Trip computer reads 9.4mpg

[davet]

2001 406 Exec HDi 110 Estate.
I had problems with the fuel lift pump, it blew a relay then the fuse, so I had the pump replaced, I hoped it would also fix the problem described below - but it hasn't
When things started playing up the trip computer went haywire, it rarely shows any fuel consuption at all, when it does it shows 9.4mpg, I know I'm doing around 45mpg also the fuel gauge has become erratic. I think it is something in the ECU, I tried re-setting everything by disconnecting the battery for 10 mins etc, but still no luck.
Any ideas as to how I can re-set things out there?

[Doggy]

I'm wondering if it might be to do with the speed signal.

If you reset the trip while doing say a steady 30 mph, does the indicated average speed seem correct?

[davet]

Hi Doggy,

The average speed and mileage readouts seem to be ok. 50 mile round trip - 1 hr 20 mins 37mph average - not far out.
I've done a little web trawling and thought it might be a problem with the "Built in systems interface" - any thoughts?

Cheers - Dave

[Doggy]

I don't know this for a fact, but I think the trip computer function is provided by the engine ecu, which 'knows' how much it is injecting, (unless you have one of those diesel tuning box gadgets fitted), it also 'knows' the road speed for the cruise function and presumably integrates the distance covered.

The MFD is driven by the BSI, so anything's possible.

Try a BSI reset, as described here: viewtopic.php?f=10&t=10968

Failing that, can you find someone local with PP2000? This should enable you to monitor most of the raw data, (speed, injected volume etc), but you would probably need to compare it to a 'healthy' example to tell what's different.

[davet]

I think that the series of problems has now been resolved. This started with the fuse that supplies the fuel lift pump etc blowing, also the fuel gauge and trip computer were giving inconsistent readings, which I wasn't too worried about. The fuel pump relay was replaced, the pump was replaced, many many fuses were replaced I disconnected the EGR (it has been blanked off for years anyway) Following advice from this forum I was going to try a BSI reset to cure the gauge and TC problems, but never got round to it.

Eventually the car decided it was going to stop and not start again while reversing off the driveway (great timing) and I got an Auto Electrician in. It turned out to be chaffed wires in the loom near the ECU box, he repaired that and everything seems to work fine now including the fuel gauge and TC (I can almost hear the fuse waiting to blow as I write this)

Thanks to the forum for the advice and a big shout out to Clive at CLG Auto Electrics in High Wycombe, not the first time he's done work for me (probablly not the last) and good jobs in my son's car too - Good Guy!

2001 Peugeot 406 110HDi Exec Estate
Trip computer now saying 52.4mpg - Odometer 200500!

[steve_earwig]

Wow! Good news that it's all as it should be, although I have to ask where abouts was this chaffing? There's a lot of HDi drivers out here suddenly paying a lot of attention...

[trufflehunt]

Wow! Good news that it's all as it should be, although I have to ask where abouts was this chaffing? There's a lot of HDi drivers out here suddenly paying a lot of attention...

I certainly am.

[davet]

Don't panic!
I didn't see the actual chaffed wires, cos' I was at work earning the money to pay for auto electricians. Where Clive repaired the loom was just outside the entrance to the ECU box, so its easy to check whether you're developing the same problem.

BTW for the last 30k I have been adding 300ml of two stroke oil to each tank of diesel. It definitely makes the engine run smoother and quieter, it "picks up" more cleanly and there's no sign of soot on hard acceleration (shame when you want to punish a cyclist for holding you up for the last five miles ). I don't think the car is actually any faster or more economical, but it feels so much better to drive. It makes the low sulphur crap that they sell nowadays feel like the old stuff. Dare I say it? - without the additive my HDi feels like an old VW PD, with the additive its smooth, quiet and torquey, like it should be.

[steve_earwig]

Mine looks mint there (I have pšhotographs to prove it, rather than pulling the car apart again), maybe it's possible for the wires to chaff on the conduit? It must be connections between BM34. Unless the car is semi-skimmed. Not to worry, I won't gril you on RPOs as, as you said, it's easy enough to check.