# 2.5 Loss of Power When Accelerating and Hot



## Juano007 (Apr 22, 2003)

Any ideas????

I have an 07 Jetta with the 2.5 I5. After I drive for an hour or so in the heat I lose power. It seems to be a direct relationship to the power that is lost and the amount of throttle input. If I step on the accelerator hard enough when this starts happening I will kill the engine, but can start it back up immediately and gently accelerate again, but only slowly and with some clutch work. When this happens I cant go up hills, but I seem to be able to maintain a constant RPM on level ground. If I let it set for a few hours it will drive down the road fine for another hour or so or until it heats back up. The temp gauge is not showing the engine is overheating, my fluid levels are good and the vehicle has never had major issues. The spark plugs were changed about 6 months ago. I can drive for hours if its not hot outside or I'm not going up hills. 

Anyone with ideas please PM me or even text me 970-412-1956 I need to fix this soon but don't know where to start. Searched the forms and haven't found an answer. New belts, pulleys and fuel filter will be in this weekend, but not sure if those will help....

Thanks
j


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## rommeldawg (May 25, 2009)

how is rpm relating to the mph indicated by the speedometer, is the clutch worn out and slipping?


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## Juano007 (Apr 22, 2003)

It's normal. No evidence of the clutch slipping at all. I wish it was so I knew where to start.


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## mjb8482 (Mar 4, 2008)

Definitely check for a post maf vacuum leak. Ive blown charge pipes before and my car acts the same way as you describe. Good luck.


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## rommeldawg (May 25, 2009)

and there is no cel on?


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## Juano007 (Apr 22, 2003)

No CEL... If I had a vacuum leak wouldnt it do this all the time not just when hot? I cleaned the MAF real good today, that didnt help. Someone suggested the fuel pump might be bad? But everything I read says the FP rarely goes out on the MKV. And again, why only after an hour of driving? Wish my local Colorado VW dealer wasnt such a scam I would just take it in. They tried to sell me a timing belt for $900 last month. A part the 2.5 doesnt even have. Told me the belt was looking worn, I called him back and reminded him the car has a timing chain not a timing belt. 
Tools.


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## Dena Dubber (May 8, 2010)

Any luck finding the problem? Im having a problem like this also. I installed the IE sri with the UM tune and the car accelerates great and is very fast. the problem is I cant drive the car non aggressive, when i try to accelerate without down shifting and stepping on it the car shuts down into limp mode and the epc light comes on. The CEL came on and the code said ecm processor failure when scanned at auto zone but VAG COM didnt show anything. I scanned it with a Snap On scanner and it showed throttle control module #2. Id really like to figure this out without throwing parts at it.


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## rommeldawg (May 25, 2009)

dubber you need to create your own thread as your issue is more likely to be your tune or re-adapting of tb.


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## rommeldawg (May 25, 2009)

Juano007 i know you have stated the cel was not on but have you scanned the car anyway preferably with vcds if you can


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## le0n (Jun 12, 2013)

Juano007 said:


> No CEL... If I had a vacuum leak wouldnt it do this all the time not just when hot? I cleaned the MAF real good today, that didnt help. Someone suggested the fuel pump might be bad? But everything I read says the FP rarely goes out on the MKV. And again, why only after an hour of driving? Wish my local Colorado VW dealer wasnt such a scam I would just take it in. They tried to sell me a timing belt for $900 last month. A part the 2.5 doesnt even have. Told me the belt was looking worn, I called him back and reminded him the car has a timing chain not a timing belt.
> Tools.


fuel pumps can act up after they are warm/heated up. it's just like any other electronic components, cam/crank position sensors do the same thing once faulty. on the mkivs the coolant temp sensors act up and even send signals to the ecu that in turn end up cutting fuel.

as stated, get it scanned with vagcom, it may save you some hassle; it may not. but it would be a good place to start.

also, have you been changing your fuel filter every 40k miles?

sad and sucky about the 'timing belt' sales pitch.


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## FL 2.0L (Aug 1, 2002)

Same issue with my 2.5L ('06 Rabbit with nearly 127K) today. Felt like the start of a faulty fuel pump. It's never hesitated before, but today, nearing an empty tank, I went to accelerate away from a stop sign, left across traffic, and it just cut out. Had to get off the pedal and slowly limp it up through the gears. Happened at the next 2 stops signs. It was good after that. I made it to the gas station and home, accelerating slowly and quickly, without any hesitation. No CEL. Going to get the scan tool on it now, but I don't anticipate any codes will show.

EDIT: No codes.


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## Juano007 (Apr 22, 2003)

*Fixed - Fuel Pump was bad.*

Vagcom showed no codes, I had it plugged in at the shop at the exact second the engine was acting up and it showed nothing. Fuel pump got replaced today and its working perfect. Fuel pump seems to have been the problem. Only thing now is I chewed up so much clutch milking my RPMs to get it home when it started going out, I will soon need the clutch replaced. 

Thanks for all the help and replies.


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## FL 2.0L (Aug 1, 2002)

Thanks for posting your solution. I have a new pump on the way.


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