Jekyll & Hyde HDi

[Alan_M]

OK, looking for a few tips here....

My 306 is mis-behaving but intermittently, a jekyll & hyde nature. I've recently changed the MAF with genuine VDO and a refurbed throttle potentiometer. When it works, it goes very well (read, stays just about with a colleagues BMW E9X 320d Touring), at other times it sluggish as hell and smokes like a trooper. MPG has dropped to 40ish too, I was regularly getting 50mpg+ before the winter period.

Help.....

[Shawnobi]

Is your EGR blanked?

[Alan_M]

Is your EGR blanked?

Yep, and not leaking.

[Poodle]

Are there any other symptoms when this happens?

[Alan_M]

Are there any other symptoms when this happens?

Absolutely none.

Sluggish, MPG drops and chucks out dark/black soot on hard throttle.

Says to me that it's over-fuelling, so something is giving the ECU the wrong information intermittently. Absolutely fine yesterday and today.

I'm going to check the MAF and throttle potentiometer if the rain stops today. Other than that, how does temperature affect the HDi's? It's warmed up recently which coincides the car's improvement.

[Poodle]

Classic egr symptoms, not helpful lol.

I'm out of suggestions, seems you've already covered the prime suspects. Best way would be to get it on pp and see what's occuring.

[Alan_M]

Coming back to this, I've recently fitted a new battery to the HDi as I had the needle thing on start-up (earths all good). It's only been fitted for a day or two, but the difference in the cars behaviour is a real eye opener. Feels eager to go now and pulls harder than ever.

Anyone experienced a buffered battery causing running issues?

[powerandtorque]

Was it replacing the battery or merely the fact that you had the power disconnected thus resetting the ECU?

[Alan_M]

Was it replacing the battery or merely the fact that you had the power disconnected thus resetting the ECU?

Just replacing the battery, it wasn't off for long enough according to this procedure. Definate improvement though, accelerates with real gusto now.

I thought the general opinion of an ECU reset on the HDi's was fruitless (http://306oc.co.uk/forum/archive/index.p...29634.html).

Old battery still showing 12.6v, obviously not under load though. I'm going to rig up some leads from battery to cabin so I can monitor the charge on a meter.

[toseland]

get a socket one for the fag lighter socket... will moniter voltage as you need it.. ensure however there is a low amperage fuse in the line as itll catch fire and end your car pretty quickly if something goes bad,.