Caddy 2.0l SDI (BST engine) starting issues

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Hi all, firstly, thanks for your time to read this.

I bought a 2009 Caddy with 2.0l SDI.

The engine was running rough and was misfiring on cylinder 3, 2 was not much better. It tended only to misfire when hot and was running ok when cold. However I had starting issues the whole time... eventually she would go, but took a lot of turning over and a bit of gas.

A garage then changed the wiring loom and replaced all the glow plugs and the misfire was a little better... and tended to start better intermittently, but not perfectly.

I did a lot of research and decided to change all the injector seals and replace a very black fuel filter.

After eventually starting the engine on tow as had issues getting fuel back to the engine, the misfire has improved massively, pretty much gone... however, I am having more issues with the starting.

I’m suspecting either 2 things, perhaps I got a duff bunch of glow plugs from the garage and it’s not hot enough, or there is a relay problem?

-What resitance should be measured across the glow plug terminals?

I’ve also just read on another post which suggested testing the starter motor the dirty way by removing the engine temperature sensor as it may be an issue with the starter motor not cranking over quickly enough.

-Where is this sensor located as I would like to test this?

Any advice and ideas will be a huge help, thank you all in advance.
 

Crasher

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I immediately go back to the fuel filter, if the fuel in there is black it means it is contaminated with engine oil from a leaking tandem pump which significantly reduces the Cetane of the fuel so the pump needs replacing and the system flushing out, a Diesel fuel cleaning additive would be a good idea to get the injectors clean. The coolant sensor is in the plastic water housing on the end of the head over the gearbox BUT do not try this without a proper VAG specific code read first as starting it with the sensor disconnected will store a fault code which will complicate a fault code read result later.
 

Refuelled

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I immediately go back to the fuel filter, if the fuel in there is black it means it is contaminated with engine oil from a leaking tandem pump which significantly reduces the Cetane of the fuel so the pump needs replacing and the system flushing out, a Diesel fuel cleaning additive would be a good idea to get the injectors clean. The coolant sensor is in the plastic water housing on the end of the head over the gearbox BUT do not try this without a proper VAG specific code read first as starting it with the sensor disconnected will store a fault code which will complicate a fault code read result later.
Hi Crasher, thanks for the reply...

Sorry, I mean the filter was black, NOT the fuel in there. Haven’t a clue when it was last changed.

Would you still suggest changing the tandem pump? Definitely agree regarding the additive.

Thanks again.
 

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Unless the fuel was obviously black with oil the no. Your first step needs to be a code read.
Ok great. Yes had it read today and only issue was misfire cylinder 3 yet it doesn’t sound bad at all. That’s why I am a bit stumped on the whole thing really! Just trying to work out what the next thing to try is really... I think I read a previous post by yourself and came across the whole starter motor suggestion which sounds very similar to mine.
 

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You need to study the injector balances in live data
Lovely I’ll get that arranged this week.

are you able to tell me if this model has an electric fuel pump and non return valve in the fuel supply line from tank to filter or does it rely solely on the tandem sucking the fuel all the way from the tank?

thank you
 

Crasher

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Yes these have an electric lift pump in the tank, if engine oil gets into the fuel from a leaking tandem pump, they clog up and fail.
 

Refuelled

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Hi again Crasher... so got a code read and live data and all seems ok.

I’ve replaced the tandem seals with a new kit and also fitted a non return valve before the tandem pump.

Still having the same issues. I’m now thinking it is the lift pump which is the problem. I was wondering if you could tell me if there’s supposed to be a non return valve in the fuel filter housing or anywhere along the system at all?

It seems to start better on a full tank also which points to fuel supply issues?
 
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