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General >> Problems >> Engine Idle problems
(Message started by: st.eve on Feb 9th, 2010, 11:46pm)

Title: Engine Idle problems
Post by st.eve on Feb 9th, 2010, 11:46pm
This post is about an engine idle problem – Scorpio Ultima 2.9 12 valve (manufactured Nov ’95). Sorry folks but it’s a bit of a long winded story.

Further to a previous post regarding electrical gremlins, ignition light, oil light and cooling fan coming on when the ignition was switched off, the problem was located to a length of wiring loom on the near side in the engine bay running from the bulkhead towards the front of the car below the coil.

The garage said they could repair the section of loom, which they did. I collected the car and everything seemed fine till I got just a few miles down the road when the starter motor kicked in whilst driving with all the dashboard lights going on and off and smoke coming from under the bonnet. I switched off the ignition but nothing stopped.

I acted fast, whipped off the battery cover and set about disconnecting the battery. By now the terminals were pretty d**n hot and a couple of burnt finger tips later got the negative terminal disconnected and the wiring gradually stopped burning.

The garage had left part of the loom unclipped which was resting again the exhaust, melted through and shorted out.

Managed to separate the wires, tie them back and return to the garage. They repaired the damaged cables and secured them.  

Everything seemed ok but after driving the car only some 15 miles, I then started having idling problems. The revs would drop very low when stationary and the engine would sometimes cut out. It restarted without a problem. Over the next few miles this got progressively worse with the engine cutting out every time I stopped.

Booked the car back in to the garage for a few days later. In the mean time, it was undrivable. On the advice of an AA patrol, I dismantled the idle control valve and soaked the mechanical half in petrol overnight and carefully tried to remove any carbon deposits, refitted the valve but it had made no difference.  On the morning that it was booked in to the garage, I drove there keeping the revs up, pulled into the garage and stopped the car. You’ve guessed, the revs returned to normal. Anyway, realising that the fault now seemed intermittent, I left the car for testing. They had it on the computer which revealed no faults and they test drove it, still no fault, so they rang me to come and collect it. I drove out of the garage, had no indicators. Drove back into the garage only to be told, “Oh that was the first thing we noticed when we test drove the car”.  Well they sure as hell were working when I drove into the garage and as they’d been dealing with the electrics on the car, you’d think they would have investigated the fault or at least advised me of it. They assured me it’s not a fuse ‘cause according to them, the indicators and the hazard warning lights are on the same fuse and the hazards are working. So they decided it’s almost certainly the stalk switch and booked it back in for tomorrow so that they could strip it all down. Well the indicators and the hazards are on separate fuses and it was in fact only a blown fuse which I replaced. I wonder how that got into the fuse box between me pulling into the garage and them test driving it, very odd indeed!  My guess is that it would have been the dearest fuse ever. My car would probably have sat against the garage wall and I’d have got charged 1 to 2 hours labour for a repair of a fault that never existed.   They also tell me that really the whole wiring loom needs replacing and they think it’s about 3 hours work (yep they can dream).

So is the idle problem a result of a shoddy wiring repair job? Did the electrical fire and the fact that the starter motor and other circuits were going crazy, send high voltages through components causing damage? Could it be that the electrical side of the idle control valve has become faulty? Is it a faulty MAF ? With the computer showing no faults (according to a crap garage) any suggestions where to start looking of would you suggest an auto electrician?

Any advice would be much appreciated.

Title: Re: Engine Idle problems
Post by tootman318 on Feb 10th, 2010, 6:56pm
Did they charge you for this super service? A scorpio with poorly electrics is beyond most average garages!!

Title: Re: Engine Idle problems
Post by st.eve on Feb 10th, 2010, 8:04pm
Hi Tootman318,

Yep for the initial repair £38 which I wouldn't have minded if not for the ensuing fire and other problems

Title: Re: Engine Idle problems
Post by tootman318 on Feb 10th, 2010, 8:12pm
Think you need a chat and a refund!!!

Title: Re: Engine Idle problems
Post by st.eve on Feb 10th, 2010, 8:16pm
Well first I need to find what the problem is as if it's as a result of their poor workmanship

Title: Re: Engine Idle problems
Post by gozz on Feb 10th, 2010, 8:21pm
st.eve.
Sounds a nightmare  :o the 12v has no MAF meter,but a common source of cutting out at traffic lights and road junctions is a tired throttle potentiometer,the little black plastic thing on the front end of the accelerator shaft near the idle air control valve,with a plug and two screws holding it on.These things are a nuisance,and I have lashed out several fifty quids to Henry for replacements for my funeral vehicles.Best borrow one to try,or find someone to test it,preferably not yer' repair 'man,it only takes ten minutes to change it.The more modern OBD2 scanners which most garages have are compatible with later EEC5 ECUs,but will not work on the older EEC4 system that the 12v uses,both systems use the 16 pin diagnostic socket,but there are only four wires in the EEC4,and a STAR type tester is required.
                             GOZZ.
                                         GOZZ.

Title: Re: Engine Idle problems
Post by PJDavis on Feb 10th, 2010, 10:49pm
I would find it hard to trust ANY garage to these cars.  I have a friendly garage that has diagnostic equipment, and another that does tough but fair MOT's.   I'm an Engineer by profession and I lecture the subject so can do simple car repairs but mainly of old cars.   I would suspect that a good deal of the wiring in the first instance has become aged and hard & crispy like my under-bonnet wiring-loom did.   Wiring diagrams, and following wires can be difficult, but once you know what wires are 'fiddled' then sorting them is a piece o pish, just like welding!   Don't trust any garage, and watch them whilst they work!

Title: Re: Engine Idle problems
Post by st.eve on Feb 11th, 2010, 12:52am
Well does anyone have a view if the short circuit and the loom catching fire could have damaged other components that would cause the engine idel problem. My guess is that it's very probable.

Title: Re: Engine Idle problems
Post by big_timer on Feb 12th, 2010, 3:17am
the only guys that REALLY know anything about these cars are the men on this web-site.ive gained so much knowledge,and theyve give me great advice and sorted many problems for other people.a truly wonderful bunch of lads.

Title: Re: Engine Idle problems
Post by st.eve on Feb 26th, 2010, 3:52pm
Just to draw a line under this chapter and if this is of help to anyone else, the problem turned out to be the idle control valve. I got one out of a breakers, changed them over, problem solved.

It was the electrical side of the valve that was faulty so I suspect it was caused by the short circuit caused by a certain garage's shoddy work. I also noticed that the wiring to the brake fluid reservoir had been disconnected. I guess they were hoping for some additional work when I eventually noticed the warning light wasn't working or worse still ran out of fluid and crashed the car. I know one garage I'll be avoiding like the plague in future.

Perhaps a name and shame section on this site might be a worthwhile addition for all the cowboy garages out there but then again, I guess the list would be exhaustive and wouldn’t leave much choice after that.  :D

Thanks guys for all your advice.

Title: traction control
Post by baker on Feb 28th, 2010, 8:06am
hi can anyone help me ive had my car now for over4yrs cant get the traction control to work i press the button under the handbrake but nothing happerns n no light on the dash board

Title: Re: Engine Idle problems
Post by st.eve on Feb 28th, 2010, 6:40pm
Hi Baker,

You'll get a better response if you start a new post.... good luck



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