Help with OBD data Ford Focus tdci underboost in high gears.

Help with OBD data Ford Focus tdci underboost in high gears.

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richard at home

Original Poster:

320 posts

119 months

Thursday 23rd February 2017
quotequote all
I have a 2009 1.6 Tdci focus which is throwing Underboost codes, but only in 4th gear.

I recorded some of the OBD data yesterday.

I can see that in first, second and third, there is loads of boost and good fuel pressure. Lots of air over the MAF too.

In 4th it just seems not to bother putting in any boost...

The turbo is a variable vane job and you can see that working in the low gears too.

The red line is where the DTC fault is flagged.

Any ideas what to look at?

I have cleaned the EGR valve. The fuel filter is about 6 months old. These cars do have an issue with turbo bearings failing due to clogged up oil feed pipe filters, but this one seems to work ok in the low gears.

Any help appreciated!


stevieturbo

17,270 posts

248 months

Thursday 23rd February 2017
quotequote all
Look at what boost control is doing.

Disco_Biscuit

837 posts

195 months

Thursday 23rd February 2017
quotequote all
Just go from 3rd to 5th, Don't bother with 4th.

richard at home

Original Poster:

320 posts

119 months

Thursday 23rd February 2017
quotequote all
stevieturbo said:
Look at what boost control is doing.
The turbo vane drive signal is on the chart. (in light green).

It appears to not be dropping to give more boost? I would assume it's operation is a result of inputs from RPM and throttle? I don't really know what is 'normal operation'.




Edited by richard at home on Thursday 23 February 18:27