seems to run better in the winter time , assuming as the air is colder the engine and turbo prefer that ??

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Nodge68 said:

My TD4 only does ~30 Mpg. My daily commute has a mix of hills, duel carriageway and slow flat road. I'll see how this new MAF effects Mpg, because I'm well down on Mpg by comparison to others. I use an app to calculate my fuel usage to 2 decimal places.

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Joe_H said:

Not a lot really - well, ok - it does trick the ecu into raising the HPFP pressure - it also does a basic compensation for anyone that fitted their oft' touted pierburg MAF (WHY ? when others are available - but anyway //// you can have MAF amp on - which is of absolutely no use at all on it's own if the maf is working ok (It is a basic form of increasing fuelling -- - or you can have HPFP fudging to give a higher fuel pressure in the common rail giving more fuel per injector opening cycle. (a slightly better and more positive approach)
Combining the two can give you some slight benefits. - yet none that would really be noticeable. The unit is basically a fudger of the HPFP sensor with an 'added' maf amp unit. MAF issues on TD4's are really NOT that common - you only here of a few bad ones - not the multi thousands that are absolutely fine.
All the settings do are alter a small addition curve for fuelling - all the high low med power torque etc is mostly utter BS. As mike said - and others - turn the knob and see - if it feels wrong back it off.. It is a rough compromise with little finesse.
However for most it does the job - it will NEVER save you fuel - ie - it will NEVER increase MPG - only your right foot will do that. It has no control at all over the VNT turbo - which is a let down... it is a good basic fudge.
The two units are sold int he same box to try to add value when in fact - if the maf you have is ok, the maf unit settings do nothing.

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Panic Over said:

I've just bought a 2001 TD4. I was planning on doing the egr mod. Then the ronbox and maf, only because I've read that it would improve mpg. Would you suggest that I keep my money in my pocket?

I do drive like miss Daisy

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Nodge68 said:

In theory adding more fuel will reduce MPG.
The Synergy does have an economy setting. This theoretically must reduce fuel throughput and improve economy.
My TD4 SE auto does just under 30 Mpg. However I don't drive like Miss Daisy. My synergy is set to 8 with MAF compensation turned on.
Fitting the Synergy made no difference to my MPG, but a big improvement torque. So for me, it was worth the outlay. I also have the Ron supplied Pierburg MAF, although I've not fitted it as yet. I am trialing a £25 , (now £27) Ebay MAF.

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