Is this a MAF problem?

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giftedboy said:
Hi Mark,
I commented back down the thread I had very similar problem with 300Tdi Auto with what seemed the same the power loss problem.
After leaving it at "alleged 4x4 specialist" who spent 3-4 hours and could not find the fault and told me they needed more time to search for the fault.
I then took it to a 4x4 centre near Banbury who fixed the fault in less than two hours they just repepaired the wiring between the throttle pontimeter and the maf unit.
He said had seen the same problem a number of times on 300tdi's discovery's.
Click to expand...

Thats very interesting as when the MAF is reconnected the problem is unbearable...... hadn't thought about checking the integrity of the wiring. If this potentiometer arrives over the next few days i can reconnect the MAF and see what happens power wise.

You never seem to feel a surge from the turbo kicking in, but i'm fairly sure i can hear it. had a scan through some previous threads and picked up a few things to check/do, hose condition from turbo to intercooler, clean out intercooler and check fuel sedimenter.

..........Mark
 
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Latest update guys, changed the Throttle potentiometer this morning, guess what..... no different. Still got the engine light flashing at me as soon as i let off the pedal slightly. So its not that or the MAF, anyone got any ideas where i might look next???
 
mark george said:
Latest update guys, changed the Throttle potentiometer this morning, guess what..... no different. Still got the engine light flashing at me as soon as i let off the pedal slightly. So its not that or the MAF, anyone got any ideas where i might look next???
Click to expand...

Did you check the wiring??

Is it a second hand potentiometer??
 
Bromsgrove Defender said:
Did you check the wiring??

Is it a second hand potentiometer??
Click to expand...

No, not checked the wiring yet, thought there would be problems all the time if it was wiring, and as the problem only happens when throttle lightly applied might not see a fault when static??

yes a second hand potentiometer..... these things are like gold dust, probably because they are a pig to get off the car, bit cooincidental that this new one demonstrates 'exactly' the same problem to be down to a faulty second hand unit, i'm thinking though??? :confused:
 
giftedboy said:
Hi Mark,
I commented back down the thread I had very similar problem with 300Tdi Auto with what seemed the same the power loss problem.
After leaving it at "alleged 4x4 specialist" who spent 3-4 hours and could not find the fault and told me they needed more time to search for the fault.
I then took it to a 4x4 centre near Banbury who fixed the fault in less than two hours they just repepaired the wiring between the throttle pontimeter and the maf unit.
He said had seen the same problem a number of times on 300tdi's discovery's.
Click to expand...

Just been studying the wiring diagrams following on from Giftedboy's comment earlier, cant see any wiring that links the throttle pot and the MAF, only a black link wire that links up most sensors and terminates at the EDC unit
 
mark george said:
Just been studying the wiring diagrams following on from Giftedboy's comment earlier, cant see any wiring that links the throttle pot and the MAF, only a black link wire that links up most sensors and terminates at the EDC unit
Click to expand...

Dont think they are directly connected but they are through the EDC.
The EDC can only go on the information it gets from the various sensors, so if any of the wiring is duff, you will get a fault code come up in it.

If the second hand Potentiometer is worn, there's a very good chance it will be worn in exactly the same place as your original. i.e. in the place it's held the most, which will be I suspect, somewhere in between the 1000 to 2000 rev position.

If there is no way into it, there surely will be some way of hooking it up to a multimeter and see if there are any clitches in it.

I can pop round with my multimeter and lend you a hand if you like? ;)
 
mark george said:
Just been studying the wiring diagrams following on from Giftedboy's comment earlier, cant see any wiring that links the throttle pot and the MAF, only a black link wire that links up most sensors and terminates at the EDC unit
Click to expand...


What you need to do ideally is to connect it to a Nanocom or Hawkeye device which will show each track of the two or three track throttle pedal potentiometer in live data.

If you don't have access to one, check out the forum in my sig as there is a locator for these devices and you'll probably find someone local to you who has one.
 
I will give the 4x4 specialist in Banbury if you like to find out exactly what wiring they replaced to solve the problem.
There really helpful people I'm sure he wouldn't mind chatting to you either about the fault.
It's EH Douglas in Wardington near Banbury.
 
thebiglad said:
What you need to do ideally is to connect it to a Nanocom or Hawkeye device which will show each track of the two or three track throttle pedal potentiometer in live data.

If you don't have access to one, check out the forum in my sig as there is a locator for these devices and you'll probably find someone local to you who has one.
Click to expand...

Didn't realise Nanocom of Hawkeye were suitable for 300tdi.... but i've noticed a couple of guys in Wolverhampton, not far from work, i'll try to contact them
 
giftedboy said:
I will give the 4x4 specialist in Banbury if you like to find out exactly what wiring they replaced to solve the problem.
There really helpful people I'm sure he wouldn't mind chatting to you either about the fault.
It's EH Douglas in Wardington near Banbury.
Click to expand...

that would be great giftedboy, much appreciated
 
mark george said:
Didn't realise Nanocom of Hawkeye were suitable for 300tdi.... but i've noticed a couple of guys in Wolverhampton, not far from work, i'll try to contact them
Click to expand...



I don't think you'll get anywhere with a Nanocom on a TDi 300, however there are unlock codes for TDi 300 on Hawkeye, so there must be some functionality.
 
Now explain this one!! The wife told me the problem was getting worse to the point it was 'unbearable', so i bit the bullet and booked it in with the local land rover lads for a diagnostic check ASAP (Tuesday this week is the best they could do). It's a bit like waiting for a dentist appointment...... by the time you get one the pain has gone!! This disco has had this problem from the day i got it in January, the day i book it in for diagnostic check the problem vanishes!! No sign of even a blip! took it to work myself today to give it a run down the motorway......perfect!!! Now if i take it in tomorrow i'm gonna look stupid! This has thrown a complete new twist on the saga... does this perhaps point to a fuel problem that has cleared??
 
When Big Red first arrived with me, I had exactly this issue. Drove her home from the seller (about 40 miles), no problem. Couple of days later as I was chugging slowly around a roundabout she almost stalled and the CEL blinked on. For a couple of days this was intermittent and when I took her for a cam belt change and service-to-mileage, they suggested a faulty potentiometer. Quoted about £900 so I politely declined.

Over the next month it happened a couple more times, with no discernible pattern (speed/load/electric demand etc) and I was stumped.

A few weeks later I started my adventure into SVO territory and whilst it may be a coincidence, I've had about 4 months of trouble-free motoring. Maybe the oil cleaned something?

So, the fact that it came and then went doesn't surprise me at all. Be prepared for a re-visit soon. Typical that it stopped as soon as you booked in mind you!

As for the fuel system being blocked, it's as good an answer as any other. It's a common problem and there are more answers than questions.

One thing which does warrant a look though is the question of wiring. It is possible for a wiring fault to present inconsistent behaviour since old wires are highly susceptible to moisture ingress, dust and oxidisation, all of which can cause loss of current.

Good luck.
 
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