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Increased tick over speed


Thewad

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Evening people, hope someone can point me in the right direction please, fiat ducato x250 3litre 160hp

As title I have this 'problem' where the tick over speed increases all by it's self it's cause me no other effects van runs perfect apart from this.

I can start van leave ruining and it may or may not happen, I can be running for a hour or so and nothing no set patten, but when it does it increase to about 1200rpm and stays there but strangely if I turn off and restart it clears itself and may not do it again but then again it may within 15mins ?

Hopefully I have explained clearly and some one can help

 

Thanks :-D

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There was an article in MMM about Ducatos in general. One thing that was flagged up on the 3.0 was the increase in tickover rpm and often caused by the earthing strap between the engine block and chassis breaking down.

 

Details on where this strap is and how to replace can be found be searching the Ducato forum http://www.fiatforum.com/ducato/

 

If nothing else, many 3.0lt owners replace this earth strap with something like this http://www.halfords.com/motoring/bulbs-blades-batteries/car-battery-chargers/halfords-negative-battery-cable-45cm-18

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Most engines respond to demand from alternators if they sense a a power drain, but this sounds a little too severe an increase in revs. There are some very clever people on this site and by tomorrow someone will be able to give you a better diagnosis.

 

I see someone clever got there before me!

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Found this,

 

Hello Campers,

 

We have had some strange electrical faults over the last few weeks and I would like to bring the symptoms to your attention, and a fix for it!

 

Our X250 vans dating from 2007 have now covered betreen 150 and 200,000 miles and while your vehicles will probably never reach that sort of mileage (unless adapted for space exploration) I think that the fault is just as likely due to age as mileage. It could potentially affect any X250 with any engine fitted.

 

Symptom.

 

Engine idle speed alters from normal 850 to 900 rpm to 1400 to 1500rpm. Engine management light may come on. Often the fault will only appear when the headlights are on.

 

Cure.

 

This is a typical sign that the alternator output is too low and the engine is increasing revs to counter this. Many vehicles do this, but with the X250 it is not the case unless the battery warning light is also illuminated.

What is actually happening is that the earth strap to the gearbox is offering too high a resistance and is not allowing the ECU enough power, particularly when other devices are pulling more current (such as the lights), and this causes the ECU to try to overcome the problem while also going into protection mode with engine output.

 

We have removed and cleaned several of these earth straps and have not been able to improve things. The only solution has been to fit a new earth cable, which we have had made up for us by a local auto electrician. The original Fiat cable is of poor quality braided cable; exposed to the elements. Our new ones are plastic coated and have solved all of the problems encountered so far. (6 out of 20 vehicles of that age)

 

In summary:

 

If you think you have a problem, seek out an auto electrician and have the earth cable replaced. Do not waste time and money going to Fiat dealers or anywhere else for that matter because they will try all manner of tests and fixes before arriving at the same conclusion.

 

This is not intended to scare you, but I did promise to keep you up to date with problems that we encounter with our fleet.

At worst the problem is inconvenient and could prevent starting of the engine and blown battery fuses. There are no safety implications that we have been able to identify.

 

Merry Christmas.

 

Nick

 

 

Edited by euroserv 2010-12-02 11:26 AM

 

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I've heard that owners with this type of engine have had to replace the throttle body.

 

I don't know what the symptoms were to prompt the replacement of this item but I guess it was related to irratic engine speed of some kind.

 

Perhaps others will know more about this.

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Euroserv (Nick) is on the ball with his old post. We doubled up on earth cables and fitted a second one as a belt & braces job.

 

Our symptoms were slightly different - sometimes the engine wouldn't start from hot, wouldn't even crank over and all the dash lights flickered. Disconnecting the cab battery for a few seconds resolved the problem but we never knew when the gremlins would strike again. The cab battery was in good health but since changing to new earth cables some months ago, all has been fine.

 

IIRC, a throttle body problem will give more issues than just high tickover rpm and may throw up the EML light and error codes if checked with a scanner. As an aside, our 2013 Vauxhall Insignia also has periods of increased tickover but this has been attributed to the DPF doing a re-gen.

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Thank you for info everyone, I am going to revisit my earth strap and double check here first. I will keep you updated.

Thanks for reminder of Adams Morley , may go this route if no luck , the alternator theory is also striking a cord as my battery always seems to sound 'flatish' on turn over ,it sounds the same if left for six weeks or six days even after a long run it always sounds like it's struggling. (New stater also fitted) :-(

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Hi,

We had same issue ie inctresed tickover speed and when checking alternator output at the cig lighter there was no increase in voltage with engine running

 

RAC called out and advised that the alternator had failed and we would need to replace it and he would follow us to the nearest RAC approved garage

 

I declined and decided to look at the costs involved (I had already fitted additional earth strap as per Nick)

 

Google/Ebay provided the answer re failure of Bosch alternators stating that 95% of problems were a failure of the voltage regulator a £15 five min fix (Alternator on the bench)

 

It took me a couple of hours to sort out what I was doing and how to replace the voltage regulator

without the massive task of removing the alternator but once finished the tickover and charging were

back to normal

 

I now have a spare VR in case it fails again and think doing the job again would take around 30 mins

 

Regards and merry Xmas to all

 

Ray

 

 

 

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Airstream - 2015-12-17 12:50 PM

 

Hi,

We had same issue ie inctresed tickover speed and when checking alternator output at the cig lighter there was no increase in voltage with engine running

 

RAC called out and advised that the alternator had failed and we would need to replace it and he would follow us to the nearest RAC approved garage

 

I declined and decided to look at the costs involved (I had already fitted additional earth strap as per Nick)

 

Google/Ebay provided the answer re failure of Bosch alternators stating that 95% of problems were a failure of the voltage regulator a £15 five min fix (Alternator on the bench)

 

It took me a couple of hours to sort out what I was doing and how to replace the voltage regulator

without the massive task of removing the alternator but once finished the tickover and charging were

back to normal

 

I now have a spare VR in case it fails again and think doing the job again would take around 30 mins

 

Regards and merry Xmas to all

 

Ray

 

 

 

Hi Ray,

 

Can i ask if the battery warning light was illuminated? You did not say so, and this is usually the crucial difference between an earth fault and an actual charging fault where the revs have risen at idle.

 

Thanks

 

Nick

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I do not have a ign warning light on , so far , but having searched on various forums over the last few days two things keep cropping up as already stated earth strap/s or alternator so I will start again to look at van at the weekend.

 

 

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You have said that the problem is intermittent so the normal test is difficult to carry out but if you end up with a situation where it is happening every time that you run the engine you should do the following;

 

With the engine off, attach one end of a jump lead to the earth point under the bonnet and attach the other to the lifting eye on top of the engine. You only need one of the leads. Do not attach the other lead to anything. Make sure that any loose leads are not going to foul any moving part such as the radiator fans.

 

Start the engine, and if the revs do not increase; you have a poor earth. If it makes no difference, you probably have an electrical fault close to the fusebox but it is very unlikely that the alternator is at fault; it hardly ever is, and would have illuminated the battery light on the dashboard anyway.

 

It is probably a good idea to carry a set of jump leads with you so that you can do this test while out and about if the problem occurs again in a random manner!

 

Best of luck.

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Morning campers, picked up motorhome to look at earth straps etc, drove the 5 miles to home no problems left running for a while again no problem.

Removed earth at battery end looked perfect if I am honest but never the less cleaned with emery tape replaced.

Now under the bonnet to completely remove existing and new earth strap, where strap bolts to engine mount I throughly clean to almost a polish same with strap ends lightly greased and replaced all going according to plan. :-D

There is no 'but' I am pleased to say when I stared van I was pleasantly surprised at how much quicker the starter motor turned it always sounded a bit lazy, and so far,after long road test no increased tick over so as it stands mildly optimistic that my problem is cured, will update in due course for you all

 

Happy Christmas (lol)

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  • 2 weeks later...
Quick update, on my increased idle speed, 80 mile around trip today no problems what so ever looks like a nice easy fix 'clean that earth strap people' not only does the engine turn faster on start idle has sorted it's self out but I did have EML come on at start up, no more all completely cleared up, thanks for all the advice :-D
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We have had erratic idle speeds on these vehicles both lower, to almost a stall, and higher, all sorted with new Earth straps. Even though the old ones looked Ok.

 

After resolving yet another problem with a live Headlight feed cable on a Citroen H van where the cable had become corroded between two strips riveted together it made me wonder if the Fiat cable had a similar issue.

 

So I dug a Fiat cable out of the scrap bin and examined it really carefully, there were no outward signs of any issue. I then got a cutting disk on one end and opened up the connecter crimped onto the Copper cable. It was a mess of green and white. Not surprising there was no current flow.

The other end was also corroded where the connector (steel) is clamped over the copper braid, but not as bad.

 

We think the cable design is such that if it is constantly sprayed with Salt Water it will run through the braids into the joint and start corrosion.

 

Everyone has identified the earth cables are an issue and that cleaning them is a waste of time but not seen any explanation as to why, so dead chuffed that we may have identified the reason.

 

Obviously the contact points on the box and chassis must be good as well, but we think that any crimped connecter to Copper cable will eventually suffer.

 

We suggest anyone still with an Earth strap of this type should replace it, as it will degrade sooner rather than later. The initial problems may be a lower charge rate, or some other restriction to passing current, but it is likely to worsen.

 

Tried posting pictures, but this Forum has well documented picture posting issues, so put them onto the bottom of a Citroen H van electrical page : http://www.citroenhyonline.co.uk/6volt-to-12volt-conversion.php

The Citroen vans we restore as camper vans were made from 1947 to 1981 so pretty prone to corrosion, I should have twigged before the Fiat Earth cable cause as I have seen it so many times.

 

 

We are going to trial a Braided cable without crimp on connectors that we think should last much longer, see web page above for info.

 

I have updated the older thread on earth straps as well.

 

 

 

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Seems it may be an inherent problem. The problem is a galvanic reaction and our damp climate. Copper and zinc (the galvanising of the van bodywork and the crimp on connectors) are far removed on the galvanic series, meaning they generate an electrolytic current in the presence of moisture, as a consequence of which the copper is eroded. So, too, are copper and steel (what lies under the zinc). The copper is sacrificial in the presence of moisture, and especially salty water (think winter roads). So, electrolysis ultimately destroys the copper.

 

Aluminium cable would be much better from this point of view, but has higher resistance and is also more prone to direct corrosion in the presence of moisture/salt water, so would probably (if one could get it!) suffer much the same fate but for different reasons.

 

The best one might hope to achieve would be to seal the copper into galvanised steel crimp to exclude any chance of moisture ingress, completely insulate the copper cable, and re-site the earth strap in as dry a location as can be found. Maybe battery cables would offer a better solution, as they are insulated. One then just has to fully waterproof the crimp without destroying the insulation on the cable.

 

Tinning the copper seems to offer little potential advantage, as it is still too close to copper in the series, and so still prone to the same (though at a reduced rate) process.

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Hello Brian, if you have a look on the website using the link above, there are photos and details of what we think might be the best solution?

A cable with no crimp connectors at all.

There is also a link to a company on ebay, not used them so don't know what they are like, that sells the stuff at just £3 a 12"/300mm strip, so probably the least expensive option too?

 

We have ordered some heavy duty Braid and will make up some earth cables then present them as an option to the Motorhome owners that we get in for a Habitation Check/Service and see how they fare.

 

Classic cars have them fitted, just a Braided cable 'strap' with a hole in the Braid itself. No crimp on connectors at all.

A variation also used on the Classic Citroen H vans we convert to Campers and they work well, some over 65 years old from the 1940's, when not replaced by a modern version.

 

See a photo of what we mean at the bottom of this page here : http://www.citroenhyonline.co.uk/6volt-to-12volt-conversion.php

 

 

 

 

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