Diesel whiz needed! Narrow power band and smoke!

arry_b · Post by **arry_b** » 29 Oct 2004, 04:43

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ghostrider

yeah but only til the headgasket blew ! [:D] [:D] [:D] [:D] [:D]
<hr height="1" noshade id="quote"></blockquote id="quote">
Only the head gasket - you weren't trying hard enough. I had a head split right open like a Donner Kebab on an Imp Sport I had.
And these Citroen chaps think *they've* got gasket problems[:D][:D][:D]

oilyspanner · Post by **oilyspanner** » 29 Oct 2004, 05:08

I was an imp victim too, the only reason they called it an IMP was that the bootlid wasnt wide enough to call is a Bas*****, but it taught me a thing or two about cylinder heads.
Stewart

NiSk · Post by **NiSk** » 29 Oct 2004, 13:12

A couple of carefully positioned extra holes in the rear crossmember of the Imp allowed engine removal in less than 30 minutes. There was a solution to head gasket problems as well - Wells rings. My Carter-tuned rallye Imp was putting out about 120 hp at 9,800 rpm - boy did it fly! (as long as the transmission held - I went through the entire system, beefing up all the components as they failed! rotoflex joints - drive shafts, clutch assembly and finally the complete transaxle!) Far too much grip, despite the low weight.
Carter even fitted a Triumph Spitfire crank to an Imp engine, after machining the crankcase and reinforcing it, he got nearly 1300 cc - still it was a cheaper solution than the Twin-Camifornian that was running the tracks - talk about head gasket problems!
//NiSk

Kowalski · Post by **Kowalski** » 29 Oct 2004, 15:15

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Robin

Under these conditions flooring the pedal will actually hinder the acceleration by causing overfuelling. Backing off can often give you an increase in speed. <hr height="1" noshade id="quote"></blockquote id="quote">
A properly set up diesel will have no problems with overfueling, they have a boost compensation device on the fuel pump so that they don't overfuel.
If your Xantia overfuels at any point in the rev range you need to get it adjusted so that it doesnt. Overfueling a diesel just wastes fuel, if you were really interested in cutting edge performance you would have a petrol.

AndersDK · Post by **AndersDK** » 29 Oct 2004, 23:23

Interesting Imp discussion [:)]
Me too - i use to get carried away on oldtimer discussions - but just for once - should we try keep on track with this DERV problem [:D]
This Xantia seems to have way too late turbo response - I.e. it should in fact kick in around 2200 with noticeable boost.
Other than previous mentioned problem areas with air filter & coked exhaust, I believe it could be a problem with leaking inlet air - or a leaking bypass valve (wastegate) - may be partly stuck open.
I dont think injectors are an issue - as they would never "drool" that much during engine running, unless a gross failure like a stuck open injector.
Could simply be a slightly worn roto-pump in need of service or re-adjusting.
A fast solution is visiting a diesel (not Citroen) specialist garage. They would quickly find the problem with such clear symptoms.
Turbo's on modern engines are quite long lasting - would normally outlast car/engine. A common turbo problem is a failing oil seal/bearing on hot side, which immediately gives loads of white smoke from exhaust - constantly.

heath robinson · Post by **heath robinson** » 31 Oct 2004, 22:55

Appreciate your thoughts
I hope I’m not expecting too much, certainly not petrol performance. It is just that with the exception of the 3k slight lift, my td is slower and much more reluctant to go through the post 3k revs than my old non turbo 214k zx and 10mpg less economical; I guess that is the benchmark I’m using.
Looking through your comments, I will double check the air inlet for breaks at the weekend.
As for over fuelling, I’m guessing this is what is happening due to the black cloud behind when really pushed. Are any of the adjustments suggested DIY?
No recollection of white smoke to suggest seals on turbo gone. The asthmatic nature feels like I might guess a half working turbo would. I have no experience of td for comparison. I will have a look from underneath on drive up ramps and see if turbo/waste gate exploration appears DIY. I suppose it makes sense to rule out the jobs I can do before paying a fortune at a diesel specialist.
Thanks again for so much help.
regards

horrid1 · Post by **horrid1** » 01 Nov 2004, 14:17

I suggest you check that you don't have a partial blockage in your fuel line between the tank and your injector pump.I had this problem in a japper bus which sucked lube oil down the valve guides when trying to thrash it, caused quite a bit of smoke!!

NiSk · Post by **NiSk** » 01 Nov 2004, 15:29

Turbo diesels very rarely suffer from valve seal problems - since they operate att positive pressure most of the time, there's no suction down the valve guides.
//NiSk

heath robinson · Post by **heath robinson** » 27 Nov 2004, 15:14

Fuel delivery is now I believe the favourite
This forum is superb for getting the grey matter applied to the problem. Having read through the contributions (thanks again) and driven and experimented with these in mind, a number of things have happened. I’m not certain, but it seems that lots of thrashing through 2nd and 3rd may have improved the operation of the turbo. Either that, or I am now more attuned to its operation.
Whichever, I am now moving away from the turbo as the cause of smoke and poor upper rev performance. Fuel delivery is now I believe the favourite; injectors, pump, timing. If driven sedately and then pushed the car leaves a cloud of smoke. Having driven steadily, if then really pushed, e.g. when setting off on a motorway, during the first push through 2nd or 3rd the there is I think a very faint and minor misfire. This is not evident on the second push; possibly cleaned out the operation of an injector? I also feel the car on tick over, even when hot, smells too much. If it were petrol I would say it was running too rich. Does this tell us anything about injectors/timing/pump?
Look forward to your thoughts
regards

jeremy · Post by **jeremy** » 27 Nov 2004, 15:24

Firstly If I'm going over old ground again - let me apologise - this thread is long and AOL very slow at the moment!
If the exhaust smells with a hot engine its probably your injectors or possibly timing. Diesels have an unimpeded air intake and run in excess air. Under certain conditions there may not be enough air but at idle there certainly is. The excessive smell is unburnt or poorly burnt fuel and this is probably caused by poor atomisation - ie bigger droplets are being injected than should be. You may be able to clear this with a cleaner but probably need to have the injectors cleaned or replace them. You may be surprised at the cost from an independant diesel specialist! - My BX TD ones were done about 4 years ago for £100 and the difference was amazing - including instant starting, discernable fast idle and wider power band!
Jeremy