Oh no, not another MAF thread!

NikTheGeek · 2nd April 2009, 21:13

Yep, sorry!

Still trying to get to the bottom of my 28mpg (did I mention that?).

I've ran with the MAF disconnected for a week. No difference at all. None. Car revs to 4200 before automatically changing gear, with or without MAF. Car idles fine with or without MAF, car accelerates really well with or without MAF.

Tried a Mafam from Ron, even on its lowest setting it made the car undriveable!

If my MAF was working fine, surely I would notice a degradation in engine performance with it disconnected. Likewise, if it was totally knackered, I'd notice an improvement with it disconnected. What I don't understand is why my car is working and driving perfectly with or without the MAF??? Apart from the poor fuel economy that is.

Is it possible that just part of the MAF is broken? Either the temp sensor or the wire rather than both bits? Is it possible that its disconnected elsewhere in the engine and that when its been plugged in, it actually hasn't? How would I test that? Can I test the maf somehow and get readings from it?

I don't want to spend a small fortune on either a new Bosch MAF or a Pierburg one and a Mafam if the one I have is actually fine and my poor mpg is down to something else (although I've ran out of ideas)...

Anyway, I'm sure someone will be along shortly to come up with some suggestions - no pressure guys!

Nik

M3NDEREZ · 2nd April 2009, 21:19

When my MAF was shot, it drove like a dog under about 2200RPM.. Mind you, different people experience different symptoms aparrently.. Maybe your MPG's at least partly down to the way you dirve? You know, Occam's Razor and all that.. Mine rarely sees anything above 2500RPM..

NikTheGeek · 2nd April 2009, 21:33

Quote:

Originally Posted by M3NDEREZ

Maybe your MPG's at least partly down to the way you dirve? You know, Occam's Razor and all that.. Mine rarely sees anything above 2500RPM..

Hey, what you saying???

Mine rarely sees anything below 4000, but its an auto, it compensates for hard driving. And that sport switch only gets pressed at lights (and any other time I'm stopped) and then switched straight off again once I hit 70(ish)

But seriously, it may be my driving, its still never been on a long run in the 3 months I've had it, I just want to learn/understand why disconnecting ANYTHING on a car can possibly make not a jot of difference! It must do a job, but it doesn't seem to....

mcdonaa · 2nd April 2009, 21:33

Quote:

Originally Posted by NikTheGeek

Yep, sorry!

Tried a Mafam from Ron, even on its lowest setting it made the car undriveable!

I fitted a Synergy 2 to my brother's Freelander TD4 (same engine as 'our' CDTi ones if anyone doesn't know) and turned on the MAF compensator, and it drove really badly! No guts below 2Krpm at all. All I can conclude from that is that since his car has done about 28K miles, his MAF is OK, and the compensation of the Syn2 kinda mucks up the signal!! Its turned off for now!

Sounds similar to your experience, which I lends me to believe that your MAF is OK.

mcdonaa · 2nd April 2009, 21:38

I seem to remember reading someone having a very similar problem, and wasn't due to the engine at all. Have you checked for binding brakes? The chap in question had this problem and caused sub 30mpg from a diesel. Worth a look!

JohnDotCom · 2nd April 2009, 21:39

If a Pierburg MAF the MAF won't work at all without a Mafam or Synergy,
just in case people didn't know and that section must always be turned on.
Seeing no difference is more a sign it doesn't work then does IMHO.
I have lent out a Bosch MAF to a member for testing purposes,
on its return you are welcome to borrow it.
It works but not just at its peak.

M3NDEREZ · 2nd April 2009, 21:39

Quote:

Originally Posted by NikTheGeek

Hey, what you saying???

Mine rarely sees anything below 4000, but its an auto, it compensates for hard driving. And that sport switch only gets pressed at lights (and any other time I'm stopped) and then switched straight off again once I hit 70(ish)

But seriously, it may be my driving, its still never been on a long run in the 3 months I've had it, I just want to learn/understand why disconnecting ANYTHING on a car can possibly make not a jot of difference! It must do a job, but it doesn't seem to....

Honestly, I wasn't being off.. I used to get about 26MPG out of a 1.6 because of the way I drove it! Should have got more like 35MPG, but I just loved the noise at 8250RPM!

Mines an Auto too, though I've driven only Auto's (with a couple of short lived exceptions) for the past 9 years..

As for stuff being taken off, and making not a jot of difference, there's definately precident.. EGR Bypass and Decat are 2 examples - THey actaully make a marked improvement. There's a lot you can strip away that's in no way depremental to the engine, though possibly to the emissions! Not a good idea to run the engine long term with the MAF unplugged though!

M3NDEREZ · 2nd April 2009, 21:40

Quote:

Originally Posted by JohnDotCom

I have lent out a Bosch MAF to a member for testing purposes,
on its return you are welcome to borrow it.
It works but not just at its peak.

Actually, I still have my old shoddy MAF in the box the Pierburg came in.. You're welcome to give it a try and see if there's any difference if you fancy it..?

eddybrown · 2nd April 2009, 21:41

Usually when the maf goes the output signal drops but I've heard Ron say in the past that some Maf sensors can do the opposite and output a signal that is too high. Thus it seams the car is running fine but if you apply a mafam too it the signal will get messed up hence poor performance.

I'm just going off what I've read on here in the past and .org and I might not be right.

JohnDotCom · 2nd April 2009, 21:44

Quote:

Originally Posted by mcdonaa

I seem to remember reading someone having a very similar problem, and wasn't due to the engine at all. Have you checked for binding brakes? The chap in question had this problem and caused sub 30mpg from a diesel. Worth a look!

There is a whole list of possibilities which I believe have been listed in another thread on this.
Includes,

PCV Filter dirty or Blocked.
EGR Blocked
Air Filter Dirty or Blocked Airflow.
Faulty MAF
Fuel Leaks from pipes, Filter or otherwise
Injectors (can't remember why but someone gave a reason)
Brakes Binding
Tyre Pressures Incorrect (to low)
Handbrake not correctly releasing.
Even faulty ECU.

The List goes on.

Also have you checked for codes on a T4 not a Code reader?

2nd April 2009, 21:13	#1
NikTheGeek Gets stuck in 2002 Range Rover P38 Join Date: Dec 2008 Location: Wigan Posts: 593 Thanks: 0 Thanked 0 Times in 0 Posts	Oh no, not another MAF thread! Yep, sorry! Still trying to get to the bottom of my 28mpg (did I mention that?). I've ran with the MAF disconnected for a week. No difference at all. None. Car revs to 4200 before automatically changing gear, with or without MAF. Car idles fine with or without MAF, car accelerates really well with or without MAF. Tried a Mafam from Ron, even on its lowest setting it made the car undriveable! If my MAF was working fine, surely I would notice a degradation in engine performance with it disconnected. Likewise, if it was totally knackered, I'd notice an improvement with it disconnected. What I don't understand is why my car is working and driving perfectly with or without the MAF??? Apart from the poor fuel economy that is. Is it possible that just part of the MAF is broken? Either the temp sensor or the wire rather than both bits? Is it possible that its disconnected elsewhere in the engine and that when its been plugged in, it actually hasn't? How would I test that? Can I test the maf somehow and get readings from it? I don't want to spend a small fortune on either a new Bosch MAF or a Pierburg one and a Mafam if the one I have is actually fine and my poor mpg is down to something else (although I've ran out of ideas)... Anyway, I'm sure someone will be along shortly to come up with some suggestions - no pressure guys! Nik

2nd April 2009, 21:19	#2
M3NDEREZ Posted a thing or two R75 DUB Saloon Connoisseur CDT + Synergy2 Join Date: Dec 2008 Location: Earlswood, Surrey Posts: 1,344 Thanks: 0 Thanked 0 Times in 0 Posts	When my MAF was shot, it drove like a dog under about 2200RPM.. Mind you, different people experience different symptoms aparrently.. Maybe your MPG's at least partly down to the way you dirve? You know, Occam's Razor and all that.. Mine rarely sees anything above 2500RPM.. __________________ [SIGPIC][/SIGPIC] STILL WANTED: Black Leather & Chrome Auto Gearknob, Diesel Cruise ECU, EGR Bypass.

2nd April 2009, 21:38	#5
mcdonaa Avid contributor 2002 ZT-T 190 Join Date: Mar 2009 Location: St.Leonards-On-Sea Posts: 137 Thanks: 10 Thanked 0 Times in 0 Posts	I seem to remember reading someone having a very similar problem, and wasn't due to the engine at all. Have you checked for binding brakes? The chap in question had this problem and caused sub 30mpg from a diesel. Worth a look! __________________ 2002 Le Mans Green ZT-T+ 190 [SIGPIC][/SIGPIC]

2nd April 2009, 21:41	#9
eddybrown Gets stuck in Rover 75 Club CDT & 73' MG Midget Join Date: Dec 2007 Location: Peterborough Posts: 543 Thanks: 0 Thanked 1 Time in 1 Post	Usually when the maf goes the output signal drops but I've heard Ron say in the past that some Maf sensors can do the opposite and output a signal that is too high. Thus it seams the car is running fine but if you apply a mafam too it the signal will get messed up hence poor performance. I'm just going off what I've read on here in the past and .org and I might not be right. __________________ http://www.eddybrown.co.uk/images/userbar_ed.png http://www.eddybrown.co.uk/images/userbar_mg.png

2nd April 2009, 21:39	#6
JohnDotCom * Rover 75 FaceLift Tourer CDTi 170BHP Auto ConnSE 2005 Model Starlight Silver Join Date: Nov 2006 Location: Abergele Posts: 28,735 Thanks: 0 Thanked 6 Times in 5 Posts	If a Pierburg MAF the MAF won't work at all without a Mafam or Synergy, just in case people didn't know and that section must always be turned on. Seeing no difference is more a sign it doesn't work then does IMHO. I have lent out a Bosch MAF to a member for testing purposes, on its return you are welcome to borrow it. It works but not just at its peak.