5000 rpm's with no throtle!

[dirtydirtydiesel]

Help!
It's not been a good day of my second week of 406 ownership! .
On my way into work this morning, ten miles covered & oil 'n' water nicely up to temp, two miles left to go I thought I'd give her the berries as I have put a bottle of Forte advanced formula diesel treatment into 35 ltrs of fuel. Well I exited a roundabout onto a nice bit of straight, changed into seconed gear & floored it, 3500rpm off gas, clutch in to grab third & wwooohhhooo!, instant 5000rpm. Let the clutch out & she's charging like a rampaging bull! .
Panic, turn off! coast for a bit reallise that I've not got the speed up to keep going, turn back on & wwooohhhooo! instant 5000rpm's again, Panic even more kill engine & coast to car park.
Bonnet up check throtle cable action, seems fine wiggle elec conector on throtle ass Try running again this time fine! & again twice more thoughout the day.
On run home got up to temps & floored it again, ? No Problem! W.T.F !
I am thinking It could be the throtle position sensor, anyone any ideas, it's not used any oil that's the first thing I checked.
Many thanks in advance Paul.

[lozz]

Hi,
Yeah it couid be tps related.

Have you got access to a code reader/diag
Might be worth having a plug in to see what flags up to save any guess work

[mjb]

There's two separate opposite-running tracks in the TPS (one returning up to 12v with increased pedal movement, one which goes down to 0v), so in the event of a dirty track or broken wire, the ECU can tell if something's amiss and restrict the engine output to the lesser of the pedal positions indicated. However, this is obviously not the case here.
If the car were burning its own oil, turning the key off would have had no effect and you'd have had to stall it. It'd also (being purely self-running) not restrict itself to 5000rpm.
The HDI adjusts engine speed primarily through varying the duty cycle of the injectors. You'd know it if one jammed open, and It'd take all 4 injectors to jam open to cause a redline in 3rd, and again the rev limiter wouldn't apply, but the engine management and stop lights would definitely come on.

So it comes down to the car thinking it's running correctly. The only thing I can think of that would cause this either the throttle cable got jammed (did it feel normal?) or the arms inside the TPS detached themselves and got stuck in the full throttle position. This can be verified using PP2000 while it's happening (ignition on, engine not running).

I'd suggest checking the cable and replacing the TPS. You can get one for £20 on ebay, which is cheaper than paying someone for a diagnostic session which will only be useful if the problem occurs again.

[dirtydirtydiesel]

MJB,
Thanks for the info, as I said second thing I checked was the oil level ( to see if it had used any ) I do know a bit about diesels & knew that because it stopped @ 5000rpm & turned off that it was not running on it's own sump oil.
Anyhow not sure yet if the floor mat interfered with the throtle or if it's the TPS, it's not done it since ( 3 more run's trying to simulate the conditions! ) the floor mat will be secured & I have a code reader. So then once that's done will leave it untill / if it does it again then will replace the TPS.
Many thanks for your imput Paul.

[scotty73]

It happened to my car 3 times last year but only when the wife was driving, what i have noticed though is every time i drive the car i have to rescue the mat back down to floor level it seems to want to investigate what's going on behind the dashboard.

Coincidence? i dunno.

[Busman]

My original hdi did this once and never again. Consequentially I never did find out why. Although the mat could well be involved.

[TheSongRemainsTheSame]

My mom took her car to the dealer for this. We made sure to mention it a lot at her birthday:)

[mjb]

haha been there done that too