Technical Engine revving out of controll !!

[steverich]

Hey Guys.
Ok. 10yearold multipla 1.9 JTD

Couple of weeks ago noticed revs stuck high when waiting at lights... cariied on and seemed to calm down,
Happened a couple of times since but thought nothing of it (cable sticking or something??)

However. Today, it went berzerk! high revs every time clutch depressed, even accelerating when not touching pedal.
After switching off and back on it starts ok but then quickly builds up to high revs again!!

Called RAC .... plugged into his little laptop.... it said it was doing about 400 - 500 rpm which apparently is not even idle speed. and the pedal sensor was saying 100% constantly.

RAC man was trying to pin it down to faulty sensor but said he couldn't be sure as the readings were not making any sense?!?
And No record of anything like it on their database. ?

anyone got any thoughts on this?

Many thanks.

Steve.

 

[MultiPa]

Sounds to me like the rev sensor has failed, so the car thinks it's idling at 400rpm (too low) and so keeps trying to make it rev correctly at 900rpm by increasing the revs, but keeps getting the data that it's revving at 400rpm, so it increases it again.

 

[steverich]

Yep. that's what we thought.

Took it in for diagnostic this morning (although it was running fine again??!?)
and it reported sensor fault.

The guy said would have to take the whole thing out, check all wiring etc and probably looking at £200 +

Does this sound right ?
To me it looks like it should be a real easy swap over job ??
or am I missing something?

And where is best place to get replacement sensor and how much should it be?

Cheers guys.

 

[widemouthfrog]

A cheap fix to try before you splash out on having someone pull it apart would be to get a secondhand throttle position sensor and try that. Is it one of these?

http://cgi.ebay.co.uk/2003-Fiat-Mul...arts_Vehicles_CarParts_SM&hash=item2a0e7c8b1c

That one looks pretty expensive to me.

 

[MultiPa]

If it was the throttle position sensor, wouldn't the fault occur in normal driving too? Or some sort of fault as the car would ocassionaly think the throttle position had changed?

Seems more likely to be the idle speed sensor or whatever it's called as it only happens at idle.

From reading this thread (largely about a petrol Multi, but some diesel input) could it perhaps be a rogue TDC sensor? https://www.fiatforum.com/multipla/116457-multipla-cuts-out-junctions-etc.html

This bit may please you:

Now thats out of the way the RPM sensor is about £30 but you need it lifted up on a ramp to change it so its not exactly going to break the bank.

 

[steverich]

Hey Guys.
Sorry didn't say,,, yesterday while it was happening it was trying to speed us up (without pressing accelerator)

Just spoke to garage, they say replacement part needs to be same part number or at least same 'year' and were reluctant to use anything from ebay.

He said it is revving high now (was ok when i took it in). wiring ok, but the readings only showed the sensor fault when it was revving normally??

New sensor from their suppliers (NOT DEALER) £170+ !!!!! WTF

And now he says glo plugs need replacing too!!
:bang:

 

[SGThirkell]

I'd go for the throttle position sensor too. Think they're like a variable resistor and if faulty show a constant value instead of changing depending how far down your foot is on the throttle.

 

[pig]

I remember that as a consequence of the Multi being a LHD design, there is a connector in the passenger footwell of RHD cars, linking the throttle potentiometer to the wiring loom. I believe it was a Fiat service fix to remove this connector and solder the two leads instead, because the connector had a habit of making bad contact. Might be worth looking at the connector and WD40-ing it as a test before spending any serious money.
Also ask the garage exactly WHY the glow plugs need replacing? Has the car ever failed to start in cold weather? My car has had the flashing glowplug light since I got it (indicating a dud glowplug) but has never failed to start, so ignore it.

 

[Zundapp]

Even if you live in Lapland your car doesn't need new glowplugs. As to the rest of your post, I reckon you need a different garage...

 

[steverich]

Hey Guys
Thanks for all your replys!!

Ok. you will be pleased to hear I have taken it out of that Garage!
Tried to charge me almost £80 just for plugging in a laptop! and then telling me he can't fix it !?? Unbelievable.

.........Obviously didn't pay it! .... settled at £30

Anyhoo. Does anyone have a detailed tutorial on how to change the throttle position sensoron a 2001 1.9 jtd ?

Would be MUCH appreciated :worship:

Cheers guys

 

[Zundapp]

As Pig has already suggested, the first thing to do is check and clean the connections at the throttle potentiometer. FIAT connections aren't the best quality in the world!

 

[sicone]

mine did the same .i have clean the connector and now it is ok,no money spend thanks to this forum:slayer:

 

[QinteQ]

Picture it, sitting in the driving seat, foot on throttle.

Now you have a LHS and a RHS glovebox. Under the RHS glovebox is the potentiometer. Under the RHS glovebox is a white connector.

If you follow the metal throttle to its top you will find a round metal thing with wires coming out called a potentiometer. These wires go directly horizontally left behind the radio and gear stick to a white connector under the LHS bulkhead where they connect to the ECU. This connector needs to be eliminated before even taking it to a garage let alone spending an English penny.

It may not be your problem .. .. but Fiat dealers make a mint charging parts when all they do is clean this connection. Give it welly with switch cleaner / good old scrape / rewire new spades in / whatever. Or just plug and unplug 6 times to make a good electrical connection, its this connector that provides all the info to the ECU that results in so many spurious error codes.

I made a post on this covering technical voltages and OHMS values a couple of years ago, I've no idea where it is but I'll find it if your stuck !

 

[QinteQ]

""""" Under the RHS glovebox is the potentiometer. Under the RHS glovebox is a white connector."""""

- should read .. ..

Under the RHS glovebox is the potentiometer. Under the LHS glovebox is a white connector.

 

[steverich]

Sorry Guys,
Forgot to post result:


Mr "charge £80 for plugging in a laptop and give you wrong diagnosis" said "absolutely positive it's the throttle sensor".

So almost bought new one for about £170 plus god knows what for fitting charge!,

BUT decided to have a go myself......

Traced wires to connector block, disconnected and re- connected a few times, sprayed with WD, .......... & whadda ya know..... FIXED !!! unbelievable!

All hail the fiat forum posters!!! you guys are great!!

Mucho thanks

 

[QinteQ]

Good, you are where I was a couple of years ago, I came here, read the info, doddle of a job.

Of course if you paid £250 including fitting & VAT it still would not have solved your problem. Its a known fact that many garage clean the ' said connector ' charge for the potentiometer & fitting and keep stumph.

- that's a net / nett proit of £450 and they are left with the £170 to resell to some poor unsuspecting muppett

 

[SkyeGospel]

Hi there. I am totally new to the forum and to Fiat ownership. I have a Multipla 1.9JTD and despite spending the first 3 weeks since buying it fixing all kinds of faults, I am absolutely loving it!!

Firstly, many thanks for the posts in this thread - I have been having the same problem of sudden, unexplaned revving (problem is there in normal driving as well as when static... car keeps on revving when clutch put in for a gear change) - intermitantly.

I have a question that has arisen from following the guidelines here. I have found the white connector and cleaned etc as advised - hopefully this will sort things, but just waiting as it was only intermittent and haven't had a chance for a good drive yet since doing that this morning. Hopefully problem solved without having to go further.

BUT when I was locating the white connector under the left hand glove box, I found another white connector - almost the same, but slightly larger - which had nothing plugged in at all. It got me wondering what SHOULD be plugged in to it??? Any suggestions? Am I missing something that should be plugged in there?

Many thanks,

Stuart

 

[steverich]

Hi Stuart.
yeah mine began as intermittent fault, then got more regular until eventually constant.

I think if I remember correctly I undin and 'WD'd' two connector blocks?
I'll have a look tomorrow.

Steve

 

[SkyeGospel]

Thanks for that - All sorted! Brilliant, I was imagining this being an expensive garage job!

 

[raineuk]

Mine did this . I cleaned the electric white connector in the passenger footwell and it cured the problem.