Speedo and lack of power

[Tyred]

Hi all. I have looked around the forum and seen plenty of posts that dont quite match the problem I am having.

My 2008 1.6 HDi van runs really well most of the time. It now has 172k on the clock and has been serviced at every interval. In general it runs smooth, no smoke and pulls well.

However!! Now and again the speedo stops working, needle falls to zero and there is a distinct lack of power. The engine still runs well, although I have to put a lot more revs on and change down on hills. No warning lights and everything else appears to work fine. Then suddenly it bursts back to life and the speedo works again and the power is there.

This can happen several times a day or not at all. I make deliveries in it and cover 330 miles a day mostly 5th gear cruising.

At its recent MOT the only thing they advised me on was that the exhaust was a bit high on omissions and they advised me to give the engine a good "thrashing" now and again

Any idea what this annoying problem could be?

[Modmytop]

Speedo on my 2.0 HDi MSpace also drops to zero from time to time. However, have always found engine seems more responsive when it happens!

[3rensho]

Any error codes display on a reader??

[Tyred]

Any error codes display on a reader??

Sorry I dont have access to a reader. I'll ask at the garage but its a small independent and I doubt he'll have one but you never know. When I mentioned the problem to him he said he'd have a look. Van going in for a service on Saturday. I just hoped I'd find someone on here who recognised the issue

After it happening 3-4 times yesterday the van ran smooth as silk all day today. As was mentioned elsewhere on these boards when its an intermittant problem like this its hard to diagnose from scratch.

Thanks for the replies

[addo]

I can think of two things possible; one is a poor signal from the output speed sensor (this drives the speedometer among other things), also a blocked/failing paralytic converter might be part of the fun.

[Tyred]

Well its been in for its service and no they do not have a reader and they cannot replicate the problem. So thats 3 days now that it has not happened. Fingers crossed. lets see what the week brings

[Tyred]

Picking up on what the MOT guy said and the suggestion of addo above I gave the engine a good workout for a couple of days, cruising at speed rather than for economy and driving in 4th instead of 5th on a hill I go over. Cant say I noticed any emmissions but since doing this the symptoms I described in the OP have stopped and its running fine again. So from now on every few weeks the engine will be gettig a raz

Thanks for the replies and suggestions.

[dumdum]

does the car have abs, if so then you may have abs/communication on can network issues, a decent lexia operator will consult the faults log in the bsi and it will reveal communication faults if there are any

[addo]

There's always a bunch of "knock on" faults there; you get things like temporary loss of engine speed signal and it's no guarantee the VSS is duff. I think a lot of the faults logged I see, are from dying batteries that have internal shorts and this briefly affects the sensor reference voltage control.

[stuartinlancashire]

Is it just the speedo or does the rev counter drop to? When the speedo unit looses power all the needles reset to zero when power is restored so if it's doing this then I'd be inclined to take the speedo unit out and make sure the plug on the back isn't loose, to be fair it shouldn't be as it should be locked in place but worth checking.