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Discussion Starter · #1 ·
I'm no nearer to getting to the bottom of this issue - noticeable flat spot/hesitation between 2-2.5k revs in lower gears.

I've got FORscan on my laptop, and the appropriate ELM cable, so would like to log various 'gauges' in a live environment. Can anyone recommend which sensors to log given the symptoms, as I've no experience with turbo setup. I'm making an assumption that I can run the car and then examine the historical data?? If this is not the case with this software, what should I be using?

There are no apparent DTC's , and I've cleaned the MAF and replaced the air filter (standard fitment). Car is stock.

It definitely feels like a boost issue...

TIA,

Ian
 

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I'm new to this engine, and struggling to know which pipe(s) to check - all seems to be going on behind the block?? Still has the symposer fitted.
If you still have the symposer I would be looking there immediately if you suspect a boost leak! They were renowned for failing & splitting creating boost leaks which is why the vast majority of people got rid of them. Given the ages of the Mk2's now if your diaphragm is still in one piece I would be amazed. It is very easy to open it up & see the condition of things. If in doubt it can be temporarily blocked off to see if it cures things. If it does you can either fit a new one - or just pull the whole thing out & block it off properly.
 

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Great, before the logging I would still try to disconect the negative battery terminal for 1 h to have a clean start.
Then if you can go for a drive with a codriver which would hold the laptop wih forscan logging so he could read the values to you the exact moment when you feel the hesitation...
 

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Discussion Starter · #11 ·
OK, so I've managed to get a couple of logs when the issue was apparent. I'm no expert, so not really sure what I'm looking for, however, there seems to be a big drop in the MAF voltage and g/s at the time of the flat spot. Other than that, I can't see anything obvious...

Values at 12:55 secs - this is the lowest MAF voltage

Rectangle Font Parallel Number Screenshot


I'd attach the raw file, but it looks like it's a non standard file extension, so not allowed...so I've posted to my dropbox. Use this link:

FORScan Test File

Many thanks, Ian
 

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Was hoping you would drive it a bit through the whole rpms and with a bit of boost so we can see how the fuel trims, boost, maf, etc behave

Which year is stamped on the maf sensor when you cleaned it?
 

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Discussion Starter · #16 ·
I’ve been having this issue with my mk3 focus rs. I removed the Dreamscience map and put back to factory now it’s pulling smoothly again 👍🏻
This is interesting. The car has a Mountune badge on the rear, but I have no paperwork or evidence to suggest it has been mapped. I wonder if it's a problem similar to yours...I've only ever driven this ST, so nothing to compare with. IS there any clue in the FORScan data that might indicate if it's been altered??
 

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Discussion Starter · #18 ·
Good news, finally got the symposer off and a new pipe/alloy bung installed. Had to use a dremel drill with a cutting disk to get the clip off.

Now the bad news - made no difference, in fact I'd say it was worse.

Think I need some professional help.
 
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