Very rough idle alh

S

sierra 09

New member
Joined
Jun 30, 2012
Location
northern ireland
TDI
agr alh avf
I have a seat Leon 1.9 tdi alh engine, the problem is when I start it, it will run 100%, but after about 10 seconds it starts to idle very rough, shaking the whole engine and car, anyone any idea what would be wrong? As soon as I touch the trottle it revs smoothly.

Also the car had a replacement turbo just before I bought it.

All help appreciated.
 
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V

Vvarak

Veteran Member
Joined
Aug 29, 2003
Location
Ajax (Toronto)
TDI
2013 Jetta
I had this very same problem in my 2000-ALH-Jetta.
Very rough at stop lights and touching the throttle stopped it.
Everything else was fine for me (cruising, etc.).

I checked the timing with VCDS and it was fine (a little advanced).

So I checked the IQ at idle and noticed I was around 1.4mg/R. (normal is 3-5).
So I lowered my IQ adaptation value a bit...I think it's at 32700 now (default is 32768).
And now my IQ is 3.0 at idle. Took a few tests to get it right, but it's very quick to do.

Idle is great now.
Hope this helps.
 
M

Milad

New member
Joined
Mar 26, 2008
Location
Bosnia
TDI
Golf A4 ALH
I have been struggling too with ALH rough idle for some time now.
Mine is 2002 ALH with 300k, recently it started to idle rough, it was like a gasoline engine misfiring, with no other symptoms, power loss, smoking or anything else…
First thing I suspected was DMF so I decided to replace it. Bought an original Sachs Clutch Kit for DMF (A4) and ventured into the rough idle saga.
When taking the old clutch out I noticed that the flywheel has indeed seized, so I replaced it.
Started the engine with enthusiasm, and after 5 – 10 minutes the rough idle started again.
Since the smooth idle control (IQ) was reading from 2.8 to 4.8 mg/str erratically only on idle, and it would smooth out on higher revs, next thing I did was to replace the needle sensor – third nozzle from a working TDI ALH, and nothing. Then I proceeded to replace the Crankshaft Position Sensor with no positive outcome.
So now I acquired a very good IP, from a low mileage, but wrecked TDI, and replaced that too, and surely, NOTHING! Same rough idle with timing dead on and not jumping up or down at all on the graph. So I replaced all of the nozzles with the same result at the end, it idled rough. Also I checked the MAF and the temp sensor and replaced the throttle paddle.
And now I was starting to suspect it was the valves – soot build up underneath one of the valves. Checked the compression it was 30 bar (435 psi) with a professional gauge on all four cylinders on warm engine.
So at that moment, I gave up, set down and had a nice cold beer and pondered how it would be nice to set the damn thing on fire! Then I remembered that couple of months earlier I had a malfunctioning oil level sensor, the one on the oil pan, and it was just about that time it started acting up, so I figured I’ll unhook it for the sake of it, it was the last sensor on the car.

And, voila just like that, it started purring like a kitten, when I would plug it back in it would start idling rough again and vice versa. And important to say after unplugging the oil level sensor the IQ was steady, on the 4.0 mg/str on idle.

Sorry for the lengthy post, but this was my awful experience and it does not cost you a thing to try to unplug the oil level sensor.
The sensor was made by Febi Germany.
 
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S

sesap

Member
Joined
Sep 24, 2015
Location
usa
TDI
98 twin turbo manual conversion Jetta
Hello, might had as well revive this thread with an added question. I have an 01 alh in a Jetta with an automatic trans. What I would like to know is I have a reader cable from an older car (97 ahu) the cable is a cheap knock off numbered kkl vag-com 409.1 In past I’ve only used it as a code ready with free software download. Can I use this to adjust fuel quantities at idle to prevent surging ( as explained above)?? If not what do I need? And as anything on a major budget, I mean the car is a beater and if a parking light burned out it would be totaled ha ha. Also to add another note my driving style is left foot braking and the safety deal that cuts the fuel (ecu thinking the throttle is stuck) is very annoying, the rough idle makes even worse and I know once that’s fixed 85% of those issues will go away with it I still want to bypass the safety feature so I can foot brake spool and trail brake corners as well. Thanks for any input
 
Nero Morg

Nero Morg

Top Post Dawg
Joined
Oct 19, 2017
Location
OR
TDI
2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
sesap said:
Hello, might had as well revive this thread with an added question. I have an 01 alh in a Jetta with an automatic trans. What I would like to know is I have a reader cable from an older car (97 ahu) the cable is a cheap knock off numbered kkl vag-com 409.1 In past I’ve only used it as a code ready with free software download. Can I use this to adjust fuel quantities at idle to prevent surging ( as explained above)?? If not what do I need? And as anything on a major budget, I mean the car is a beater and if a parking light burned out it would be totaled ha ha. Also to add another note my driving style is left foot braking and the safety deal that cuts the fuel (ecu thinking the throttle is stuck) is very annoying, the rough idle makes even worse and I know once that’s fixed 85% of those issues will go away with it I still want to bypass the safety feature so I can foot brake spool and trail brake corners as well. Thanks for any input
Click to expand...

You may want to start a new thread bud, if the car you're experiencing this issue with is the one you registered on the forum that has a twin turbo swap and waste oil burner, you may have other issues...
 
S

sesap

Member
Joined
Sep 24, 2015
Location
usa
TDI
98 twin turbo manual conversion Jetta
The twin waste oil car is an older 98 ahu car. As stated in this post I’m asking about an 01 alh. The ahu car is still going and lots of fun and since the original register date it has acquired a 12mm pump from a mechanical 4bt engine and custom nozzles There are plans for a new tall deck (custom) block and different head set up while putting the engine in a 93 square body s10 4x4. But back to the other cars issues I got cable registered and I have gotten the surging fixed the egr delete programmed but I’m still at a loss with my left foot braking issues but it’s much more tolerable now that the surging is smoother

Thank you
 
4

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
to be able to power brake it you need to edit the binary file in the ECU. vag com cable will not do it, you need the MPPS cable and a hex editor program
 
BakoTDI

BakoTDI

Veteran Member
Joined
May 5, 2005
Location
Bakersfield, CA
TDI
Jetta, MK7
Milad said:
Then I remembered that couple of months earlier I had a malfunctioning oil level sensor, the one on the oil pan, and it was just about that time it started acting up, so I figured I’ll unhook it for the sake of it, it was the last sensor on the car.

And, voila just like that, it started purring like a kitten, when I would plug it back in it would start idling rough again and vice versa. And important to say after unplugging the oil level sensor the IQ was steady, on the 4.0 mg/str on idle.

Sorry for the lengthy post, but this was my awful experience and it does not cost you a thing to try to unplug the oil level sensor.
Click to expand...
Did you have a CEL for the oil level sensor? I’m experiencing the same symptoms as above but I have not CEL. I just ordered my vagcom again, since it got stolen, so I have to wait to get any readings. So I’m just wondering if I can expect any ECU indication about the sensor. Thanks for the feedback!
 
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