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        General >> Problems >> Misfiring on low revs
        
(Message started by: smitheagle on Apr 16^th, 2007, 11:56am)

Title: Misfiring on low revs
Post by smitheagle on Apr 16^th, 2007, 11:56am

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.

Title: Re: Misfiring on low revs
Post by petehull on Apr 16^th, 2007, 12:01pm

Cylinder head gasket, or loose plug?

the later is the cheaper

hth
Pete

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 16^th, 2007, 1:01pm

He checked the plugs and said they were fine :(

Title: Re: Misfiring on low revs
Post by Spannerdemon on Apr 16^th, 2007, 1:12pm

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. ;)

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 16^th, 2007, 3:09pm

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

Title: Re: Misfiring on low revs
Post by jonnycab on Apr 16^th, 2007, 3:45pm

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 :)

Title: Re: Misfiring on low revs
Post by scorpio_man on Apr 16^th, 2007, 3:46pm

hi there

could be the coil pack. or the wiring to it.

that's where i'd be looking first.

hth

Title: Re: Misfiring on low revs
Post by Spannerdemon on Apr 16^th, 2007, 4:27pm

Quote:

He then put a compressor thing in it with a dial on it

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'! :o

Maybe someone in the London area has a spare working coil pack, or is breaking a car with one? ;)

Title: Re: Misfiring on low revs
Post by TiberiuS on Apr 16^th, 2007, 6:03pm

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 :).

Title: Re: Misfiring on low revs
Post by jonnycab on Apr 17^th, 2007, 12:36am

After that many suggestions about a faulty coil pack, then it's gotta be worth a try ;)

Hope you get it sorted :)

Title: Re: Misfiring on low revs
Post by RichardMS on Apr 17^th, 2007, 8:23am

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 :-/

Title: Re: Misfiring on low revs
Post by jonnycab on Apr 17^th, 2007, 9:45am

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 ;)

Title: Re: Misfiring on low revs
Post by Spannerdemon on Apr 17^th, 2007, 11:23am

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. ;)

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 17^th, 2007, 11:24am

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?

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 17^th, 2007, 11:25am

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)

Title: Re: Misfiring on low revs
Post by TiberiuS on Apr 17^th, 2007, 11:57am

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.

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 17^th, 2007, 12:00pm

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?

Title: Re: Misfiring on low revs
Post by jonnycab on Apr 17^th, 2007, 12:17pm

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 ? :)

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 17^th, 2007, 8:02pm

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)

Title: Re: Misfiring on low revs
Post by Pegasus on Apr 18^th, 2007, 12:40pm

on 04/17/07 at 11:24:06, 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?

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

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 18^th, 2007, 4:28pm

Cheers Paul !

Thinking of getting a new/sh coil pack and trying that first.

Title: Re: Misfiring on low revs
Post by dogma on Apr 18^th, 2007, 10:39pm

Hi mate, only just seen your entry, just an idea, i have the 2.9 12v and it was doing exactly the same thing minus the shakes. I replaced the HT leads and plugs, also the dizzy cap as it was full of white powder and crusty stuff. It ticks over great now
jim ;D

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 19^th, 2007, 9:36am

Wheres the distribution cap? whats it look like?

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 19^th, 2007, 10:55am

Distributor Cap - Bought one on ebay. Only £7.00.

Are all HT leads the same length?

Title: Re: Misfiring on low revs
Post by Pegasus on Apr 19^th, 2007, 12:38pm

HT leads are different lengths. If you're going to replace 1 best to replace all.

If you thought it was the leads you can test with a resistance meter. Maximum resistance should be 30kOhm/metre (so if its 50cm long, max should be 15kOhm).

New leads resistance is 12-15 k Ohm/m (length 24 - 90 cm)
Current leads (after 67k) is 14-17 kOhm/m (all from Ford)

Paul

Title: Re: Misfiring on low revs
Post by dogma on Apr 20^th, 2007, 11:45pm

Hi, the Dizzy cap (well on my 2.9) is directly at the rear of the engine, should have a sort of gold tube cover around it, i replaced mine and a new rota arm, be carefull tho as some places will charge up to 10 pound per HT lead if your thinking of replacing. I picked up a full set for 22 pound from A1 auto spares, the dizzy cap and rota arm were about 15 pound from Dfp, it made the problem go but by no meens perfect, but, the car has done 120000 and is ten years old, got to keep that in mind too
jim

Title: Re: Misfiring on low revs
Post by jonnycab on Apr 21^st, 2007, 2:09am

As far as I know, the 8v 2.0 doesn't have a distributor. It's electronic ignition ;)

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 26^th, 2007, 10:28am

so wtf have i just bought :o ???

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 26^th, 2007, 10:33am

From Ebay:

This is a

DISTRIBUTOR CAP

It is a brand new replacement part for the following vehicles

Granada 1.8, 2.0 85

Scorpio 1.8, 2.0 85

Sierra/Sapphire 1.8, 2.0 84-85

Part Number : 45960

Now im confused!

Title: Re: Misfiring on low revs
Post by TiberiuS on Apr 26^th, 2007, 11:53am

You're a decade behind, the old 1.6/2.0 was the Pinto or the CVH ;)

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 26^th, 2007, 11:58am

oh poop, i see now, didnt notice that little '85' at the end ! DOH! :-[

Told you all im useless!

So, ive now got 4 spark plugs, need to get new HT leads, and re-reading the above, ignoring the distributor cap suggestion, its a coil pack i need?

Wheres the cheapest place to get it?

Title: Re: Misfiring on low revs
Post by julie_quaife on Apr 26^th, 2007, 12:19pm

hi, take pegasus' advice on the garage, especially if they have experience of scorpio's, nothing better than an experienced mechanic on these baby's. other than that there is bristol st (hubby's ex-co) or ballam's at west wicham (where my baby came from). as for the symptoms, mine was driving fine slightly down on exceleration, one morning popped into mcdonalds drivethru and when i pulled away the car was shaking badly, felt lumpy and backfired a couple of times, i pulled up and gave it a couple of big revs wondering if there was a bit of s**t going through the system as i had just filled up after going fully low in the tank but decided it needed checking out so called in the rac, after a very long checkover, lean plugs, leads fine etc; he decided it was the front coil, i replaced this cost me £60 (can be around £1-120) at a ford garage though and everything was fine, when one coil goes it can be possible for the other one to follow (i,ve got a 2.3 16v) so if you get a good price maybe buy two just in case, good luck with it all, julie

Title: Re: Misfiring on low revs
Post by Pegasus on Apr 26^th, 2007, 12:57pm

on 04/26/07 at 12:19:56, julie_quaife wrote:

What a small world Julie - I got mine from Ballams :)

In my experience - if I had a choice of where to take my car from the 3 options it would not be Balaam (cost/convenience) and definately not Bristol St (not just cost/convenience). >:(

Paul

Title: Re: Misfiring on low revs
Post by TiberiuS on Apr 26^th, 2007, 1:51pm

Have you tried new HT leads yet? No dizzy on yours but the HT lead (lead from coilpack to sparkplug) to that cylinder could be failing, giving it the misfire. I'd try the leads then try and get hold of a known working coilpack.

Good luck :).

Title: Re: Misfiring on low revs
Post by julie_quaife on Apr 27^th, 2007, 12:15am

pegasus, it is certainly a small world!!! i wouldn't use a main dealer for general servicing and repair, not only for the reason of the cost but due to working in garages over the years have felt that many youngsters nowadays are trained to be fitters and not mechanics although this is mainly due to high hourly rates making it more feasible to replace instead of repairing. everything is so computer orientated now as well

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 29^th, 2007, 10:34pm

Ive enquired to Ford Parts UK for a coil pack and HT leads.

Another thing ive noticed recently is that along with the slight shake/vibrate i get with the car, if i turn on my air con, the car shakes/vibrates a lot more, until i turn it off again. I only notice it if im stationery.

Its also getting slightly worse picking up speed, im needing to go up hills in 1st if i want to get somewhere!

Title: Re: Misfiring on low revs
Post by smitheagle on Apr 29^th, 2007, 10:38pm

Should i add the above problems to a different thread?

Title: Re: Misfiring on low revs
Post by jonnycab on Apr 29^th, 2007, 11:40pm

Air-con compressor ain't getting a bit stiff is it ?

Title: Re: Misfiring on low revs
Post by smitheagle on May 30^th, 2007, 12:52pm

FIXED!!!

Thanks for all your help! I bought some spark plugs about a month ago (as mentioned above), couldnt afford to get the other bits just yet. I got a mate to put the spark plugs in yesterday and **** me! it sorted out everything, the mis firing, slow acceleration, vibration etc! Spark plug 4 had black crap all over it. All this trouble fixed for £20!

Very happy, now i will sort out alloys and sound system!

Title: Re: Misfiring on low revs
Post by Grumpyg1t on May 31^st, 2007, 9:11pm

I had an Escort once where i was pulling my hair out with a misfire which turned out to be the plugs, I'm glad you got it sorted.