GT TDi 110 Idle problem

I have just bought a Golf GT TDi 110 and I have a few issues. When driving round town stopping at traffic lights about 50% of the time the engine drops to almost 800 rpm then hunts up and down. The other main issue is a whistle for a split second when the turbo is boosting. Any ideas much appreciated.

Thanks

*bump*

I think I have solved the whistle problem. At some point in the past the plastic tube just before the EGR must have blew off the intercooler and hit the power sterring pump pulley. The big hole this left was fiendishly repaired using about 3 rolls of insulating tape. I have fiber glassed it up, so fingers crossed.

BTW Anyway to increase the idea speed about 20rpm?

My problem has gone from bad to worse. See the below faults.

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Saturday, 27 October 2007, 23:27:49
VAG-COM Version: Release 409.1-US

Control Module Part Number: 038 906 018 BM
Component and/or Version: 1,9l R4 EDC 0000SG 2115
Software Coding: 00002
Work Shop Code: WSC 31414
1 Fault Found:
17970 - Quantity Adjuster (N146): Upper Limit Reached
P1562 - 35-00 - -
---------------------------------------------------------------------------


Wednesday, 31 October 2007, 22:38:29
VAG-COM Version: Release 409.1-S

Control Module Part Number: 038 906 018 BM
Component and/or Version: 1,9l R4 EDC 0000SG 2115
Software Coding: 00002
Work Shop Code: WSC 31414
5 Faults Found:
01282 - Intake Manifold Flap change-over Valve (N239)
31-00 - Open or Short to Ground
17957 - Shareware Version. To Decode all DTCs
P1549 - 35-00 - Please Register/Activate
17849 - Shareware Version. To Decode all DTCs
P1441 - 35-00 - Please Register/Activate
17660 - Cold Start Injector (N108) Open or Short to Ground
P1252 - 35-00 - -
17970 - Shareware Version. To Decode all DTCs
P1562 - 35-00 - Please Register/Activate
---------------------------------------------------------------------------

Looks like pump problems, or at least the wiring to it. Is the connector good and tight? Or has someone been disconnecting things in an attempt to faultfind?

Have a llok in Vag-Com, tell us what the IQ is at idle. Not sure which group it's in, a search will tell you all you need to know. Search under "hammer mod"...

DPM has something with regard to the hammer mod! To me it seems someone has tried already! your quantity adjuster is a thing inside your pump that alters fuel quantity when the "hammer mod", pump top is moved back and forth to adjust quantity. The hunting up and down is a characteristic of a bad adjusted hammer mod and or vag-com adjustment! (or faulty pump) unfortanatly you need the full vag-com licence to alter these things. you can try the hammer though, has someone been playing with your car trying to stop your bad idle? I would worry about the other code's later! just clear them.

No, a little old lady owned the car before me. Re the pump, I took the top off to check to see what type of fuel temp sensor i had, but that was after my idle issues anyway. I have not touched the wiring at all, and the yellow paint seal was on the triangular bolt head before i removed it.

In the hammer mod it talks about checking a value in vag-com, trying to get it to 3.6 / 4.0. I take it that has some realation to what the pump is doing. ie I could check that value first and see if it needs adjusted? or not.

I hope I don't come across too stupid, I would have said i was fairly up on car mechanics until I started on my VW diesels.

Thanks for the info and help guys!

I could have sworn I saw a new post in this thread before I left work. Am i wrong?

No your not going mad. I removed it after going back and reading the whole thread again, I felt I was confusing things a little!

Okay, I think I remember it anyway.The rough idle started before I went anywhere near the pump. I read a thread by mcbrew about the fuel temp sensor failing and causing the quantity adjustor error. When I ran VW about a sensor they said my sensor was in the fuel line between the filter and pump. Which it isn't, but I took the top cap off the pump to confirm that mine at least looked the same as mcbrews.

I have VAG-COM and will probably buy the full version not that I have three vw diesels. Can I use it to adjust (hammer) the pump into shape?

Go on to vag-com and see what your IQ number is (when up to temp) it's in m/blocks, your bad idle could turn out to be anything and compleatly unrelated to your IQ, Is your car still hunting? you do know removing your pump top knocks things off all over the place. yes your fuel temp sensor is in the pump, the PD'S have them in the fuel line.

No I didn't, was only following the guide. If i had, obviously I wouldn't have removed it. It doesn't hunt all the time. I'd say about 50% of the time either hot or cold. And it hasn't got any better or worse since I was at the pump. It's 11:23PM in the UK so i'll plug in VAGCOM tomorrow and post results. Thanks for your help DERV-NERD.

Okay, Plugged in the other day when the car was idling and the IQ read 3.4. So I tapped the fuel pump and got it to about 4.6. Car seemed to drive much smoother. However I left the car for a day and went back to it and it started the lumpy idle again. I went to get vag com and the car idled clean again, but now the IQ was at 7.2.

Anyone have any ideas? FYI the fuel pump was botled down real tight and so it didn't move.

Pinknoise said:

Okay, Plugged in the other day when the car was idling and the IQ read 3.4. So I tapped the fuel pump and got it to about 4.6. Car seemed to drive much smoother. However I left the car for a day and went back to it and it started the lumpy idle again. I went to get vag com and the car idled clean again, but now the IQ was at 7.2.

Anyone have any ideas? FYI the fuel pump was botled down real tight and so it didn't move.

Click to expand...

Your IQ wants checking when the car is at full temp only! any difference in temprature will give you a different reading everytime. Try this: Get your car to full temp , see what your IQ is at idle (should be 3 to 4) do the hammer mod up untill about 8! if your idle is still lumpy at any value upto number 8. knock your IQ back to in between 3 to 4, and forget about hammer mods, your fault may lie elsewhere. intake clogging maybe, have you checked this?

I got it to somewhere about 9, idle seems good for the most part. I did discover that it only idles rought when braking to a stop with the clutch in. Once the car has stopped idle returns to normal, even if my foot is still on the brake. With the IQ at 9 it stutters for a split second then idles smooth.

whats the power like at 9? I owned an audi a4 avant for a few years (same engine 110) I tried all sorts to get rid off my bad idle but ended selling it like that. and guess what, my newer car is starting to get moody now. the idle on these cars can be a real pain in the arse. you obviously know your stuff! just keep playing you'll get there in the end.

Power is down, due to over fueling i would imagine. Wonder if I can up the boost somehow.

Still thinking about it, its very strange how it does it under braking but not when stopped.

There is something related to the "brake switch" and a bad idle!
(do a search on it) your best bringing the IQ back down to retore your power. whats your mileage? maybe it's time for an intake clean!

140000 Milles. Intake looks okay, but I havn't taken it off to check properly. Could it be timing related?

you usually notice a mpg issue when the timing is out! is it or was it doing ok mpg wise before you played with the pump top?

MPG is fine, before and after pump playing. I'm just trying to figure out if the idle is to do with timing.

Hi, increasing the IQ value reduces the amount of fuel , which is why you get a power drop , I have a mk4 gttdi too which has always had the same symptoms, i just ignore it, you can adjust the iq up in vagcom too without having to do the hammer mod, theres not as much adjustment though.

sounds like a governor spring is weak or broken. possible flyweight also.

in an electronic pump?