Surging between 2000 to 2750 ish

I have recently purchased a Synergy 2 and Peirburg MAF kit on eBay – I fitted the unit to my 2006 FL1 TD4 manual and the old girl was transformed. Two weeks later I have developed an issue and having read everything on your website and scoured landyzone I can’t see anything that fits. Would you be so kind to look over my notes below and pass comment or ideas as to what the issue may be?

With the car surging in normal driving (no power for 3-4 seconds, power for 3-4 seconds repeated unless very low throttle demand) becoming more noticeable under load. It occurs around 2000 rpm to 2750 rpm If I give it the berries from low revs and floor it goes like stink and has no issues and will hold 70mph + no problem. If I drop down to 50mph for instance in 5th gear I can’t get back up to speed because of the surging and have to give it some welly in 4th.

My confusion is that it doesn’t seem to be a fuel pressure issue as it runs great at WOT, boost obviously works again with WOT.


The engines had;

• Rebuilt injectors at a BOSCH approved place.
• New LP fuel pump and filter.
• turbo filter and crankcase vortexy thing

I have looked at all threads on here about surging but all seem quite different issues. Any thoughts much appreciated

Ideally you need to take a look at the live data, for HP fuel rail, LP fuel rail, MAP reading and MAF reading too.
With a Synergy fitted, you'll have an incorrect HP figure, and MAF figure but you'll be able to see the figures surging.
I suspect it's a boost issue, maybe due to a vac line being split. The turbo vanes are vacuum controlled, so that's where I'd look first.

Thanks Nodge - I'm unplugging the synergy and going from there. Had a quick glance over the vac lines from above but will pull off some plastic and have a poke around. I've got a cheap OBDII scanner and I've recorded some of the graphs whilst driving but can't pull up the fuel pressure. TPS seems fine and MAF, Boost and Intake readings all drop off at the same time.

ARCXJ said:

Thanks Nodge - I'm unplugging the synergy and going from there. Had a quick glance over the vac lines from above but will pull off some plastic and have a poke around. I've got a cheap OBDII scanner and I've recorded some of the graphs whilst driving but can't pull up the fuel pressure. TPS seems fine and MAF, Boost and Intake readings all drop off at the same time.

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It's a shame the rail reading isn't available, as it would be helpful to see if dropping rail pressure is responsible for the boost dropping off.

Unplugged the MAF and the problem has magically gone away but I now miss the Synergy effect.. Cleaned contacts with electrical cleaner to no avail. So good news I have a car I can use, bad is that something is amiss that is causing issues. I did notice during unplugging it that the spring clip I've highlighted is damaged and not holding, and the screw number 7 is missing... could be causing a vacum leak beyond the MAF?

Possible bingo - taken from the Syngergy 2 help sheet "Air leaks: Recently I was made aware of a cause of a return of poor low rev performance and warning light illumination, as if the nearly new Pierburgh maf had failed. It turned out that the U shaped duct which connects the maf housing to the turbo had worked loose progressively. This means intake air is drawn in, bypassing the maf causing it to give a low signal, just like a weak maf." - now where the hell would I find one of those clips?

If air is entering the turbo, bypassing the MAF, then the EDC will limit fueling, as part of its anti-smoke strategy.
So yes this could well solve the issue.

Everything crossed - I've asked a guy on the Freelanders facebook page who breaks loads of them to see if he has any, it's just the MAF housing and 1 bolt I need. It either got busted when I let halfrauds replace the MAF (Stupidly when I knew it wasn't the issue, turned out to be the Low Pressure Fuel Pump). Only thing making me dubious is that it ran fine for a week with the ronbox before having a fit. We shall see, least it's an easy thing to change and cheap.

ARCXJ said:

It either got busted when I let halfrauds replace the MAF

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Halfords. I wouldn't let those untrained monkeys fix my bike, let alone something complex like a diesel engine.

Trust me I when I say I was desperate - needed it to drive back home from work in that day.