D5254T (to 2002, Audi) - Flat Spot?

Ian HT · Jan 7th, 2012, 11:10

Hi All,
My V70 TDI 1999 (manual, 167,000 miles) has developed a quirk...It is not a problem yet as it drives corectly 99.9% of the time.
However, if I accelerate hard - say, speeding up on a slip road onto the bypass - when in 3rd and 4th I notice that the hard acceleration drops off just a fraction for a second then goes back to normal. It is a very faint effect so that a passenger probably wouldn't notice, but it is there: repeatable if I slow a bit and put my foot down again.
No funny noised noticed (except sometimes a slight short growl when lifting off to change gear 1st to 2nd and 2nd to 3rd, which I thought was the metal strip on the back of the engine top cover vibrating).
Has anyone had this and diagnosed it? I would be very grateful for ideas as a starting point...
Happy New Year to all, by the way!
Ian

artiedtke · Jan 7th, 2012, 13:32

At around what rpm's ???

Mine is quite gutless until 2000rpm then it flies....

Ian HT · Jan 7th, 2012, 14:53

Hi -mine is nothing special until around 1900 rpm then flies. That's normal - it has always ben that way!
I went out this morning and tried again - when pulling well in say 3rd gear, around 3000 rpm there is a slight lull before it regains full strength. It then seemed to do it again, as though it's a pulsing thing - weakes, recovers, weakens recovers - but all very subtle, not misfiring or lurching.
As though the boost is opening up a crack which then reseals and the process repeats.
Hope this rings bells with someone!
Ian

outnumbered · Jan 7th, 2012, 14:58

MAF sensor a posability.

artiedtke · Jan 8th, 2012, 14:11

Quote:

Originally Posted by outnumbered

MAF sensor a posability.

was thinking same thing. Try giving it a clean, but its probably dying if its original at that mileage.

BillB · Jan 9th, 2012, 19:35

I agree about the MAF sensor - your one is electronic. It should be regarded as a maintenance item after 150k imv. Regards.

Ian HT · Jan 10th, 2012, 22:44

Thanks for your replies. I'll investigate the MAF...

I "tested" the car again on the Great Glen by-pass (Leicester to Market Harborough) and given plenty of road there is time in 5th gear to feel the slight drop in power "pulse" - power drops a fraction for a second, comes back for 3 or 4 seconds, drops again and so on.

I'll report if cleaning the MAF helps.

Ian

Jan 7th, 2012, 11:10	#1
Ian HT VOC Member Last Online: Apr 10th, 2024 08:20 Join Date: Dec 2001 Location: Syston	Flat Spot? Hi All, My V70 TDI 1999 (manual, 167,000 miles) has developed a quirk...It is not a problem yet as it drives corectly 99.9% of the time. However, if I accelerate hard - say, speeding up on a slip road onto the bypass - when in 3rd and 4th I notice that the hard acceleration drops off just a fraction for a second then goes back to normal. It is a very faint effect so that a passenger probably wouldn't notice, but it is there: repeatable if I slow a bit and put my foot down again. No funny noised noticed (except sometimes a slight short growl when lifting off to change gear 1st to 2nd and 2nd to 3rd, which I thought was the metal strip on the back of the engine top cover vibrating). Has anyone had this and diagnosed it? I would be very grateful for ideas as a starting point... Happy New Year to all, by the way! Ian

Jan 7th, 2012, 13:32	#2
artiedtke Just one more thing... Last Online: Jul 10th, 2020 14:44 Join Date: Dec 2008 Location: North Wales	At around what rpm's ??? Mine is quite gutless until 2000rpm then it flies.... __________________ '98 V40 2.0T B4204T - died... '96 855 2.5 TDI D5252T - 255,000 miles "Diesel without turbo is like a woman without boobs... sure you can drive it, but there's always something missing."

Jan 7th, 2012, 14:58	#4
outnumbered Lunatic from Wakefield Last Online: Apr 16th, 2023 06:33 Join Date: Dec 2004 Location: wakefield	MAF sensor a posability. __________________ 2012 volvo xc90 Executive Buccaneer Bermuda 2021

Jan 7th, 2012, 14:53	#3
Ian HT VOC Member Last Online: Apr 10th, 2024 08:20 Join Date: Dec 2001 Location: Syston	Hi -mine is nothing special until around 1900 rpm then flies. That's normal - it has always ben that way! I went out this morning and tried again - when pulling well in say 3rd gear, around 3000 rpm there is a slight lull before it regains full strength. It then seemed to do it again, as though it's a pulsing thing - weakes, recovers, weakens recovers - but all very subtle, not misfiring or lurching. As though the boost is opening up a crack which then reseals and the process repeats. Hope this rings bells with someone! Ian

Jan 9th, 2012, 19:35	#6
BillB VOC Member Last Online: Apr 24th, 2024 13:58 Join Date: Dec 2002 Location: Bristol	I agree about the MAF sensor - your one is electronic. It should be regarded as a maintenance item after 150k imv. Regards.

Jan 10th, 2012, 22:44	#7
Ian HT VOC Member Last Online: Apr 10th, 2024 08:20 Join Date: Dec 2001 Location: Syston	Thanks for your replies. I'll investigate the MAF... I "tested" the car again on the Great Glen by-pass (Leicester to Market Harborough) and given plenty of road there is time in 5th gear to feel the slight drop in power "pulse" - power drops a fraction for a second, comes back for 3 or 4 seconds, drops again and so on. I'll report if cleaning the MAF helps. Ian

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