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Darkslider

1.6 Tdci Focus Down On Power, Boost Pressure Questions!

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Hi everyone, new member here just signed up as my 2006 1.6 TDCI Focus has developed a problem. Have had a read through the common problems thread but can't find anything similar so thought I'd ask for help.

The car's really down on power and quite flat, struggles on hills though just about bearable on a flat road but suffering a severe lack of power. I initially thought the culprit was the MAF as it drove exactly the same whether the MAF was connected or not. I bought a copy of ELM 327 the diagnostic program and interface and plugged into the car, and it's got no fault codes registered. Decided to have a look at the live data.

The Air Flow and Temperature readings seem about right, the air flow is 0 with the engine off, around 8 to 10 kg/h at idle and rises when the engine revs as you'd expect so that seems to be working correctly.

However the manifold pressure is a bit odd, it will not budge from around 14 psi no matter what you do. With the engine off it's reading between 13.9 to 14.6 psi, but with the engine running and revved at idle this value doesn't change at all.

The engine starts and runs fine, it's smooth enough on all four cylinders (had two brand new injectors fitted around a month ago) but it does drive as if the turbo is doing absolutely nothing and it can't be heard to boost either, so I suspect that is my problem.

My question is what could be causing the lack of boost pressure? Or is it likely to be a duff MAP sensor? Do these have a boost solenoid that actuates the wastegate? If that's failed might it be keeping the wastegate permanently open and not allowing the turbo to build up any boost?

I'm fairly handy with the spanners but the electronic diagnostics side of things is a bit of a new one to me but I'm slowly learning and teaching myself as I go along. Any advice would be appreciated, I suppose my next step is to check and clean out all the manifold pressure/boost solenoid pipework in case the dreaded oil build up has blocked any of it, but I'd appreciate any advice on testing the individual sensors in question as well and where to look next.

Thanks!
Brendan

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Is the car smoking at all? I would be checking all the intercooler pipes for splits first off as if you are losing boost then power would be down. Do you have the engine systems fault message and MIL light on or not?

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Nope, no smoke, rattles or nasty noises, engine revs up fine just flat with not much power. No MIL light or fault codes logged at all.

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One thing I would be interested to know is as the MAP sensor is obviously capable of reading vacuum as well as pressure, does my reading of around 14 psi equate to a constant 14 psi of boost? This seems unlikely so I'm assuming the reading of 14 psi is actually atmospheric pressure, which would suggest a split or loose turbo hose somewhere if it wasn't for the fact that the turbo doesn't seem to be boosting at all and no air loss can be heard anywhere,

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I could be wrong but I think there should be a constant absolute pressure because of the difference between atmospheric pressure and the pressure in the manifold, however I could just be making this all up, but for some reason its there in my head.

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Question - is it even possible for these things to smoke, what with the DPF? Or will the DPF just clog?

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Good question but with major smoke problems like with an intercooler hose gone I can't see even the dpf filtering it all out but as you surely it would just clog up completely.

Sent from my HTC One using Ford OC mobile app

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Alright then, I guess the next thing to try after checking all the pipework is to T a boost gauge in to confirm there's definitely no pressure change in the manifold as I suspect and go from there. Hoping it's not turbo failure, I assumed not as there was no sudden noises just a lack of power but apparently the impeller shaft can shear with no signs so the inlet won't be driven at all which could be responsible. Hopefully not, I was hoping this car doesn't have the dreaded carbon buildup that's starved the turbo of oil especially after spending a lot on injectors recently!

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I'd check all of the boost pipe pre and post intercooler as there is a problem of these splitting. how many miles has it done?

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Sorry for the delay, only on around 78k I believe so wouldn't have thought pipework would be failing yet but you never know!

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