Hi guys

I have a 2011 (MK 2.5) ford focus 1.6tdci, it's recently started having a boost problem at around just over 2000rpm, it's quite hesitant to get on boost (Especially in fourth). The revs seem to stick at around just over 2100 and it seems like the engine is hesitating to get on boost. The strange thing is if I lift off the throttle and then re apply it, it boosts fine (sometimes). I've had the engine malfunction warning come up as well as the EML and when plugged in to an OBD reader the P0299 (turbo underboost) code shows. I've just serviced the car, changing all the filters (including fuel) and fluids, the only thing that I didn't change is the glow plugs, as I read that if the car starts fine and idles fine, then not to bother as it can be a right S*****r of a job! But the problem remains! The turbo sounds fine and the engine isn't smoking. I'm not sure what it is exactly but to the left of the engine there is a pipe with some electrical connectors which in my case, is covered in what seems to be carbon! Or old dry oil. I'm not sure if this has anything to do with my problem, but I would be interested to hear what it is (if you would like me to upload pictures then let me know). Does anyone have any idea what it could be? Would the OBD reader pick up a code if the EGR was shot?

Thanks Guys.

5 hours ago, Sainz1992 said:

 Would the OBD reader pick up a code if the EGR was shot?

Yes, if the EGR was badly malfunctioning, it would trigger an EGR code. But for minor errors, like it is not quite closing properly, then the ECU may not see the error. EGR leakage or failing to close can cause Turbo underboost errors.

On the left (UK driver's) side of the engine is the air intake from the intercooler to the inlet manifold. In this air intake is a throttle valve, and probably an intercooler bypass valve. If the throttle valve was not fully opening, it would cause underboost.

The most common cause of underboost is holes or splits in the intake pipes and hoses from turbo to inlet manifold. These can be difficult to see, they are usually hidden in the worst location. It is that Law again!

The next option is the turbo actuator system. Earlier 1.6TDCIs used a vacuum actuator, with a solenoid valve at the back of the engine, piped to the turbo actuator. Later ones may have an electrical actuator. Either way, it could be the vanes sticking in the turbo, or a fault in the actuator.

15 hours ago, Tdci-Peter said:

Yes, if the EGR was badly malfunctioning, it would trigger an EGR code. But for minor errors, like it is not quite closing properly, then the ECU may not see the error. EGR leakage or failing to close can cause Turbo underboost errors.

On the left (UK driver's) side of the engine is the air intake from the intercooler to the inlet manifold. In this air intake is a throttle valve, and probably an intercooler bypass valve. If the throttle valve was not fully opening, it would cause underboost.

The most common cause of underboost is holes or splits in the intake pipes and hoses from turbo to inlet manifold. These can be difficult to see, they are usually hidden in the worst location. It is that Law again!

The next option is the turbo actuator system. Earlier 1.6TDCIs used a vacuum actuator, with a solenoid valve at the back of the engine, piped to the turbo actuator. Later ones may have an electrical actuator. Either way, it could be the vanes sticking in the turbo, or a fault in the actuator.

Cheers mate, I'll take the EGR valve off first and give it a clean to try and eliminate that. Ill take a look at the throttle valve too because that pipe is absolutely caked in carbon deposits! When I was servicing the car I looked at the intake pipes and hoses but I couldn't see any cracks or splits and I don't hear any "whooshing" or anything when revving, so hopefully there's no hidden leaks. I'm hoping its not a turbo issue! I'll keep the thread updated through my trial by elimination!!

Cheers man

Update..

I took the EGR valve off today and gave it a good clean as it was pretty sooty! At first the valve was pretty sticky, but after a good dousing with WD the valve freed up and was buttery smooth... Unfortunately though, it didn't solve the problem.. Next up, the throttle valve.

Good news and bad news...

Good news first.. it's fixed! I opened the bonnet one day as the engine was idling weirdly every 3 seconds or so the revs would drop and then go back to normal. On looking at the engine I noticed that the waste gate was opening in sync with the revs dropping, it would open, go down half way and then close completely and then repeat. On looking through a thread on here I saw that someone had the exact same signs and said that it was a result of a failed pressure converter valve (AKA boost solenoid) so £50 later and a 1 hour diy job the car is sorted!

Now for the bad news.. The bonnet catch is broken and now I cant open the bonnet!