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Discussion Starter #1
1998 Golf Tdi 90hp

Hello folks. New to the site and I hope that there maybe some info here to help me.

I have just bought a real bargain, 1998, 2 owner 38,000 mile with full VW history. New cambelt at 17,000 because of age. It is in perfect condition and I am extremely pleased.

BUT

It drives very smoothly and no patchy feeling on the power. I have covered 300 miles on half a tank so economy is not in question.

It doesen't feel as thought there is a turbo on the engine at all. I am new to the engine but if the turbo is working it is not noticeable. I have of course checked and it is what it says namely a 1998 s tdi 90

The condition of the engine bay is like new and all the pipe work appears to be in excellent order

Any thoughts anybody?

Thanks in advance,

Jpd
 

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Wow, 38,000 miles on a 98jaw drops

A few questions: The UK models were typically a year or two ahead of the US. Is this a mk3 or mk4 (4th generation)?

What engine code do you have? Can you take a picture of the engine bay with the plastic engine cover off?

Take a look through the low power checklist: http://www.myturbodiesel.com/1000q/multi/low-power-fix-TDI.htm

It's probably not related to the low mileage but could be related to age: rotten vacuum lines, etc. If you're still stuck or fix it, please post a follow up. It should feel quite lively even with only 90 hp.
welcometomyturbodies
 

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Get a code reader or vcds/vagcom, my neighbours car's having a similar issue and it's the maf that's bad but I wouldn't have found out without the scan.:)
welcometomyturbodies

Pretty sure that's the first of the Mk4 chitty but not 100%
 

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Discussion Starter #4
Thank you for the response Chitty and Seatman,

It is definitely a Mk 4 and definitely a MK 4 S TDi 90. I will take a look down the check list and come back to you.

Thanks again.
Jpd
 

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Hi Chitty,

I bought an Autel scanner to establish fault codes.

I ran the diagnostics and it brought up only 1.

It reads:

01237 -159 KWP1281
Fuel shut-off valve (N109)
sporadic - open/short circuit

Now, this means very little to me. Does it seem like a small problem or could it be expensive?

Bear in mind that the car ( 1998 39,000 mile MK4 S TDi (90hp) ) drives perfectly, very smooth, in fact like new, except it feels like there is turbo.

PS last full tank mileage check shows 61mpg.

Thoughts?

J
 

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That is the fuel shut off valve on the injection pump. There is probably bad wiring to it or corrosion on the contacts. I don't believe that it's related to the low power problem.

Log the air flow sensor's requested vs. actual data.
 

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Hi Chitty, I appreciate your rapid response.

"Log the air flow sensor's requested vs. actual data."

Consider me an imbecile, how easy and how do I do that?

J
 

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I am not familiar with your scanner but bascially you have to find the measuring block or data output where it shows the MAF sensor. Compare the sensor value to what the computer wants. If there is a large difference there is something causing the sensor to be bad, usually it's a bad sensor.

See the low power FAQ article for some screenshots and more ideas, that's why they are Frequently Asked Questions :)
 

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Discussion Starter #11
Thanks for the response and input CCBB.

I am from a technical background but VAG engine management systems are new to me. I am from a civil engineering background.

I obviously need to do some more homework so that the info you are imparting makes more sense to me.

Regards
John
 

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Discussion Starter #12
What would you suggest Seatman. How much is a new relay - I see around £20.

J
 

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Do you know if it's a wastegate turbo or vnt on yours? I know the year before was a wastegate, if it is a wastegate it might well be stuck open which would kil the boost and the fact it's done such a low milage suggests it hasn't had a good thrash. You could try doing a rough 0-60mph in it, it should be about 12ish seconds, if not then I would say it's certainly lacking in power. I don't think I would throw any money at it yet, I think it needs further investigation and a right good thrash to free it up.:)
 

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Discussion Starter #14
I take on board what you say. I will give it a good run today and see what times are thrown up and come back to you.

Thanks
Jpd
 

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Hi,

When the car got warm I tried a 0-60. It was very slow indeed. Post 20secs. The early revs are fine but it seems to have a distinct lack of power after 3000 dying off top end. It fails to reach higher revs the further up the gear box I go.

I do not know how to tell the difference between a wastegate or VNT.

Thoughts?
 

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1998 jetta tdi

New to site, hopefully can find info that will pinpoint my problem. Problem started at 150k, car went into limp mode when going up long hill. P1550 engine code set. Mileage continued to be 41 to 42 mpg. Not a problem, learn hill management and kept driving car. At 200k, car was in limp mode all the time, p1550 code set all the time. Now theres a problem. Work that has been done so far: 1) replace all vac lines associated with turbo and egr (and inside ecu) 2) "cleaned" exhaust system (lets just say that several parts were full of soot and they have been removed), end result, exhaust system is free and clear. 3) cleaned intake manifold, 4) wastegate lever on turbo was "frozen", had mechanic clean/free-up wastegate. End result, still getting p1550 code and still no power. Don't know what fuel mileage is, i keep killing bat pwr to reset computer and this screws up trip odometer. I will check mileage soon. Have purchased (not received yet) computer cable for self diagnostics. Next step, check n75 valve & maf sensor for proper operation, unless someone has a better course of action.
Thanks,
 

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try putting a can of combustion chamber cleaner through the intake ( possible valves carboned up restricting air flow)
 

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Hi,

When the car got warm I tried a 0-60. It was very slow indeed. Post 20secs. The early revs are fine but it seems to have a distinct lack of power after 3000 dying off top end. It fails to reach higher revs the further up the gear box I go.

I do not know how to tell the difference between a wastegate or VNT.

Thoughts?
Have you checked the inlet manifold isn't clogged? There's a good chance that it's been babied and as a result the intake might be needing a clean out. Have a look at this faq, don't worry if it looks different, the principles are the same.:)

http://www.myturbodiesel.com/1000q/a3b4/clean-intake-manifold-tdi.htm
 

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Thanks, is this (combustion chamber cleaner) something that I mix with the fuel? or do i shoot it into the manifold (after removing air duct)?
 

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I'd be careful putting any liquid into the engine. Dealers used to decarbonize intake manifolds this way but sometimes it damages the engine through hydrolock or big chunks of carbon breaking off. Plus, you wrote that you already cleaned the intake. That is where most of the buildup is.

I've done seafoam treatments on gas engines and it does help with idle slightly if it's rough due to carbon buildup. A TDI has much higher compression...
 
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