Fast idling when cold?

[Lotustuart]

I have just serviced my 97 2.5td auto. Oil, oil filter, fuel filter. And now I have a problem with fast idling upon cold start. Normally it revs to about 1100 revs for a few minutes til warm and the fast idle solenoid switches off and it sits at 700. Now, the FIS pushes too much and she revs at about 2500-3000 revs til warm. I have adjusted the screw and now she idles at 1500 til warm but she seems a little off. The only thing that's different since the service is the new fuel filter is slightly longer(top to bottom) than the original. I can't see how this would affect the idle but I'm no mechanic. Any suggestions?

[Northern Bongolow]

do a search (top right) and type in cold and start and solenoids.

[Lotustuart]

Tried that. Nothing helps. It's very strange.

[Northern Bongolow]

several things control the revs.
http://www.demonav.ru/For_work/104740-0824.jpg.

the diaphragm (top left of the link) via the cold start solenoids and the throttle position sensor and the throttle cable adjustment.
the revs should remain under 850-900 revs on tick over,AT ALL TIMES or the glow plugs get switched off via the ecu. even when the 2 cold start solenoids are operating, all they do is maintain the 850-900.

sounds like a throttle position sensor fault to me. but it is a strange one.
any chance of putting a vid up on youtube.

[DemonAV]

Idle (on the warm car) should be 700 - 780 r / min, adjustable nut on the switch XX.
A diaphragm increase idle speed up to 800 +/-25 under load (air conditioner, power steering, lights ...)
B diaphragm increase idle speed up to 1350 +/-150 at warming.
They are controlled by vacuum 53KPa.
On cold car and turn the ignition ON and rod should be drawn into the aperture. If vacuum is not present, and the diaphragm are not working. But that's another story.
A screw regulates the warming setting (NOTE : only when vacuum system is OK!),
B screw regulates the load setting (NOTE : only when vacuum system is OK!).
See it all in the picture:
ru/download/file

[Lotustuart]

Idle (on the warm car) should be 700 - 780 r / min, adjustable nut on the switch XX.
A diaphragm increase idle speed up to 800 +/-25 under load (air conditioner, power steering, lights ...)
B diaphragm increase idle speed up to 1350 +/-150 at warming.
They are controlled by vacuum 53KPa.
On cold car and turn the ignition ON and rod should be drawn into the aperture. If vacuum is not present, and the diaphragm are not working. But that's another story.
A screw regulates the warming setting (NOTE : only when vacuum system is OK!),
B screw regulates the load setting (NOTE : only when vacuum system is OK!).
See it all in the picture:
ru/download/file

Thanks.
It's the A screw that is over working. It seems to want to push too far, ie. over rev it. I have wound it back but it's still not right?? I won't get time to video and YouTube it till at least Friday.
Any more clues? Thanks.

[Northern Bongolow]

screw A is controlled via the cold start solenoids, via the large diaphragm A/ B. remove the pipe to the A end, then the B end, the revs should drop to normal once the offending solenoid is removed.

[Lotustuart]

screw A is controlled via the cold start solenoids, via the large diaphragm A/ B. remove the pipe to the A end, then the B end, the revs should drop to normal once the offending solenoid is removed.

So is something in need of replacing? Just removing the pipe won't "fix" the problem, surely???

[Lotustuart]

screw A is controlled via the cold start solenoids, via the large diaphragm A/ B. remove the pipe to the A end, then the B end, the revs should drop to normal once the offending solenoid is removed.

So is something in need of replacing? Just removing the pipe won't "fix" the problem, surely???

[Lotustuart]

screw A is controlled via the cold start solenoids, via the large diaphragm A/ B. remove the pipe to the A end, then the B end, the revs should drop to normal once the offending solenoid is removed.

So is something in need of replacing? Just removing the pipe won't "fix" the problem, surely???

[The Great Pretender]

The only thing that's different since the service is the new fuel filter is slightly longer(top to bottom) than the original. I can't see how this would affect the idle but I'm no mechanic. Any suggestions?

I agree with your logic, if nothing else has been disturbed and nothing else has gone t!ts up the bigger filter could be the culprit..
Refitting the original would maybe show a way forward?

[Northern Bongolow]

screw A is controlled via the cold start solenoids, via the large diaphragm A/ B. remove the pipe to the A end, then the B end, the revs should drop to normal once the offending solenoid is removed.

So is something in need of replacing? Just removing the pipe won't "fix" the problem, surely???

no but it may help to diagnose which bit/s are faulty.
did you remove each pipe in turn, if so what was the outcome.

[Lotustuart]

Thank you for all your advice. I seem to have found the issue. Whilst looking at it and thinking about what you said, I wriggled a pipe and the whole unit (both solenoids) moved. Screw A is pushing the unit back causing higher revs than it should. It would appear that either a bolt has worked loose and fallen out or was never there (since I've had it)and I knocked the unit when I changed the fuel filter. It's the top bolt with Allan key head (centre of the picture above the rubber gator.). I have tightened the bottom bolt to hold the unit firm till I can source a new bolt.
Fingers crossed, problem solved for the cost of a bolt!
Thanks again for the help. Much appreciated.
Stuart

[The Great Pretender]

Result

[Northern Bongolow]

i love a cheap fix meeeeeeeee.