Lumpy

[snarkosnarko]

Hi
I
have an 850r auto which was running fine apart from turbo return pipe seal leaking, just haven't got round to it.
Started to feel lumpy on motorway journey so pulled over.
Felt like it was only running on 2 or 3 cylinders.
Checked obvious leads etc, and got towed home. No sign of head gasket failure, all coolant/ oil ok.
Have replaced leads, plugs, rotor arm, dizzy cap, coil, injectors, and ecu from another 850r just to prove parts. All ok.
Temperature fine, codes are 1-1-5 and 1-5-5 injector faults cylinder 1 and 5. Wiring loom cheked ok, injectors already replaced.
I am at a loss as what to check next. Return pipe now fixed.
Any ideas?
Martyn

[Alan M]

Have you cleared the codes? Clear them if you haven't. Have you checked fuel rail pressure at the schrader valve? Use some conducting medium in the connectors to the injectors also. Vasaline will do the job.

[snarkosnarko]

I've not been able to clear codes, i presumed because fault was still there.
Have obd port so i'm using the multimeter method, wires in 3 and 16 then short 3 and 5 for codes and short for 15 secs to clear.
How do i check fuel rail pressure, do i just connect tyre valve?
Cheers

[Alan M]

Yes a gauge on the schrader valve when running to look at the pressure reading. Check on the VOC for the clearing sequence for the codes as I think you are doing it wrong. When I get to my pc at home I will check what the link is. If rail pressure is not what it should be (3.06bar around 44psi at 0 manifold pressure and lower at idle under vacuum) it may be worth checking to see if the fuel regulator is operating correctly. The vac port on it should hold a vacuum when applied to it if not it may be perforated and need changing. Also check to see what the impedance values of the injectors are. The values can be checked with a multimeter and be balanced across all of them at around 14 ohms depending on injector model.

[snarkosnarko]

Many thanks
I'll get on to this tomorrow. I've checked forum and my method for clearing is wrong, i'll try short 3 and 5 for 5 seconds remove and re short for three.
Let you know how i get on.

[snarkosnarko]

Have now cleared codes successfully, now 1-1-1 however same fault.
Injectors are orange and resistance is equal 16 ohms all across.
Help!!!

[snarkosnarko]

Just to update
Been out and bought a compression tester.
11 bar cylinders 245 no compression at all cylinders 1 and 3.
Does this indicate sticking or burnt valves?
Was giving it a "good run" prior to problem.
Is there an easy fix or is it head off.
Any idea of costs DIY
Cheers

[Alan M]

If you have no compression on two cylinders it sounds like its a head off at the minimum to check the head and cylinders for any obvious problems.

[snarkosnarko]

Hi
Took the head off yesterday and found as suspected burnt exhaust valves cylinder 1 and 3.
Any idea of costs to rebuild head, or does any body have one kicking around?

[brett craig]

whats happened to the broken parts of the valves ? have you checked piston/rings bores for damage ?

[snarkosnarko]

Piston rings and bores look fine.
There is no sign of broken bits, now you have got me thinking they may have been blown out and caused some damage to the turbo?

[brett craig]

with anything that fails it always leaves a trail somewhere, and there not small bits !

i would certainly investigate further, if the bores are unscored then track back from the exhaust valves all the way to the exit of the turbo, no point spending a fortune rebuilding to only find theres more hidden damage.

[snarkosnarko]

Have stripped turbo, no visible damage.
Bits must have disintegrated as no sign.
Having head checked over today, new parts on order.

[t5 pete]

sames happend to myne and just had the turbo off and no damage there also

[snarkosnarko]

Head now back from machine shop. Actually needed 4 valves, 2 had hairline cracks, new stem seals and re-lap, 5 thou off face.
I'll try and put it all back together tomorrow.

[GregE102]

Head now back from machine shop. Actually needed 4 valves, 2 had hairline cracks, new stem seals and re-lap, 5 thou off face.
I'll try and put it all back together tomorrow.

Very Sexy Picture!

[fireclown]

the valves have been burnt away, i would of thought they would of been vapour when they exited. good luck with the build. should drive like a new car when its done.

[t5 pete]

What fuel were you using as i have heard of a few t5's having this problem all around the same time and all having the same symptoms and same missing bits of valves.
I know the bit of the valve that broke off myne looked like it had been cut with the oxy acetylene.
Can anyone think of a reason why this is happening.

[snarkosnarko]

Guy in the machine shop thought bad fuel.
Not owned it that long so damage probably already done, although i was driving it very hard prior to failure.

[fireclown]

Try using a fuel additive every now and again. its when deposits get left on valve seats and are allowed to build up this happens. forte do a very good one. this will help with the crap supermarkets fuels about.