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Topic: Misfiring on low revs (Read 1731 times) |
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smitheagle
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Misfiring on low revs
« on: Apr 16th, 2007, 11:56am » |
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Got the RAC man to come and have a look at the car as it all of a sudden started vibrating and was not picking up speed like it should.
This is what he wrote on the report...
MISS FIRE ON LOW REVS
LOW COMPRESSION ON No 4 CYLINDER
He said to take to a garage for further checks.
Hows it looking for me? Is this major, expensive to fix etc.
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pete from Hull
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Non Scorpio at the moment, but still interested...
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Re: Misfiring on low revs
« Reply #1 on: Apr 16th, 2007, 12:01pm » |
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Cylinder head gasket, or loose plug?
the later is the cheaper
hth
Pete
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smitheagle
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Re: Misfiring on low revs
« Reply #2 on: Apr 16th, 2007, 1:01pm » |
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He checked the plugs and said they were fine 
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Spannerdemon
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Re: Misfiring on low revs
« Reply #3 on: Apr 16th, 2007, 1:12pm » |
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Did the RAC guy check the LEAD to No 4 cylinder?
Also check inside the Distributor Cap. Often overlooked, the posts can get so badly oxidysed that they fail to carry current. Chip away any crud that's on them, and try another lead.
Failure of one cylinder 'suddenly' would be strange. Usually they go over a period with loss of water, bad compression, poor performance etc leading up to it. It can happen, but my money's on an electrical fault. 
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smitheagle
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Remember, I know NOTHING about cars
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Re: Misfiring on low revs
« Reply #4 on: Apr 16th, 2007, 3:09pm » |
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It literally just happened with no warning. I drove to work in the morning, fine, then got in after work, and as soon as i started it up, it was vibrating/shaking. Then when i did start driving it did not want to accelerate as quickly as it did, and it fails to pick up speed like it should.
He cleaned up the spark plugs and it made no difference. He then put a compressor thing in it with a dial on it.
I have no idea about cars, but will take a look through the online manual thing and check the above.
Cheers
Dean
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Jonnycab
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Former owner of 2.3 Ultima Facelift saloon
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Re: Misfiring on low revs
« Reply #5 on: Apr 16th, 2007, 3:45pm » |
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What engine is it ?....If it's the 2.0 or 2.3, then I would suspect the coil pack on number four plug has failed 
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scorpio_man
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Ford Kuga awd
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Re: Misfiring on low revs
« Reply #6 on: Apr 16th, 2007, 3:46pm » |
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hi there
could be the coil pack. or the wiring to it.
that's where i'd be looking first.
hth
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Spannerdemon
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Re: Misfiring on low revs
« Reply #7 on: Apr 16th, 2007, 4:27pm » |
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Quote:| He then put a compressor thing in it with a dial on it |
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That would probably have been a compression tester which is a tool used to measure the compression within each cylinder. All cylinders should read a fairly similar amount when the engine is new, but in an older engine some variation is almost inevitable, so I wouldn't worry too much.
I go with the others on this. Electrical fault, and probably easily found and sorted out.
Remember that most garages don't have much idea about these cars, so don't get conned. By carefully checking under the bonnet, you will probably be able to diagnose this yourself, with our help and the help here on the website.
There's a lot of satisfaction in doing your own work, and not simply saying you 'don't know about cars'! 
Maybe someone in the London area has a spare working coil pack, or is breaking a car with one?
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TiberiuS
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Ex. 1996 2.3 Ultima - RIP P789 KHJ
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Re: Misfiring on low revs
« Reply #8 on: Apr 16th, 2007, 6:03pm » |
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Hi. Sounds to me that maybe the coilpack or HT lead to no4 failed giving it the rough running and lack of power, lack of spark in that cylinder has flooded it with fuel, washing the oil away and causing the low compression. At least that's what I'd be thinking if it was my car.
Good luck.
Regards, Bruce .
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Bruce - '07 Jaguar XKR coupe, '95 Jaguar XJ Sport 4.0, '82 Ford Capri 2.0 Ghia, '15 Honda Civic (sloooooww..)
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Jonnycab
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Former owner of 2.3 Ultima Facelift saloon
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Re: Misfiring on low revs
« Reply #9 on: Apr 17th, 2007, 12:36am » |
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After that many suggestions about a faulty coil pack, then it's gotta be worth a try
Hope you get it sorted
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RichardMS
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More mods coming soon !
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Re: Misfiring on low revs
« Reply #10 on: Apr 17th, 2007, 8:23am » |
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If it is the coil then why has he got low compression on cyl 4, Sounds like the head/gasket could be on it's way out as well 
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Jonnycab
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Former owner of 2.3 Ultima Facelift saloon
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Re: Misfiring on low revs
« Reply #11 on: Apr 17th, 2007, 9:45am » |
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It depends on how much lower the compression is in that cylinder than the others. As Spanners stated...a variation in older cars is not uncommon.
Would a dodgy head gasket suddenly cause the car to vibrate & shake ?...surely there would be clues leading up to the event, like coolant loss/oil in coolant ....whereas, coil packs can & do suddenly fail
Also, it's a possibility that the RAC guy was just guessing, like we all are
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Spannerdemon
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Re: Misfiring on low revs
« Reply #12 on: Apr 17th, 2007, 11:23am » |
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It Could be a bad exhaust valve on that cylinder, but happening suddenly makes it strange.
A variation of 10% from cylinder to cylinder on older engines is common, and generally won't cause too much of a problem. As a rule, most engines should have 140 to 160 lbs psi of cranking compression with no more than 10% difference between any of the cylinders.
I wonder if the breakdown guy took out ALL of the plugs and left the throttle fully open, before checking each cylinder in turn, because if he didn't then the readings will not be accurate. Checking with an adjacent plug still in place (if there's a problem between two cylinders for example), will not give proper readings on the cylinder being tested.
Still going electrical on this one for me.
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smitheagle
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Re: Misfiring on low revs
« Reply #13 on: Apr 17th, 2007, 11:24am » |
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wtf is a coil pack 
I would love to be able to do it myself (im skint, so the cheaper the better)
Can anyone recommend a local garage (Lewisham/Bromley) that have maybe worked on your Scorpio, that i can take it too with some of these ideas? Or even one of you lovely (local) Scorpio owners have an idea of what to do/check/etc?
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smitheagle
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Posts: 59
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Re: Misfiring on low revs
« Reply #14 on: Apr 17th, 2007, 11:25am » |
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He took out the top one, and swapped with the one next to it. He also brushed it with a wire brush (thats what it looked like)
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TiberiuS
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Ex. 1996 2.3 Ultima - RIP P789 KHJ
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Re: Misfiring on low revs
« Reply #15 on: Apr 17th, 2007, 11:57am » |
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Coilpacks are easy to replace...just unscrew them, unplug the loom and put the new one in...but not cheap to buy new so try and get hold of one second hand, even just as a temporary fix.
What engine is it? The 16v only has 2 packs so if one went you'd most likely lose spark on 2 cylinders.
Regards, Bruce.
P.S: The coilpack is the thing which sends the spark to the sparkplugs, if it dies then you get no spark... Not sure about the V6 but on the 16v they're under the dark grey cover with the Ford logo on, on top of the engine...you need to remove them to replace the sparkplugs so they're easy to get at.
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Bruce - '07 Jaguar XKR coupe, '95 Jaguar XJ Sport 4.0, '82 Ford Capri 2.0 Ghia, '15 Honda Civic (sloooooww..)
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smitheagle
Junior Member
Remember, I know NOTHING about cars
Posts: 59
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Re: Misfiring on low revs
« Reply #16 on: Apr 17th, 2007, 12:00pm » |
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Its an 8v.
Is there a picture of the coil pack in the online manual? or can someone tell me what it looks like and where i would find it?
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Jonnycab
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Former owner of 2.3 Ultima Facelift saloon
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Re: Misfiring on low revs
« Reply #17 on: Apr 17th, 2007, 12:17pm » |
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Does this help.....
http://www.fordscorpio.co.uk/DOHC2L8Vmanual.htm
Under 'description' it shows that the coils are item number 1, & shows them at the front of the engine ?
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smitheagle
Junior Member
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Posts: 59
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Re: Misfiring on low revs
« Reply #18 on: Apr 17th, 2007, 8:02pm » |
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Ok, update. I unplugged leads that were going into thing at front of engine and into the spark plugs and then plugged them back in (basically i fiddled with them) and then took it for a quick drive around the block and it did seem better. Not struggling at the low revs, although it did seem to still slightly struggle to pick up speed.
Ill report back tomorrow after i drive to work (a proper test)
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Pegasus
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24V Cosworth Ultima Born: Sept 97, sold Aug 23
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Re: Misfiring on low revs
« Reply #19 on: Apr 18th, 2007, 12:40pm » |
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on Apr 17th, 2007, 11:24am, smitheagle wrote:
Can anyone recommend a local garage (Lewisham/Bromley) that have maybe worked on your Scorpio, that i can take it too with some of these ideas? Or even one of you lovely (local) Scorpio owners have an idea of what to do/check/etc? |
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When I want something done on mine that I can't do I take it to:
Hartfield Motors, near Eden Park station on Upper Elmers End Road, Beckenham. They always do an excellent job and wont B*ll**it you (and very reasonable). Call 020 8658 9623. Peter's the guvnor and Tony his mate - both knowlegable guy's.
Been using them for about 3 years.
Paul
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