406 Hdi 110 hp low power below 1000 rpm

[Peter.N.]

Goes like a train over 2000 rpm but below 1000 I sometimes have to turn the aircon off to pull away on a hill. I changed the cam belt last year and couldn't get the adjustment on the cam shaft hub where the book says it should be, although the peg goes in OK. Other than that I'm stumped.

Replaced the vacuum pump sometime back and that improved the 1500-2000 rpm band and you can feel the boost come in at about 1500 and at 2000 and above is everything it always was. Changed the MAF from the other car, makes no difference although that one pulls OK.

Any suggestions? Thanks

Peter

[moizeau]

Peter, I'd love to help you more but..... Below a grand, uphill I need revs or the aircon off with the 2.1td, same goes for a fast getaway uphill. Have you compared 'live data' between the two cars? I'm sure I'm trying to help someone who knows far more than me!

[white exec]

Peter,
What happens if you put car on the level, use 1st gear, allow car to tootle along at idle speed (850-900rpm?), and then floor the throttle?

[Peter.N.]

Seems to pull away OK on the level Chris although when I take off from outside the house with the gradient on the track, when its cold and particularly in cold weather it tends to stall.

Moizeau.

The other car doesn't seem to have a problem although the aircon doesn't work on that one but it doesn't stall when pulling away in cold weather. My 2.1. XMs with the Bosch pump would pull almost from tickover and were smoother than the Hdi's.

Peter

[white exec]

Sounds like lack of fuel (under-fuelling). When cold, diesels often show more power than when warmed up.
Unable to help you with HDi, but someone surely will.

[Peter.N.]

Thanks Chris. Have changed the filter and the DMF to no avail. In normal driving you don't notice it but it just catches me out now and again. If you are going up a steep hill if the revs drop below 1500 you have to change down smartly or it will stop - weird. I'm going to check the camshaft timing just in case as it I only seem to have noticed it since I changed the belt, but once over 2000 rpm it flies.

Peter

[Paul-R]

DMF? Do you mean the MAF Peter?

A bit extreme if you don't...

[moizeau]

If the other car's AC doesn't work can you not turn off the AC in the problem car and do a live data check and compare the two? I'm sure Marc or someone else will correct me if I'm wrong but I was under the impression that the 406 comes with two sizes of AC compressors, possibly 90 and 110 . My 406 doesn't like pulling from low revs (tickover, no accelerator) with air con on or lower than 1800 going up a steepish hill. At any speed without it it's like diving an auto. 5th gear from 30 upwards. Just thought the live data with two comparable cars may give you a clue?

Pete

[Peter.N.]

Yes sorry Paul I do mean MAF, senility is setting in.

Pete

I would if I could get either of my PP200s to work, but I can't. I first noticed this reluctance to climb hills at low speed when we went to Yorkshire last year just after I had fitted a new cam belt, I crossed a bridge and the road turned sharp left up a steepish hill and I had to change down into first! The aircon really knocks the performance, mind you I recently regassed it and its now very cold. I have just got back from Newton Abbot and had to turn the aircon off on most hills, I did have a lot of weight in it mind.

Peter

[moizeau]

Any news? The AC pump runs on bearings I presume like an alternator, once the clutch is engaged? Could it be that the internals in the compressor are holding the motor back on low revs. I doubt it unless the aux belt is showing signs of damage? Ask the air con experts perhaps? Can you find someone with a diag that works?
Pete

[Peter.N.]

I don't think the aircon is the problem its lack of output from the engine at low revs. When tested against the other almost identical car - even the same colour! the other car Pulls away better, this one sometimes stalls when pulling away on a gradient if cold, putting on the aircon just makes it worse.

Peter