat "issue" is an easy fix by removing and putting straight through pipes in. But while the torque (and noise) will increase, who's to say it would cure the hesitation?

Then there is the TPS, but again, the code reader (which is a proper job worth thousands of pounds and the local dealership comes to him for code reading, not to mention he knows exactly how to use this device, it's his bread & butter) said only MAF problem.

So how do I go about convincing him to do a live data while driving around and wouldn't this device flag up the TPS as faulty? It found the O2 sensors are great, no plug, lead or coils issues flagged up (except when I pulled a plug lead off)????

If I knew what to expect on which wire at the MAF plug then I could use my digital meter to read any signal along those wires.

Apart from this, the engine can sit for weeks at a time and fire up first turn of the key. It idles beautifully and at full chat the car flies. I can go up Drumossie at 90mph (ahem, should I wish to :p) so power is there.

To me, it feels like if it had a distributor, that it was worn, so the spark timing wobbled upon throttle demand! If on hard acceleration, it does what you ask. On gentle first push on the pedal, I get this hesitation....
 
Doo said:
Not yet, but I did think about it. However, 3 MAF's can't all be wrong surely? The original and two (new) Bosch ones o_O from same indy dealer...

It has been suggested I have a leak, which I did have, but I found it and fixed it (I even reported it on here if I recall correctly) That was the stupid connection from/to the Idle Control Valve because some clown at LR thought a wrist watch shaped clip and a circle of rubber was a great idea. But it wasn't, it was a shite idea because it came loose and the rubber ring piece wore away. My fix was to drill the hole bigger, insert the pipe from the inside and glued the lip with Tiger Seal. I "KNOW" it hasn't leaked since, mainly because it's super tight and besides, it's scared to leak again :p

I am not convinced I have another leak, although I won't rule it out.

It has also been suggested the PCV is choked, which is also a possibility because the rockers do weep, even though I replaced the left one. But I am at a loss as to how would a PCV block on an engine that has covered only 19k miles. That's right, nineteen thousand miles is nothing! :eek: The only thing I can think is a slight possibility is that it may have got blocked by sitting for 5yrs, but then it had barely covered 2000 miles at the time it was parked (I have every service schedule and invoice as well as word direct from the man who installed the engine under warranty) and the 1st thing I did upon buying the car was a huge service inc oil & filters. You all know I have treated this car like a princess & the oil gets changed around every 6000 miles so it's had 3 changes and is due another.

I am liking the PCV idea, but not convinced. The other suggestion was a (slightly) blocked cat, but again I'm not convinced because this car just doesn't run rich in general, especially with the LPG system doing 80% of the fueling :rolleyes: The cat "issue" is an easy fix by removing and putting straight through pipes in. But while the torque (and noise) will increase, who's to say it would cure the hesitation?

Then there is the TPS, but again, the code reader (which is a proper job worth thousands of pounds and the local dealership comes to him for code reading, not to mention he knows exactly how to use this device, it's his bread & butter) said only MAF problem.

So how do I go about convincing him to do a live data while driving around and wouldn't this device flag up the TPS as faulty? It found the O2 sensors are great, no plug, lead or coils issues flagged up (except when I pulled a plug lead off)????

If I knew what to expect on which wire at the MAF plug then I could use my digital meter to read any signal along those wires.

Apart from this, the engine can sit for weeks at a time and fire up first turn of the key. It idles beautifully and at full chat the car flies. I can go up Drumossie at 90mph (ahem, should I wish to :p) so power is there.

To me, it feels like if it had a distributor, that it was worn, so the spark timing wobbled upon throttle demand! If on hard acceleration, it does what you ask. On gentle first push on the pedal, I get this hesitation....
Click to expand...

If you unplug it then I assume it will run on default values. If runs OK then guess it must be the problem. I think you are right in that 3 sensors cannot all be wrong so that then points at an internal break in a wire (pinched anywhere?) or a connector is corroded.
 
Ruled out the air intake system.

Never really thought it was that anyway, but... I bought carb/brake cleaner and sprayed it all over each inlet pipe, duct and connection and there was no increase or decrease in RPM.

So, going by the indication that the MAF is faulty, it is entirely possible that a wire may be responsible (the MAF fault was deleted, then it returned immediately) so since there appears to be no leak suggesting a weak mix, requiring fuel enrichment, I think I can rule out the O2 sensors and such.

The indy is convinced it was a wiring issue and I am inclined to start looking there.

I plan to look at the loom from the MAF back.

If anyone has any suggestions as to where the loom "may" be damaged which would point to a MAF issue being logged, I will be delighted to investigate.
 
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