Smooth ride success.. but problem with bosch turbo pump

[maxgreenwood]

Well I'm pleased to report that after a few more hundred miles on hydraflush, the ride on my bx has become alot smoother. A combination of filtering the Hydraflush after 400 miles, greasing up the HCs and greasing the externals of the struts seems to have worked wonders. I have still to get round to internal flushing of struts, but they're nice and smooth now. I smile when i get out the car now and the height corrector adjusts the suspension back down. Citroens eh! They sometimes stick a little after parking on our sloping drive, so i'll try the internal flush, see what that does.

I also have recently replaced the fuel lines.. mmm the taste of diesel!

My next job to tackle is the fuel pump / turbo. I have a slight boost from 2000rpm upwards, but its nothing like it should be, feels about the same as my old ZX 1.9D N/A. Although the car is running fine, i would like to solve this mystery. I can hear the turbo whistling, although actually only when engine is cold. I took it to a diesel fuel injection specialist here and they had a quick look under the bonnet and said it could be a seized piston, or perhaps more unlikely a perforated diaphragm in the pump. They're gonna charge (a not too hefty sum) to look at it anyway.. and then..

My queston is.. Is there a diagnostic process i can go through myself to determine the problem?

And does anyone have a turbo bosch pump lying around they could sell me in case i need to replace it?

[jonathan_dyane]

The most common cause of this fault is simple and cheap to fix.

There is a hose which connects between the intercooler and a widget on the pump, and this is responsible for informing the pump of the level of demand for extra 'on boost' fuelling. The pipe is the same diameter as a petrol hose and runs from the centre front of the intercooler to the pump.

The pipe eventually goes porous and soft, and begins to leak, with the result that the engine is no longer given the fueling it needs to make use of the boost from the turbo.

Replace this first!

[maxgreenwood]

Thanks Jonathon,

I tried it today - replaced the hose and no change. I revved the engine to check air coming from turbo down that pipe and there is some air blowing out but i think it should be quite high pressure? I tried driving with the hose disconnected so no turbo and to be honest the difference with and without it is negligable!

The car did feel slightly more sprightly last year with a bit more boost i think. Could the air manifold from the turbo be leaking somewhere? Where do i trace it from? theres not much room in that engine bay.

the ride is continuing to improve, about 850 miles on Hyrdaflush at the mo, lots of citaerobics and struts are smooth. steering is nice. at least that is making me happy!

It just won't go up hills!

Where do you think i should look next?

[Geoffrey Gould]

Hello would you remind me/us the make of the turbo please, it may be that the wastegate has stuck, the best way to find out is to put a booste gauge into the small pipe with a 'tee' piece (from the intercooler to pump.)refered to in the post above. Maximum booste is about .9 bar (approx 13 psi). Drive it up a hill, plenty of throttle make it work hard and see what happens. Just revving the engine standing still will not work too well.
Cheers.
Geoff.

[Jaba]

The wastegate usually sticks in the closed position. It is easy enough to check from underneath the car.

The turbo shaft could be seized/stuck as well. This is more difficult to check as it involves removing the air outlet hose and, with the engine off seeing if the compressor impeller spins freely. You have to swing the engine forward to do this easily.

[jeremy]

Just a silly thing before this gets too complicated. Is the accelerator pedal still attached and opening the throttle fully?

RHD BX suffer from the accelerator bracket splitting from the pedal box.

On the test drive of mine I couldn't get it over 30 MPH. It was cheap and had water and oil in it, started reasonably well and didn't make any strange noises - so I took a chance knowing that I might get a bill.

I duly picked it up and at 30 MPH filled it with fuel. I was then driving it in 2nd gear between cars parked tightly on both sides when I kicked the pedal to the left and suddenly it took off with clouds of dirty smoke from the back.

I made up a re-inforcing bracket from some 1 inch angle which I was able to fit without drilling the car and its still there 9 years later.

Signs are a floppy pedal - check that the lever on the pump is fully open AS THE PEDAL HITS THE FLOOR. Don't adjust too tight or the nylon clips on the throttle end of the cable will fall off and/or you'll damage the pump linkage.

[Way2go]

I duly picked it up and at 30 MPH filled it with fuel.

That's a rare talent Jeremy, "in-motion" re-fuelling.

[ken newbold]

Sounds to me like pedal box fatigue.

Could be an air leak, intercooler or pipework but not that common, however pedal box probs are very common.

Check for sideways movement in the pedal.

[maxgreenwood]

the pedal is slightly wobbly 2-3 mm sideways movement but it does make the throttle on the pump travel all the way ie. hits the (max fuel screw?).

There is air coming down when turbo feed disconnected, i guess the only way to find out if thats doing its job properly is to do the pressure test.

I'm not sure what turbo i have or where to look to see if the wastegate is not open properly.

I have this intermittent problem with fueling sometimes below 2000rpm with the car lurching back and forth - in all gears, and it disappears above 2000rpm when i can feel some boost. It feels like an air/fuel mixture imbalance. Robin (Citroen7) over here reckoned it was something to do with fueling. It doesn't happen all the time but my boost problem does.

I wonder if the two may be related. Hoping anyway! that i'm not looking at 2 seperate problems

I think i'm going to take it in to be looked at.

[jeremy]

There is no air - fuel mixture - the thing runs as fast as it can for the amount of fuel injected.

The limit of power available is basically reached when there is no more air available - when the turbo pumps in more - which requires more fuel which is provided by the extra fuel device on the side of the pump. This is sensitive to boost pressure and is connected to the intercooler by a thin pipe.

[maxgreenwood]

ok sorry excuse my limited knowledge of cars. If you havn't gathered already, I'm new to this game but getting to know mine. The forum is an invaluable resource.

maybe an injector is duff? although engine revs fine and all the way to around 4,500 / 5000 rpm. or maybe the air system has a leak.

the intercooler pipe i replaced and is all connected well.

the diesel injection specialists here, they seem trustworthy and have loads of experience reckoned it might be a seized piston in the over-fuelling device or a puncture in the diaphragm of this.

They were "oh - a proper car!" after i told him what i'd got... referring more to the fact its a totally mechanical system as opposed to modern ECU governed ones.

i'm going to take it in to them i think. they can thoroughly check it over for about €50 they said.

[jeremy]

I think if it were one injector you'd get clouds of smoke - as it would produce poorly atomised fuel - ie droplets too large to burn in time.

Could be the extra fuel device full of crud or damaged. I'd let your guy have a look at it.

Could be a fuel supply problem - ie air getting in or restriction like a dirty filter not allowing enough fuel to pass. Most air problems show up as bad starting.

[maxgreenwood]

Wow! I mean.. what a difference!
'Diesel Fuel Injection' in Dublin sorted the car for me today and pretty cheaply and quickly too. It was a punctured / split diaphragm in the overfuelling sensor... a Lucas pump. They replaced it.
I'm now scared of this car! Its a different beast altogether. Low rev response is very good now too. it drives itself. And when the turbo kicks in.. it takes off. Big smile on my face.

Can't believe i've been driving it for all this time as it was, and so happy its sorted!

Now i need those new back brake pads and discs on and that should help stopping the thing.