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Topic: Engine Running Bad (Read 5785 times) |
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don
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Engine Running Bad
« on: Feb 15th, 2012, 2:32am » |
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Hi i have just found this site and i am after some advice,I have a 1995 scorpio estate ultima and it sounds like it is running on 3 cylinders and stinks of unburnt fuel, It is a 2.0 litre dohc engine up till now it has run perfect, i have had it into the garage and they said that the wiring loom is duff it is all hard and britle and they want £350 to fix it,is this a good price,ANY IDEAS. I need to get it fixed as soon as possible as my wife is disabled and we need it to get about,i have a little bit of car know how,so is it something i could do myself and what would be the cost.
many thanks.
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Kenboy
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Re: Engine Running Bad
« Reply #1 on: Feb 15th, 2012, 6:15am » |
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Hi Sorry about this but I am afraid you will have to bite the bullet on this one, the price is about right, some members have managed to repair old looms but generally this can only be considered a stop gap method, and you have to know what you are doing, this is a common fault with these cars.
Kenboy
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gozz
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Been around awhile
Posts: 3475
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Re: Engine Running Bad
« Reply #3 on: Feb 15th, 2012, 10:15am » |
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don.
If you exercise patience and determination it is not technical to repair the engine loom.The faults are brought about by the insulation breaking down due to heat and age,this causes short circuiting.The worst deterioration is under the spark plug cover and down to the temp sensors and throttle potentiometer via the injector connector casing.The loom is easily removed from all the foregoing,but the wires going to the crank sensor and oil pressure switch are best left out of the repair as they are a sod to get at.The part from the injector box to the big connector is not usually affected so badly.Take off the plug cover and the top of the injector box,remove the connections from cam sensor,ignition coils,injectors,temp sensors and throttle pot.Strip off outer casings and bin them,inspect individual wire for disintegrating insulation.It is very unlikely that any wire will be broken,if you do find one,solder it up.Obtain a big roll of proper electricians insulating tape,not Mickey Mouse DIY crap.Tape every damaged wire individually then tape them together into a loom.If you liked, some self adhesive heat resistant aluminium tape could be used,but the job you do will outlast your time with the car anyway.
There are dozens of posts on here,some current relating to these problems,most people throw their hands in the air and many have scrapped their cars because of wiring problems which is the biggest bugbear of these otherwise excellent steeds.
I have just retired from the funeral carriage trade,and ran many Scorpios AND repaired several engine looms to good effect.
Take a stiff Scotch and wade gently in,you CAN do it.
All the best GOZZ.
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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: Engine Running Bad
« Reply #4 on: Feb 15th, 2012, 12:10pm » |
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De ja vu #2! 
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Mike H
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Tompion
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1997 2.3 Ultima estate.
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Re: Engine Running Bad
« Reply #5 on: Feb 17th, 2012, 8:49pm » |
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on Feb 15th, 2012, 2:32am, don wrote: it sounds like it is running on 3 cylinders and stinks of unburnt fuel,
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If it is actually running on 3 (rather than just sounding like it) it’s unlikely to be the loom.
Faulty coil-pack, plug or plug lead would be more likely.
This is because it uses a wasted spark system (each coil-pack fires a pair of plugs on inlet & exhaust strokes) so if it were the loom to run on 3 it would have to drop power to 1 coil-pack on alternate strokes.
The unburnt fuel would lean towards this (assuming it is running on 3), although I suppose a problem with the injectors or their wiring may cause it.
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ABS multiplug wheel sensor pins MK IV or MK 20
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Mike H
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Renault Clio
Posts: 2594
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Re: Engine Running Bad
« Reply #6 on: Feb 19th, 2012, 12:19pm » |
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on Feb 17th, 2012, 8:49pm, Tompion wrote:so if it were the loom to run on 3 it would have to drop power to 1 coil-pack on alternate strokes.
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Not terribly likely? What he means is, suppose if one coil primary wire broke for example, TWO cylinders won't fire.
So seems to point more toward secondary side, HT lead / cap short / bad plug etc.
Or could be an injector not opening
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Mike H
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don
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Re: Engine Running Bad
« Reply #7 on: Feb 21st, 2012, 9:14pm » |
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I have put on a brand new fuel cut off loom from ford the car is not misfireing but the car is running very rich ,stinks of unburnt fuel, as if the choke is on all the time.
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leewar
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Re: Engine Running Bad
« Reply #8 on: Feb 22nd, 2012, 1:23am » |
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Don, As Tompion say's, coil pack/s could be your problem.
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don
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Re: Engine Running Bad
« Reply #9 on: Feb 22nd, 2012, 2:11am » |
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HI i have had all 4 plugs out and they were all black and sooty,there was no sign of anything bad with the coil packs,is there anyway of testing them they both looked ok
many thanks.
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Jonnycab
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Former owner of 2.3 Ultima Facelift saloon
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Re: Engine Running Bad
« Reply #10 on: Feb 22nd, 2012, 2:38am » |
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Other causes of heavy choke could be a blocked air filter, a faulty engine coolant temperature sensor (not the gauge sender, the one next to it).......Or maybe it just needs some new plugs 
Best to get the obvious out of the way before thinking of the serious causes like the engine loom 
Just because the top of the engine wiring loom is brittle, it doesn't mean it will run bad because of this. Exposed (even old insulated) copper wire will suffer oxidation, meaning its conductive properties will be reduced....but a signal will still transfer if the integrity of the wire is intact & it has no shorting.
If you suspect the loom, then I would take a good look at the part of it where in goes to the inlet manifold sensors & down below the inlet manifold to the crankshaft sensor. This part of the loom can look even crispier & stripped of insulation more than the top part of the loom, with the chance of many more exposed wires touching/shorting against each other
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Tompion
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1997 2.3 Ultima estate.
Posts: 2918
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Re: Engine Running Bad
« Reply #11 on: Feb 22nd, 2012, 12:02pm » |
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There’s a vacuum hose from the manifold to the fuel pressure regulator, if the diaphragm in the regulator splits it can let petrol into the manifold. Pull the thin pipe off the regulator and put your thumb over the hose to keep the engine running – check there is no petrol coming out of the regulator.
On this picture the FPR is immediately above the arrow furthest to the left & the vacuum hose is the thin one at the back of the FPR heading downwards from just under the tail of the arrow.
You can drive with the hose plugged to see if it improves the running (its function is to drop pressure a little at tickover/overrun).
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don
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Re: Engine Running Bad
« Reply #12 on: Feb 23rd, 2012, 11:55pm » |
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Hi again i have done what you said and it is still running bad it is hunting on tickover the revs keep going up and down if you know what i mean i can still drive the car but it is still is as if it has the choke full on all the time and you can smell it that it is running to rich all of the time,like you have put the choke on full and not took it off,as said before new plugs new wiring loom ciols look good no sign of any cracks at all look like new,all other wires under bonnet all been checked no sign of been brittle.
many thanks
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Mike H
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Renault Clio
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Re: Engine Running Bad
« Reply #13 on: Feb 24th, 2012, 1:58pm » |
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Probably got to the point where it needs an OBD read, summat not right somewhere, as though the computer thinks it's getting loads of air, but it isn't.
Also gobs of neat petrol down the exhaust will kn@cker the catalytic converter as well
When it was working fine then went wrong, was it suddenly and went rich like this, or did something else happen before that?
Was anything else done to it while it was in the garage?
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Mike H
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szinyei
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Re: Engine Running Bad
« Reply #15 on: Sep 4th, 2019, 6:58am » |
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I had the same problem. It can be a vacuum problem. Maybe a tube came off, became brittle. Or the AGR is not vacuum-tight. In a garage it has been tested with alcohol sprayed over the engine. As soon as the proper untight, i.e. leaky place was found and the engine was sucking in alcohol instead of air (through the vacuum) it was then just fine...
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