a4 1.9 tdi power loss

[daz2617]

hi all , i need some help with my 97 1.9 tdi a4 , i have owned it since 2 years old and has been the best car i have ever had ,,
its first problem has arisen !
when you start it , always starts instantly whatever the weather it revs high at about 1100 rpm , if you stop when its warm it does the same every time you start it .
it drives very well up to around 2500 rpm , overtaking or going uphill it goes into limp , switch ignition off and on and ok until the next hill .
reading some of the other posts i have taken the turbo off and cleand it , checked the actuator is ok , cleaned the intake manifold , checked for vacuum leaks , checked the vacuum solenoids , changed the water temp/management sensor ,and all ok , even got a new maf sensor and ran worse with this on so put the old one back on .
im now a bit stuck ??
thanks
darren

[Gazwould]

Over boost limp mode caused by sticking vnt turbo , the famous Mr Muscle oven cleaner !

[FLAPPERJACK76]

What engine code is your vehicle Ahu? If so you don't have a vnt turbo. Afn then yes you have. You have missed something. Start again. I been in the same position as you a long time ago. Have you replaced all the vacumn hoses? Use the silicone 3mm id stuff. I have used cheap replica hosing before from motor factors the external fabric stuff only to find this stuff splits in just a few month's. Start there 1st do you have any fault code's. Have you changed your air filter? Is the oxidation catalyst blocked? . If it's vnt it can take a lot of cleaning I had to do it 3 or 4 times to get it right.

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[daz2617]

the engine code is afn . i have replaces the flexible parts of the vacuum hoses , and checked the one to the ecu .
fault codes are , coolant sensor ,intake air temp sensor ,fuel temp sensor .
i replaced the coolant sensor , and the sensor on the air pipe at back of engine , presume that was the temp sensor .
new air and fuel filter fitted
i dont think the cat is blocked as it runs great up to 2500rpm then struggles , but if you switch off and on the ignition it goes fast again , up to 90 easily ?

[FLAPPERJACK76]

Strange as it sounds like an over boost issue with no over boost fault code. How about the vacumn hose to the ecu? Is there oil in this pipe that's now in the ecu?

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[daz2617]

hi , when i took the pipe off the ecu it did look a bit black on the ecu like oil was there

[daz2617]

hi , i did the mr muscle cleaning , no change , the turbo accuator moves freely up and down , checked with the engine running by taking pipe off accuator and when no vacuum the arm drops down , arm comes back up as soon as put the vacuum pipe back back on , at idle , is this correct ?

[FLAPPERJACK76]

Yes that's ok. Is it moving enough though.

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[daz2617]

it does move a long way up and down , a couple of centimeters i would say

[FLAPPERJACK76]

Yours is strange as those symptoms you should be getting an overboost or charge pressure deviation fault. Have you tried a new n75 solenoid valve. You say you have a live and earth but it could be stopping intermittently.

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[daz2617]

i did swap it for one i had as a spare , i checked it worked on a battery and clicked ok . maybe worth getting a new one ?
will oreder one tomorrow and try that
thanks

[FLAPPERJACK76]

I would remove the egr pipe on the manifold work wd40 down the hole whilst moving the vnt up and down. As much as possible till your happy. Then change all the vacumn hoses. If the turbo is over boosting the ecu will shut n75 down then if you turn ignition off then on this re energises n75 and the power comes back. So its always been a case to me is it the hoses or the turbo or n75? . Just a matter of working out which one.

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[FLAPPERJACK76]

Another thing any black smoke out of the back? If so check all the charge pressure hoses especially that small in length one on the right side of engine

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[daz2617]

thanks , there is no smoke when driving . i will get some new vacuum tube and order a n75 and see how it goes , if not i will take the turbo off next weekend and give it a damn good clean out !
thanks for your ideas

[FLAPPERJACK76]

Ebay is good for the silicon 3mm internal diameter stuff. Just buy it off someone who has good feedback and sells a lot of it. Maybe some turbo treatment to go in the fuel tank from Forte or similar is worth a shot


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[daz2617]

ok thanks will do

[minny]

Funny enough, came here to make a similar post.

On slack hill, very steep, over taking it suddenly lost power and drove like my none turbo a4, turned it off, when I turned it on again everything was fine for weeks.

Doing exactly the same thing on exactly the same hill the exact thing happened again. So I stoped at top of the hill, turned off and on again and it was fine.

I was worried it was the turbo going faulty, but it looks like it could just need a clean.

Is the hill significant or is it just becasue the car is working harder, it's fine every where else.