Smokey 940

[Tom940]

Hi everyone,

This is my first post on here, I own a 1995 940 D24TIC. What a car, I love it. Currently at 182,000. It's been pretty smokey since I got it, its possible that a previous owner has messed with the smoke screw on the pump.

I get a decent cloud at start up when cold which I think is pretty normal for these engines but also leaving big clouds when pulling away from junctions etc. When on boost there's barely any smoke but off boost and accelerating it can be quite embarrassing. This did actually get worse when the fuel filter was changed. Is it possible that now I've got a clean fuel filter the engine is over fuelling until the boost kicks in? I'm hoping it's just a case of backing the smoke screw out a turn or so but with this being my first D24 I'm hesitant to start messing with the pump. Any suggestions or help would be greatly appreciated.

[ngoma]

Welcome to the forum.

Can't think of how a new fuel filter could cause overfueling.

What color is the smoke? Momentary white cloud is common on cold startup. Otherwise a well-tuned engine in decent condition shouldn't ever excessively smoke more than a light haze, certainly not clouds of black smoke. Except during a hard pull after it has been run lightlly for a long time. That is burning off the carbon deposits.

Are you able to contact the previous owner to see what they did? For adjusting the smoke screw, I like to make adjustments no greater than 1/4 turn at a time. TIP: Keep a log (notebook?) of each change amount and results, so you can easily return to benchmark if it worsens after a change. Then smaller increments for fine tuning, maybe 1/8 - 1/16 turn.

Turning it too far can result in no start/stalling/no idle/high idle/runaway condition.

They also may have adjusted the (turbo boost) fuel enrichments settings on the IP "flying saucer" section.

[Tom940]

Thanks,

Not sure about that either just seemed strange to have more smoke after putting a fresh filter on. The smoke was grey off boost whilst accelerating. Grey/ white on start up. Lots of it as well.

I had a go at adjusting the pump yesterday. I turned the smoke screw on the top of the pump one full turn anti clockwise in small increments, if I'm right this controls off boost fueling. Seems quite a lot better now. Small cloud at start up which soon clears and on my 20 mile drive to work this morning not a single bit of smoke pulling away after idling. Hopefully this has done the trick.

[ngoma]

Originally Posted by Tom940

I turned the smoke screw on the top of the pump one full turn anti clockwise in small increments, if I'm right this controls off boost fueling.

Depends which "screw on the top of the pump" you are referring to. #10 in this photo is the one commonly referred to as the smoke screw, or max fuel screw. The screw at the very top is the one that adjusts changes in fueling according to turbo boost pressure.



(courtesy of https://www.306oc.co.uk/forum/showth...=131&pid=90467)

[jpliddy]

hi Tom
ive had my car 23 years now im based in north staffordshire i can do all basic servicing my self but im not too techno .there a few lads with this engine scatter about the country who i can point you to for information if we exchanged details
im a retired carpenter ,please let me know
regards jim

[Tom940]

Hi Jim,

Thanks for the reply I'll send you a message.

Tom

[jpliddy]

hi Tom i can send you my mobile number in email if thats best way to have a chat about our 940 diesels ,im on whats app too if that helps

[jpliddy]

Originally Posted by Tom940

Hi Jim,

Thanks for the reply I'll send you a message.

Tom

hi tom i have sent you my contact details can you see them yet ?
regards jim

[Tom940]

Hi Jim,
I've sent you a message, haven't logged in for a few days