Poor starting and rough idle on an sdi.

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Stevjoe
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Engine size/power: 2.0 SDI (70bhp)

Poor starting and rough idle on an sdi.

Post by Stevjoe »

Hi all. My caddy is giving me gip. Over the last week or so I’ve noticed it’s getting harder to start and when idling it shakes quite bad. I thought maybe fuel filter so cleaned it all out and put a new filter in. It started perfectly, first flick of the key and idled lovely. Started it a few times and all good. A couple of hours later and back to crap starting and shaking on idle. I plugged in one of those OBD2 reader things and shows no codes. No warning lights either. Do you think I should change the fuel filter again in case it was faulty or am I looking at something else. Maybe injector seals? If it’s seals , anyone recommend someone near to Leighton buzzard in Bedfordshire to do them? Thanks
Stevjoe
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Joined: Sat Jun 26, 2021 11:05 am
Engine size/power: 2.0 SDI (70bhp)

Re: Poor starting and rough idle on an sdi.

Post by Stevjoe »

Has anyone done this themselves? I watched a video showing how to do them and how to set the injectors up, didn’t look too bad a job. Where would be the best place to buy the seal kit.?
Scoobysrt
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Re: Poor starting and rough idle on an sdi.

Post by Scoobysrt »

Get a proper scan done with vcds before you start changing everything.
Are the seals wet?
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Stevjoe
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Joined: Sat Jun 26, 2021 11:05 am
Engine size/power: 2.0 SDI (70bhp)

Re: Poor starting and rough idle on an sdi.

Post by Stevjoe »

I haven’t ventured that far yet. Would that be a rocker cover off job to see. I think I may change the fuel filter again as when I changed it it was great for a couple of hours,
DW2207
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Engine size/power: 1.9 TDI (104bhp)

Re: Poor starting and rough idle on an sdi.

Post by DW2207 »

I'm sure when you change the fuel filter, you need to purge the system with vcds or equivalent. Might be wrong though.

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LouisAMS
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Re: Poor starting and rough idle on an sdi.

Post by LouisAMS »

True, system needs bleeding
Last edited by Giddy on Wed Sep 21, 2022 7:28 pm, edited 1 time in total.
Reason: removed unnecessary quote of previous post
BenT
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Joined: Fri Nov 19, 2021 9:26 pm
Engine size/power: 1.6 CR TDI (102bhp)

Re: Poor starting and rough idle on an sdi.

Post by BenT »

Stevjoe wrote: Wed Sep 21, 2022 7:39 am Has anyone done this themselves? I watched a video showing how to do them and how to set the injectors up, didn’t look too bad a job. Where would be the best place to buy the seal kit.?
I've done this before, it's really not a difficult job at all. You'll need some triple square bits, a torque wrench and of course the seals. I used eBay ones and they were fine. Be careful not to twist them when you put them on the injectors or they may not seal properly; I didn't use a tool for this, just did it manually and put a tiny bit of tippex on the o-ring outers before I put them on as a visual indicator.

A few things to bear in mind - the injectors are steel, the head's aluminium. As the injectors are only clamped on one side, they "rock" slightly and gradually eat into their bores in the head over mileage. If the wear's too bad then new seals might not fix it and you'd need a replacement head. My last one had 220 k miles on it and it was fine though.

Also, the injector clamp bolts and rocker arm bolts are single use. I've re-used them before, but they do snap quite easily. Setting the injector lash is also quite straightforward, I did mine without a DTI gauge. I think the relevant intake cam lobe points vertically upwards when the rockers at it's lowest, but do check the internet because there is a good trick for this!

Finally, once you've got the rocker arms and injector clamps out (and disconnected the electrical connector from the solenoid valve), you'll need to twist the injectors from side to side and simultaneously pull them upwards to release them. I hooked a thick cable tie under the solenoid so I could lift the injector while rotating it with a small crowbar. You shouldn't need a slide hammer.

Finally finally, when you re-install the injectors, give them a good hard shove into the bores to seat them correctly. Just tightening the injector clamp bolt to pull the injector down can damage the o-rings, apparently, because it pulls the injector down at an angle.

Hope this helps and good luck!
BenT
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Engine size/power: 1.6 CR TDI (102bhp)

Re: Poor starting and rough idle on an sdi.

Post by BenT »

Sorry, one more thing... On mine, I didn't need VCDS to purge. Just keep turning the ignition on and off until the squelching noise stops. Or, you can apply a vacuum pump to the fuel return line and crank the engine by hand with the ignition on (glow pugs out) to do it... I bought VCDS to purge my 1.6 CR, only to find that it did exactly the same job as turning the ignition on a few times!
Stevjoe
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Re: Poor starting and rough idle on an sdi.

Post by Stevjoe »

Was yours an sdi? Do you know the torque settings for the sdi engine .
BenT
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Engine size/power: 1.6 CR TDI (102bhp)

Re: Poor starting and rough idle on an sdi.

Post by BenT »

Nope, mine was an ASZ PD130, but the top end is, to the best of my knowledge, identical (excepting the injectors themselves). Torque specs from my Haynes manual for the SDI are:

Cam cover bolts: 10 Nm

Injector rocker arm shafts*:
Stage 1: 20 Nm
Stage 2: 90 degrees

Injector clamp bolt*:
Stage 1: 12 NM
Stage 2: 270 degrees

*Use new bolts
Stevjoe
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Posts: 20
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Engine size/power: 2.0 SDI (70bhp)

Re: Poor starting and rough idle on an sdi.

Post by Stevjoe »

I noticed today that if I leave the ignition on for a few minutes it starts fine. Am I right in thinking that when the engine is off the fuel system loses pressure due to the seals leaking. Leaving the ignition on for a few minutes rather than 20/30 seconds restores the fuel pressure.
BenT
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Posts: 68
Joined: Fri Nov 19, 2021 9:26 pm
Engine size/power: 1.6 CR TDI (102bhp)

Re: Poor starting and rough idle on an sdi.

Post by BenT »

Interesting... I always thought with mine that the electric lift pump only ran for a few seconds and then switched off. But maybe not.

Have you checked your engine oil level lately? If the injector seals are leaking then the fuel's going somewhere - either dripping down into the cylinders or leaking out of the top of the injector bores. If the latter's happening then your oil level might rise if you do mainly shorter journeys.
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