Idle smooth running control

Airliner

Veteran Member
Joined
Jan 15, 2005
TDI
Audi A4 1.9TDi Avant Quattro 2001 silver
Hi.

A friend of mine is thinking about buying a (used) VW passat 2002 1.9TDi 4motion 130HK PD engine (don’t know the engine code, but maybe ATM or something, it’s at least the PD 130HK 310NM engine).

But I scanned the car, and got some “abnormal” (I think) readings from the “idle speed smooth running control”. Even if the numbers are within the limits, I have never seen them this high on any other PD engine I have “scanned”. I have a Audi with a 1.9TDi 115HK (ATJ engine code), and the numbers are very close to 0.

Have a look at this screenshot: http://lundarvollen.com/slett/dyser.jpg
The screenshot is with normal temperature reading on the engine.

Could this numbers be due to a poorly installed timing belt (which has been replaced 3 weeks ago according to the owner of the car), or maybe a partially clogged catalyst when the car has been used for shorter trips in the past ? Any other reasons for this numbers to be “a bit high, even if its within limits” ? Something to worry about, or just buy the car without further investigation ?
 

DPM

Top Post Dawg
Joined
Mar 16, 2001
Location
Newtownards, N. Ireland
TDI
2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
An engine problem causing low compression, or something dodgy about the injectors, is most likely.

How many Kms on the engine?
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
I think the most likely cause is the need to adjust the mechanical clearance to the cam on the PD pumps. It sounds as if they are easily adjusted - just like adjusting mechanical valve clearance on an old beetle.

Some books for some PDs recommend running the adjuster down until contact then backing off 270 degrees. For other PDs the recommended back off is 90 degrees. Some knowledgeable folks think it should be 90 degrees for all PDs - that some of the books are wrong.

They feel that backing off 270 degrees may be the cause of rough transition from running to idle. Excessive difference from one unit pump to another can cause rough idle.

I have not had to adjust mine and have no direct knowledge. Mine run
-.12, 0,-.12,.24.

If you adjust it and it still shows that much difference, it is probably a bad injector - but I would bet on the need to adjust the clearance.

Dan

edited to adjust all of the pumps, not just one.
 
Last edited:

Airliner

Veteran Member
Joined
Jan 15, 2005
TDI
Audi A4 1.9TDi Avant Quattro 2001 silver
Thank for your reply. Sounds like my friend should not buy this car.

It has "only" 160.000 km.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
I would not let this keep me from buying an otherwise good car - but then you have a much larger TDI population to choose from.

I would use this as an excuse to pull the valve cover and closely examine the cam and followers while I adjusted the pump clearances. (Or watch and inspect as the sellers mechanic does the work.) When buying a used PD the potential valve train damage from using the wrong oil is my worst fear.

Or I would argue down the price based on the apparent worst case of having to replace two injectors on the PD. Get a price from a competent mechanic.

Dan
 
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