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Discussion Starter #1
2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" post!

Good afternoon,

I'm after some help from the TDi experts on here.
My van has been suffering with a scattered timing problem for a while now.
I asked about the issue on here a while back and we put it down to the fuel pump.

Well as it still drove fine and is still ok on fuel I ignored the problem for over 6 months.

Over the last week I have been fitting a replacement pump, just finished and it hasn't solved my problem.

So the problem
Is that the timing plot on the TDi timing graph on vagcom is not stable. The timing fluctuates enough to spread over the entire graph.
See video link below

http://i251.photobucket.com/albums/gg309/ryanbob202/3d2cf26c.mp4
http://i251.photobucket.com/albums/gg309/ryanbob202/7ab21b0e.mp4

I'm completely lost right now.
My only thought is that a sensor has failed or something....
How is the pump timing measured? Could it be something to do with the injector that's instrumented?
I originally thought it could be to do with the wobble on the camshaft injection pump sprocket - but I don't thin it is any more.

Cheers very much for any help
Ryan
 

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Discussion Starter #2
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

So checked and the resistance of the injector is around 115 and as such is ok I think.

The only fault code appearing is related to the coolant. Not other codes.

Cheers
Ryan
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

So checked and the resistance of the injector is around 115 and as such is ok I think.

The only fault code appearing is related to the coolant. Not other codes.

Cheers
Ryan
I would replace it without a second thought bud, it sets the timing advance based on the engine temperature, its not just for the gauges T:T:
 

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Discussion Starter #5
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Well I should point out that these running problems, loads of smoke cold, lumpy though lower revs. Have o my been around post belt failure rebuild around 6 months ago. And I've had that. Coolant sensor problem since I got the van.
Have replaced the sensor once but it didnt cure the problem as I assume it's a broke. Wire somewhere but couldn't be fussed to find the problem!

Given that the van ran ok with the coolant sensor error previously it would suggest that this isnt the cause of the scatter. Correct me if I'm wrong though!

Belts installed and tensioned correctly yes. You can see one of them in the vid.

Cheers for the replies!

I assume the sensor injector feed the pump timing to vagcom. As with the sensor injector disconnected it only plots a couple of points on the timing graph at around 38 for both of them.
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Might be worth posting this on the tdi club forum. What they dont know about all things tdi isn't worth knowing!
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Fuel temp sensor wants looking at first.

Then crank position sensor, then fuel pump then needle sensor.

IMO - its the fuel pump.
 

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Discussion Starter #9
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Ayeup. Cheers for the replies.

Fuel temp sensor I hadn't noticed!
I didn't think it would be the crank sensor as its vertical scatter not horizontal...

I don't think it's the fuel Pump, seems like a unusual problem, and to have it on two separate pumps seems far too unlikely.

Waiting to be made a member over on TDi club.

The sensor injectors resistance seems ok from one of your previous threads I found Rake, but I wonder if it's working just erraticly.

Cheers again for the help gents, really want this fixed!!
Ryan
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

How is the balance of injectors mate?
Your ecu may be trying to compensate for a problem injector.
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

I would. Heck the injector resistance pin to pin and also pin to ground (injector body)
Let me know the readings both hot and cold.

That fuel temp is a clue. When these go they make the timing unstable. I lay odds that it's the temp sensor in the pump.

I would be very surprised if the injectors are the problem.
 

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Discussion Starter #12
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Cheers for the advice gents. Been out riding my bikes rather than crawling around under the van for once!!

So when I arrived in Shropshire today I took a picture of every page of vagcom!








I'm so convinced that this isn't fuel pump related! It's just too unlikely that two different pumps have this exact same, fairly unusual, problem.

As you can see the read outs on the measurings blocks the rule temp is more reasonable.

The hot/warm reading for the sensor injector was around 115 ohms.

Cheers again for the help, much appreciated
Ryan
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

My thoughts are that the engine needs to be above 85C, well it does for timing reading.
I wasn't able to download video so maybe you had it up to temp. for those readings.
 

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Discussion Starter #14
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Right I'm gonna sort out the coolant temp sensor commectioms this week.
Take it from there.
The engine was up to temp, either way it wouldn't effect my symptoms.

Can everyone else see the vid??
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Your fuel temp is way off in the vag scope screen.

Choose to ignore if you like but this is exactly the symptoms of the fuel temp sensor in the pump fella.

MAF is off too.

Pot 4 injector not good either - deviation of 2.5 and the injector is duff.

Engine has to be at 90 to take readings.

Coolant temp seems ok.
 

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Discussion Starter #16
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Two threads is gonna get confusing!!

I'll start off by saying that the poor fella has covered over 320000 miles now so there's bound to be some tired parts!!

MAF sensor the same erratic timing is produced with it disconnected
Will disconnect fuel pumP sensor soon and see if that could be causing it.
Coolant temp seemed a little low to me, but then I assume diesel run cooler than my a-series used to.

Don't know if I said this or not but disconnecting the sensor injector stops the scattered erratic timin, though I assume this is expected as the reading from that injector is one of the things used tO plot points on the graph?

Cheers
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

The NMS tells the pump and ECU where the commencement of injection is so yes it is possible as its part of the chain.

Did you get the readings I suggested from it ?

Need to get that fuel temp on vagscope again. It did say 132 degrees....not F was it ?



Also known as the G81, this sensor has a direct effect on start of injection.
A bad sensor can make your timing unstable.

(this is not my hand !)
 

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Discussion Starter #18
Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Cheers, been working On the bike tOnight, so not had anytime to check out.

Will try to find some time to get on it tomorrow. Hate taking the figgin belly pan off!!
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

Cheers, been working On the bike tOnight, so not had anytime to check out.

Will try to find some time to get on it tomorrow. Hate taking the figgin belly pan off!!
Keep it off till fixed ;)
 

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Re: 2.5 TDi timing scattered / unstable timing - this isnt a "how do you time TDi" po

ive got same issues
have found a problem broken wire in loom above rocker cover
very small black and white wire looked ok untill i pulled it lightly
but i think because it was broken it causes the temp sensors to brake
waiting for a delivery from gsf
 
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