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TDI 101 Got a simple/basic TDI question? Are you a newbie (new to the forums). Feel free to post your question here.

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Old August 6th, 2003, 05:27   #1
wiezzl
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Join Date: Mar 2003
Location: London, On. CDN
Default Loss of power going up hill

I was recently on holidays in the Maritimes with the family so the car had a little more in it than normal, but not over loaded by any means.
I found that the car would decrease in speed when the cruise was set, but when I put my foot on the pedal with the cruise still on the car would pick up speed.
So it is not a power loss issue as much as the cruise will not maintain the speed it is set at.

Any ideas on what may cause this? and what the fix could be?
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Old August 6th, 2003, 09:36   #2
cattlerepairman
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Location: Ottawa
Fuel Economy: 8.4 l/100 km at 60/40 hwy/city
Default Loss of power going up hill

Yes, a pretty good idea, actually.

What you describe sounds like a symptom of a slowly dying MAF.
You might also notice that your car accelerates smoothly up to about 2700 rpm and then "hits a wall" up to 3100 or so, and after that it pulls up better. Another common sign of a MAF that gets inadaequate.
The good news: Not too difficult to test, self-replaceable, numerous options available.

You will find more info in the TDI FAQ and in THIS THREAD and in THIS THREAD

It is a good idea to have a TDIClub member that has VAG COM to check out your MAF before you start buying parts. Check the list HERE to see if anybody is in your area.
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Old August 6th, 2003, 09:52   #3
Lug_Nut
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Location: Sterling, Massachusetts. USA
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Default Loss of power going up hill

How much did the speed decrease before the right foot override commenced? The cruise works on a basic P.I. algorithm. The amount of fuel is proportional to the variation from the desired speed. The amount of fuel is further modified by a time value with more fuel used when the duration of the variation increases. There is a "dead band", in which small variations from the desired speed do not cause fuel delivery changes.
I notice a variation of + - 3 mph ( + - 5 kph) caused by influences (hills, headwind, drafting) before the cruise reacts and consider this variation to be "normal".
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Old August 6th, 2003, 09:55   #4
wiezzl
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Location: London, On. CDN
Default Loss of power going up hill

The loss of speed was noticable 10-15 KPH before I hit the right foot over ride.
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Old August 6th, 2003, 10:00   #5
wiezzl
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Location: London, On. CDN
Default Loss of power going up hill

I think you may be right
I've had some dead spots in my power
I've removed the MAF a couple of times now and cleaned it, and notice a marked improvement in the power with less or no dead spots.
I will have a look for someone the London, ONT area that has a Vagcom so I can check it before I run out and buy an expense MAF from the dealer.
Thanks for your help
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Old August 9th, 2003, 11:32   #6
dieselUFO
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Default Loss of power going up hill

Or, instead of the dealer$ check out the Pierburg MAF here Impex.com
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