GT TDI 110 AHF Fault code 17656 P1248

[Gareth041]

Hi all, Gareth here!

I have a 99T GT TDI 110 bhp AHF engined Golf that is sick!

I have the above code and have checked and done the following

(1) Checked codes:- 17656 P1248 Commencement of injection regulation.

(2) Changed No3 injector as told to do so and found it not at fault.

(2) Checked the Pump Commencement valve and it reads 10-20 Ohms as specified ok.

(3) Checked the wire from the ecu-pump, no resistance found.

(4) Also changed the fuel and air filters as a precaution.

Car is as flat as a f#rt, massive diesel knock and very smelly.

Symptoms seem to point to the ECU but my wallet and butt twitch at that thought!

Anybody got any ideas or seen this before? If so your help would be gratefully recieved.

if anyone wants to call my No is 07786 863867, I will ring you back!

Please help as 40mph on the M6 is not funny!

TA! Gareth.

 

[richandhazel]

17656 P1248 is as you say 'start of injection - control difference'

Probable causes are: fuel injection timing solenoid, injector needle lift sensor, fuel level low, pump timing.

Have you tried checking your timing with vagcom? Mine is set at 70 which I have found to be best.
I can give you a test proceedure for the solenoid.

[Gareth041]

Hi Richard.
Firstly thanks for the reply.
I have checked the pump timing with my friend's VAG-COM but I only have the vertical line, no horizontal one?
I have checked the pump/ cambelt timing statically by removing the vac pump and locking it up and it seems ok?
The test procedure for the solenoid would be welcome and any other advice!
Many thanks, Gareth.

[richandhazel]

I don't bother with the graph. Just read the measuring blocks:-

1. Start the engine and let it run.
2. Hook up the Vag-Com® and start the software and enter data block 000.
3. Enter "Basic Settings mode". Read data block 2 and data block 9. If block 9 (fuel temp) is reading 110 then block
two should be reading 70. I doubt it is since the timing is only set to be in the ignition window.
4. Shut off engine.
5. Loosen the three bolts (DO NOT REMOVE THEM!) on the injection pump. Using your trusty large crescent wrench
(or some sort of a wedge) gently and very, very slowly rotate the pump counterclockwise to make the number in
block 2 increase or clockwise to make it decrease. Increasing the value of the number in block two will effectively
"Advance your timing".
6. You will,of course, have to guess at how much you moved the pump. Retighten the 3 bolts , get in and start the
engine and see where its at. If the number is not where you want it repeat the procedure 1-5 until the setting is
where you want on the graph in the bentley manual (sometimes I am glad one of my cars is an A3....)
FYI: Advancing the timing (counterclockwise) will reduce smoke output, increase fuel economy, and make the
engine more rev happy. It will not matter if you are running the .184, .205 or .216 injectors because the #3
injector tells the ECU when injection occurs so the ECU will have all that taken care of.

[richandhazel]

Solenoid test:-

http://homepage.ntlworld.com/richandhazel1/vw/solenoid%20test.pdf

[Gareth041]

Hi Richard.
I have checked the fuel injection timing solenoid and it reads 15 Ohms and near 12 Volts.
The car has plenty of fuel and it is diesel!
If I have checked the pump timimg could it still be the crank pulley as I have heard they slip/ come loose ?
Where is the injector needle lift sensor or is it No3 injector?
Thanks again!

[richandhazel]

My money is still on the timing. It really is very critical and only the slightest movement of the pump pulley is required to make a large change so checking it statically is not good enough. It will get you roughly there but you must use vagcom to get it correct. The 3 bolts that secure the pump pulley are meant to be replaced once you have got it correct as they are stretch bolts. If you don't replace them I would think that there is a danger of them coming loose.

Yes I think it is No.3 injector that has the sensor.

[Gareth041]

Hi Richard.
I will be checking the timing again, via vag-com, next week. Work and family grief has put a hold on anything else so far. Believe it or not but finding a VAG guy up here with even a remote clue is painful.
I totally agree that it sounds timing related but would it still run?
Again my symptoms are as follows,pinking sound(timing!), flat as a f#rt!, lack of torque, nasty smell and pooh economy. The turbo is non existent.
On the vag-com "timing screen" I only get the vertical line , no horizontal. Obviously this is telling me the timing is miles out but does it mean anything else to you? Maybe a sensor down?
As previously mentioned I have checked what you told me and found no fault.
Thanks for your advice and guidance thus far.
Gareth.
P.S. If you are ever up the Lake District let me buy you a beer!