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Discussion Starter · #1 ·
Hi,

I am new to the forum and looking for some advice with some problems I am having.

I have a 2005 Golf MK5 2.0 TDI 140 which has a rough idle only when warm. The revs are not fluctuating but the engine surges every few seconds. There are no problems at all when cold and the car drives well when warm apart from this. The car also takes a lot longer to start when warm, but does eventually start.

I bought the car with 94000 miles, drove it home for 100 miles and took it for a service. I noticed the problem as soon as it returned from service but don't know for sure if this problem existed when I bought it , I didn't notice it. The garage I took it to said the fuel filter was filthy and contaminates may of got into the fuel line when they serviced it. I took it back and and they cleaned the injectors but this didn't fix the problem. I now have 103000 miles and the problem still exists.

Any help or advice would be really appreciated.

Thanks.
 

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Any computer scanner will say if there is any sensor faulty,
Coolant temperature sensors and cranks sensors can cause these type of problems, they record a fault code but will not put a light on the dash.
It could also be something like EGR being blocked etc.

If it's a repeatable fault you can rule of fuel filters etc.

How did your garage diagnose that it was injectors?
 

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Discussion Starter · #3 ·
Thanks for the reply. There are currently no fault codes on the ECU when checked with VAGCOM. The glo plugs have also been replaced recently as two were faulty.
 

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Discussion Starter · #4 ·
Sorry - to answer your question; the garage cleaned the injectors as a matter of course but it made no difference.
 

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crank sensor, battery, or 109 relay.

Unplug the coolant temp sensor and start the car when it's warm. How does it start and run? Report back with your findings.
 

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The crank sensor would have stored a code over 10,000 miles so that can be rules out.
The battery can be tested by any motor factors but please dont be forced into buying a battery to fix this fault.
The 109 relay only effected cars before 2002, when you turn the ignition on do you hear the slosh from the pump in the tank?
I know of no garage which would remove and clean the injectors on one of these cars as a matter of course, more likely they put an addative into the fuel filter/tank.
Unplugging the coolant sensor will cure starting problems in 80% of cars, thats because the glow plugs go on for ages and this increase compression. This normally causes problems with cold starting.

The list of things which I think it could be are:
Lazy starter motor (this would not cause the idle problems though)
Alternator clutch on its wayout (just open bonnet and watch the alternator tensioner to see if the belt jumps when the engine hunts)
i'm leaning towards it being a blocked EGR. If you have the ablitity of reseting fault codes you may wish to try and block the vacuum hose from the top of it and unplug the MAF.
Both will cause warning lights but the car will ignore that sensor.
 

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Discussion Starter · #7 ·
Thanks for the replies. Yes I can hear the pump when I turn the ignition on. The battery has also been tested today and it's ok. I have got it booked in to an independent garage on Thurs so I'll keep you posted with any findings. Thanks again.
 

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Discussion Starter · #8 ·
Hi,

Forgot to update this thread. I got the car back from the garage and they reckon it's the dual mass flywheel that's causing the issue but they are not 100% sure and can't be without a lot of costly investigation work. Cost of replacement including clutch is ?850.
 

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Hi,

I didnt want to start a new thread as I am having a similar issue, if not the same... The car really struggles to start after I have driven it and the car has warmed up e.g. a 20min drive down the M1, get out of the car, nip into a shop, get back, try to start the car and it takes about 6-10 seconds to start and sometimes with a bit of a thud/jump. I dont think its got a rough idle but it does feel like the car wants to start moving from sitting still, but im very new to a diesel engine as I only bought the car 2 weeks ago (its still under the independant garage warranty).

I'm wondering if a replacement dual mass flywheel and clutch solved the issue?

I've read on various forums that it could be the battery, coolant sensor, mapping issue, a broken crank seal, starter motor etc etc

All of the above solutions (which worked for various people) are supposedly linked to a crank speed issue when hot. From another thread and user...

"Apparently, when ECU senses the engine is hot, when starting, it does not start injecting deisel until the starter is turning engine over at 250 rpm or higher.
When hot, the engine compression is higher, so it puts a bigger demand on starter motor and battery, and hence makes it harder to reach 250 rpm threshold."

Im at a loss really about what to do, the garage i bought the car from are looking at the car again for a second time next week after they said they couldnt repeat the issue . There are no fault codes which makes it hard for the garage to determine the fault and the car passed a major service at a main VW dealer the other day. So with no faults it cant be any sensors and as it passed a major service i dont think it can be the timing belt or battery as these are checked... or could it be?

My car is a Golf Mk5 105 TDi Sport (05 reg). Its only done 42k miles. I really like the car and want to keep it for as long as I can, but this issue is annoying and can be embarressing... any help/ideas will be very helpful!! I can then give these to the garage next week

Cheers,

Chris
 

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It can be one of the sensors without an error-code.

Is the car new (to you) from a dealer? If they can't repeat the issue then you should film it or something to show them that it exists.

Once you've proved there's an issue then they need to systematically (normally starting from cheapest up to most expensive) replace the common causes. Don't be fobbed off because they "can't recreate the fault" it's nonsense. If it's been recently purchased then don't accept the car back until it's fixed, or demand a refund - you're entitled to it, legally.
 

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Hi Sando,

It is new to me from a dealer. I'll film the issue tomorrow after taking it for another drive so that I can show them. Thanks for the help!

Cheers,

Chris
 
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