D24TIC Making very little power

[Kaptin]

Hi all,

My D24TIC is making very little power. Timed a 0-60 and it's 19 seconds, it's a bit brutal (it's in a 940). It's making 12 PSI boost, so it doesn't appear to be a boost issue. It also loses legs very quickly - acceleration is best between 2500-3000, it slowly accelerates at higher RPMs.

Does anyone have any ideas as to what it may be? I'm doing the timing belt and injector pump belt + timing tomorrow.

Scratching my head a bit though, as it seems to run nicely, so I wouldn't have thought the timing would be too far out!

Many thanks for any ideas you may have!

[v8volvo]

Definitely sounds too slow. These engines are quite speedy for an old-tech diesel if everything is in proper condition and tune. Especially the higher output intercooled edition like yours. Power should start to come on strong by around 2000 rpm and stay strong up past 4000 before it starts to taper off.

When was most recent fuel filter change? And air filter?

Any signs of excess smoke when it starts to lose power? And does the power recover quickly when you get back down to low RPM after it loses steam at high RPM? Or does it seem breathless for another few seconds, want to idle extra slow until it bounces back, etc?

Is this an issue that has always been present with this car (how long have you had it?) or did it develop more recently after the car had previously been running stronger? If the latter, did it occur suddenly or gradually get worse over time?

Loss of power at higher engine speeds is textbook classic fuel starvation. It could be textbook airflow restriction too (from clogged air filter or exhaust) but normally that would be combined with big clouds of of black smoke which you didn't describe seeing. So fuel would be the first guess.

There are a few other possibilities too:
- mis-adjusted injection pump fueling rates
- fuel system restriction upstream of the fuel filter (at tank pickup for example)
- leaking or disconnected boost enrichment signal hose from intake manifold to top of inj pump
- problems with EGR system (if equipped) causing either EGR leakage under heavy load, or restricted intake manifold from EGR oil/carbon buildup
- incorrect injection or cam timing, possibly involved with a stuck cold start device or improperly connected high altitude compensation system
- some others

But these are all less likely than a simple plugged fuel filter, so pursue that first. Even if the filter is fairly recent (or believed to be), worth changing it again, as they're cheap, and even one tank of contaminated fuel can plug a filter. If confirming no fuel supply restriction doesn't get it more lively, then there are next steps to check from there.

One other recommendation though -- experience (mine and others'!) shows that, if possible, it would be good to wait on the cam belt and injection pump work until AFTER you first finish diagnosing and solving the low power issue. Introducing more variables always makes troubleshooting harder, and if you do the belt/timing work, then you will be changing multiple factors at once, and it could become hard to know what cause is leading to what effect. E.g. -- not saying this would happen, but it could -- if cam or IP timing ended up not being right on the mark after the belt work, then that might mean there are TWO independent factors causing the engine to run incorrectly, and making organized diagnostic progress in that situation could become very challenging.

Usually much more effective to change one variable at a time in pursuit of one targeted problem, then move on to the next problem once that first one is solved. The one scenario in which you might want to disregard this advice is if you are concerned that the timing belts might be so aged that they are at risk of snapping anytime -- in that case, yes, best to change them ASAP (using correct tools/procedures) and worry about the power concern later.

[Kaptin]

Thanks a load for that extremely detailed answer V8Volvo. I actually bought it very very recently, I found the forum posts for the previous owner from the forum, you had tried to help him with this issue too! Though not quite as I have described it, as I've done more checking.

Boost enrichment pin is what I T'd to to detect boost, so the boost is definitely getting to there (could be an issue with the boost portion of the IP I assume though!)

Fuel system stuff is a good call, I never considered that - I have a new filter to go on, so can do that too.

It is EGR'd but will be being blanked today too

IP troubles like the cold start device worry me more, as I have no idea how to check them - I've been looking into modding the IP, and it's rather complex to say the least!

Thanks for the suggestions - one thing I meant to mention was that it's extremely clean smoke wise, so I did suspect that fuel may be related. There's essentially never a puff, which I know is odd for these - my father has one, nice and smokey. You mention the injection quantity, I'll definitely be checking that out, though I don't want to just turn it up and mask a separate issue.

I'd love to wait, but from the forum posts of the previous owner it was very overdue a timing belt a year ago! Which has not been done - so it at the very least needs done, but as you mentioned not ideal as changing multiple variables. Needs must in this case unfortunately! What I may instead do is just the timing belt, then IP belt - separately, if possible. Thanks - will let you know of any progress

[ngoma]

Originally Posted by Kaptin

There's essentially never a puff, which I know is odd for these - my father has one, nice and smokey.

In my experience, in proper tune, these are not big smoke emitters, especially for their era, especially compared to Mercedes, Pugeot, etc.

Echoing v8volvo here, change the FF first, then look at LDA settings and inner workings. Good that it is seeing good turbo pressure, but that might not be getting converted into sufficient fuel pin movement or fuel collar movement.

[Kaptin]

Many thanks to both of you.

Having changed plenty of pieces, it seems that it was all down to the fuel/LDA pin. It still had the collar welded on very well, with tamper paint etc - so definitely had never been touched. Instantly resolved the power issue. I am at a loss as to whether it was misconfigured for the last 275k, or perhaps had a misconfigured renovated pump, but it is sorted at least! Thanks for all of the help and suggestions.

[ngoma]

Glad you were able to solve the problem, but you have confused me. What do you mean by "fuel/LDA pin?"