1.4 TDI - Loss of Power

mjs4x4

A2OC Donor
Anybody had this one in a 1.4 TDI before?

About a week ago, accelerating up a hill the car suffered a loss of power (one minute it was pulling hard - next it was struggling up the hill). Car was like this for the whole journey to work - no power on wide throttle openings but ok on a gentle throttle. By the time I got to work I had convinced myself the mass airflow sensor had failed.

Lunchtime I start it up and it's back to normal (and continues to run normally for over a week and 500+ miles)!!

This morning the same thing happens - dramatic drop off in power going up a hill with a reasonably wide throttle opening. This time I stop, turn off the engine and restart - and it's back to normal immediately (and has been for the rest of the day).

No warning lights are lit. Mechanic was inclined to same view as me - MAF sensor - but he reckons these either work or they don't - not likely to fail intermittently.

Ideas appreciated??



Mike
 
Sounds to me like a MAF sensor

I had to replace one on my old Bora TDI but replaced it with a mercedes cdi one instead as it was £100 cheaper than the VAG one and it improved the performance as it reved more freely.

Dont know if they would work on the lil A2's though.
 
When MAFs are on their way out, they can be intermittant for a while.

If you unplug the MAF and run the car for a week or so, you can see if the problem recurs - if not, then you have your culprit, if it does come back, then time to look elsewhere.

Running the engine with the MAF disconnected will make the engine revert to basic settings and will not harm the engine.

Cheers,

Mike
 
Hi Mike
You could try cleaning the MAF sensor just to ensure there is no debris in there which gets sucked onto the sensor under full load. The unit is fairly easy to remove - but you do need a torx security bit to unscrew the two fixing screws
http://www.a2oc.net/forum/showthread.php?t=4961&highlight=airflow

Another possibility is that one of the small hoses which go to the turbo boost capsule could be affected by the engine moving under load. - Its a long shot but it could be pinched or cracked for example. If it was this, the lack of turbo boost would show up on a diagnostic scan

Cheers Spike
 
I experienced this exact same fault 2 months ago. I cleaned the MAF using just an air duster (!) and since then the problem has not re-occurred :D

Ian
 
spike said:
Another possibility is that one of the small hoses which go to the turbo boost capsule could be affected by the engine moving under load. - Its a long shot but it could be pinched or cracked for example. If it was this, the lack of turbo boost would show up on a diagnostic scan

I don't suffer the exact same symptom, but under heavier loading the power delivery on my TDI is what could be described as 'hesitant' under full throttle. Full accelerator application in second and third is okay, move up to forth and fifth and it is a different story. Mike, (Skipton01), suggested that I try disconnecting the MAF, but for me this made no difference. Having had a remap, the fault is much more noticeable and I am having a full rolling road test conducted at Stealth in an attempt to finally bottom this out.

Interesting theory though Spike, I truly hope that a cracked or pinched pipe will be the cause of my dilemma and possibly the answer to Mike's fault too and not a more expensive or problematic fix.

Cheers,

Darren
 
Having watched Tank on the Stealth rolling road last Saturday, you'll be amazed at the amount of movement the engine makes when accelerating - about 4 inches or so towards the back of the engine bay.

Cheers and fingers crossed,

Mike
 
Skipton01 said:
Having watched Tank on the Stealth rolling road last Saturday, you'll be amazed at the amount of movement the engine makes when accelerating - about 4 inches or so towards the back of the engine bay.

Cheers and fingers crossed,

Mike

4 inches in certain contexts may not seem like much, :)D), but in terms of engine movement that does seem considerable.

With not much room to manoeuvre around the engine bay, I guess it isn't beyond all possibility that a slight crack or pinch may be present, (which has been missed by myself and the Audi Technician), and under heavier loading with maximum engine movement, this then becomes more problematic to the fuel/air mix/turbo?! :confused:

As you say Mike... fingers crossed!!

Cheers,

Darren
 
Thanks for the input everybody.

Will get the sensor out and give it a clean to start with.

I have settled into a routine with it now. It fails about a mile from home after a cold start. I pull into a layby, switch off the engine, restart it, and all is well.

The joys of modern engine electronics!


Mike
 
mjs4x4 said:
Thanks for the input everybody.

Will get the sensor out and give it a clean to start with.

I have settled into a routine with it now. It fails about a mile from home after a cold start. I pull into a layby, switch off the engine, restart it, and all is well.

The joys of modern engine electronics!


Mike

That is exactly my prob - is your one chipped/remaped? and how many miles does your one have on the clock
 
No - it's not chipped - 62,000 miles.

The curious thing is that the loss of power only happens once (as I said - about a mile from home, going up a hill with a wide throttle opening). Once I have stopped and re-started I know it will be ok!!!


Mike
 
Like I said, mine behaved exactly the same.. never on the way to work but always within the first mile after leaving! I didn't pull over though, a rolling restart did the job (including the key removal!) - just keep the clutch out!

Ian
 
driveforward said:
Like I said, mine behaved exactly the same.. never on the way to work but always within the first mile after leaving! I didn't pull over though, a rolling restart did the job (including the key removal!) - just keep the clutch out!

Ian


I know there could be other reasons, but will try this one first
 
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