Are these symptoms of a faulty MAF? Or something else?

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mikerajjers

Well-Known Member
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1,467
Location
Bedford UK or Trnava SK
I have a 2000 TD5 90 and I cannot get beyond 110-120 kmph. At first I thought this is the standard top speed, but there have been occasions it got to 140kmph with ease and 150kmph going down hill, so there must be a problem somewhere.

It pulls nicely through all gears, steady acceleration up to 110 and then nothing...stays there. I did a few tests connecting and disconnecting the MAF and basically I feel absolutely no difference between having the MAF cables connected or disconnected. I drove for about 60km with the MAF connected, then stopped at a layby, disconnected the MAF sensor and easily got to 140kmph. However, then had to slow down behind a lorry and again car only reached 110kmph after accelerating. I did the same process again 2 times but this time there was no difference, only got to 110kmph

Does the engine go into limp mode or something? Unfortunately I don't have a diagnostic tool.

Also, I recently (on a couple of occasions) felt a judder in power like a woo woo woo (quick and minor losses and gains in power) when rapidly accelerating in 4th and 5th gear. When I eased off the gas and accelerated more gradually the car was fine.

When I bought the car about 3 month ago I took it to a mechanic to check out a small oil leak...when I got home the MAF was disconnected and I don't know if I bought it like this or whether the mechanic unplugged it. I reconnected it and the car seemed to drive better for a brief period.

Am I correct in thinking this is likely to be a faulty MAF sensor or could these symptoms indicate a different issue? I don't think it is the waste gate stuck as I can hear it releasing pressure in lower gears. Could it be the EGR stuck open?

I changed the air filter for a K&N recently, but in hindsight these symptoms existed beforehand.

Any help would be much appreciated.
 
It is widely accepted that if no discernable difference in performance when the MAF is connected or disconnected then the MAF has failed.
When a MAF is giving random information which is outside of normal limits to the ECU the ECU defaults to a pre programed set of data and this data is used on both occasions (faulty MAF and disconnected MAF) and that is why you see no difference in performance.
 
I have taken the car to my mate that looks after it. I've got some new springs and shocks that I want fitting anyway.

He reckons it's either the MAF or the ECU is confused because of the allisport intercooler that he fitted a couple of weeks ago. Anyway, on the drive over car performed beautifully and easily got to 140kmph. I'll keep you posted
 
I have taken the car to my mate that looks after it. I've got some new springs and shocks that I want fitting anyway.

He reckons it's either the MAF or the ECU is confused because of the allisport intercooler that he fitted a couple of weeks ago. Anyway, on the drive over car performed beautifully and easily got to 140kmph. I'll keep you posted

How did you get on did your mate get to the bottom of the problem?
 
I have a 2000 TD5 90 and I cannot get beyond 110-120 kmph. At first I thought this is the standard top speed, but there have been occasions it got to 140kmph with ease and 150kmph going down hill, so there must be a problem somewhere.

It pulls nicely through all gears, steady acceleration up to 110 and then nothing...stays there. I did a few tests connecting and disconnecting the MAF and basically I feel absolutely no difference between having the MAF cables connected or disconnected. I drove for about 60km with the MAF connected, then stopped at a layby, disconnected the MAF sensor and easily got to 140kmph. However, then had to slow down behind a lorry and again car only reached 110kmph after accelerating. I did the same process again 2 times but this time there was no difference, only got to 110kmph

Does the engine go into limp mode or something? Unfortunately I don't have a diagnostic tool.

Also, I recently (on a couple of occasions) felt a judder in power like a woo woo woo (quick and minor losses and gains in power) when rapidly accelerating in 4th and 5th gear. When I eased off the gas and accelerated more gradually the car was fine.

When I bought the car about 3 month ago I took it to a mechanic to check out a small oil leak...when I got home the MAF was disconnected and I don't know if I bought it like this or whether the mechanic unplugged it. I reconnected it and the car seemed to drive better for a brief period.

Am I correct in thinking this is likely to be a faulty MAF sensor or could these symptoms indicate a different issue? I don't think it is the waste gate stuck as I can hear it releasing pressure in lower gears. Could it be the EGR stuck open?

I changed the air filter for a K&N recently, but in hindsight these symptoms existed beforehand.

Any help would be much appreciated.

Did you sort this issue?
 
had maf problems on my 90 and my disco, did not have any of the symptoms what you describe
in fact until i bought the nanocom and plugged it into the 90 i never knew the maf was knackerd
although i suspected there was something up due to clouds of black smoke under heavy load
if your near hemel any time give me a shout and i can stick the nanaocom on it for you
 
Did you sort this issue?
Not yet, he rang me to say it could do with new propshafts and brake caliper pistons so I'll go and collect when it's all done. I bought it earlier this year on a whim with no service history on gut instinct. I don't mind spending money on it as it's a project for me and I want to keep it for a long time
 
had maf problems on my 90 and my disco, did not have any of the symptoms what you describe
in fact until i bought the nanocom and plugged it into the 90 i never knew the maf was knackerd
although i suspected there was something up due to clouds of black smoke under heavy load
if your near hemel any time give me a shout and i can stick the nanaocom on it for you
That is very kind of you but unfortunately the car is in Slovakia
 
Just to give some feedback...it was the MAF sensor and possibly poor quality fuel. Mate changed the MAF and I put in a tank of Shell VPower diesel and its fine. Back on ordinary shell fuelsave and seems ok. I also had the ECU remapped and now have around 160bhp...totally different car.
 
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