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Topic: Misfire under load (Read 1091 times) |
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Paulus
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Big and Ugly....DON'T MESS!!!
Posts: 150
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Misfire under load
« on: Jan 23rd, 2006, 9:09am » |
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12V Ultima Estate.
Why does my car misfire when under load? It's fine when cruising, but when I put my foot down, oh dear.
Paul.
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Dave
Senior Member
Tourmallard 24v (ex-owner)
Posts: 1984
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Re: Misfire under load
« Reply #1 on: Jan 23rd, 2006, 9:56am » |
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Check spark plugs, ignition leads, distributor cap and rotor arm for starters. Might find they just need a clean up!
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David_South_West
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24V............ .Goodness
Posts: 188
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Re: Misfire under load
« Reply #2 on: Jan 23rd, 2006, 10:33am » |
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Had same problem with 24v ..new set of plugs sorted out problem.
Good luck
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Paulus
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Re: Misfire under load
« Reply #3 on: Jan 23rd, 2006, 12:31pm » |
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Well, it got new plugs at the weekend - still no better.
After a run, I did notice that the two spark plugs furthest away rom the front of the car had got oily, the rest were fine. Could that be relevant?
Paul.
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Dave
Senior Member
Tourmallard 24v (ex-owner)
Posts: 1984
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Re: Misfire under load
« Reply #4 on: Jan 23rd, 2006, 1:40pm » |
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Could be, sounds like they got oily quite quick. How are your cam cover gaskets looking? Mine leak a bit and that gets down the spark plug holes.
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David_South_West
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24V............ .Goodness
Posts: 188
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Re: Misfire under load
« Reply #5 on: Jan 23rd, 2006, 2:41pm » |
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Could be plug leads...trying checking under bonnet when it's dark....any shorts are easier to see.
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Paulus
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Big and Ugly....DON'T MESS!!!
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Re: Misfire under load
« Reply #6 on: Jan 27th, 2006, 11:33pm » |
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No shorts (from what I could see). I went to Halfords to get some new leads anyway, but the don't have them listed in their book. 
I'm off to my local Ford spares department in Stafford tomorrow. 
The misfire is getting worse. Any other suggestions? 
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Paulus
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Re: Misfire under load
« Reply #7 on: Jan 29th, 2006, 2:40pm » |
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Right then.
New leads fitted (and air filter). There is a definite improvement, but still there is something going on under full throttle.
No leaks from the rocker to contaminate the plugs/leads. Sparkies look a little sooty.
Any more suggestions? I've got to commute 165 miles to work on Tuesday. I would rather do it without this problem.
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Dave
Senior Member
Tourmallard 24v (ex-owner)
Posts: 1984
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Re: Misfire under load
« Reply #8 on: Jan 29th, 2006, 3:04pm » |
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Have a look at the distributor cap and rotor arm, they may well be in need of a good clean!
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Paulus
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Re: Misfire under load
« Reply #9 on: Jan 29th, 2006, 3:09pm » |
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Rotor arm and distributor are all nice, clean and in good condition. I might replace them anyway. Ya never know
I have just checked the sparkies again (first time since the new leads) and they are all looking great.
So then. Next job is to try a new rotor arm and cap.
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howiedintheplace
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Based near Evesham
Posts: 1194
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Re: Misfire under load
« Reply #10 on: Jan 29th, 2006, 5:50pm » |
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Check the timing sometimes it's out a bit & can cause a misfire under load also a cracked distrubter cap or worn rotor will do the same.
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Dave
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Paulus
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Big and Ugly....DON'T MESS!!!
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Re: Misfire under load
« Reply #11 on: Jan 30th, 2006, 6:17pm » |
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I wasn't aware that the timing could be adjusted. Can it?
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howiedintheplace
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Based near Evesham
Posts: 1194
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Re: Misfire under load
« Reply #12 on: Jan 30th, 2006, 7:40pm » |
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Yeah it can, if someone has messed with the engine then it's usally out espically if they don't know what they are doing.
You should do it in service mode or unplug the throttle sensor 
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Dave
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martin_rowe
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I love YaBB 1G - SP1!
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Re: Misfire under load
« Reply #13 on: Jan 31st, 2006, 8:39am » |
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'oily quite quick' perhaps you should start with basics, carry out a conpression / cylinder loss test.
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Paulus
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Big and Ugly....DON'T MESS!!!
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Re: Misfire under load
« Reply #14 on: Feb 5th, 2006, 5:00pm » |
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Another update.
No more oily plugs. They are looking good.
I have replaced plugs, leads, rotor arm, distributor cap and air filter.
I have taken a look at the injectors - nice and clean.
I can't find any cracked hoses that would give an induction/vacuum leak somewhere.
Compression tester on order.
How do I go about checking the timing? I don't think that it is the problem because the the car has been OK up until the last few weeks.
Also, the tacho dances a merry dance when it is misfiring. Coil perhaps?
If I had any hair to pull out, I'd be doing that!!!
What else could it be?
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ricky
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Re: Misfire under load
« Reply #15 on: Feb 5th, 2006, 7:20pm » |
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missfire under load is nearly allways caused by the electrical system , ie plugs ,leads, coil, wiring, ect
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Paulus
Full Member
Big and Ugly....DON'T MESS!!!
Posts: 150
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Re: Misfire under load
« Reply #16 on: Feb 7th, 2006, 11:20am » |
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Right then. My Compression tester has arrived. What should I be getting. I know that they should all be within about 10psi or so, but in what range?
Also, can anyone point me in the right direction for checking the timing?
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ferretmobile
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2.3 saloon S reg & all the toys. mmmm toys
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Re: Misfire under load
« Reply #17 on: Feb 7th, 2006, 6:05pm » |
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I have got this problem as well 
Just as you say, under load or on kick down. I had 4rds put in two new ignition coils and since then ...hmmmm
Ferret
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howiedintheplace
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Based near Evesham
Posts: 1194
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Re: Misfire under load
« Reply #18 on: Feb 7th, 2006, 6:17pm » |
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Well it don't sound like the timing has been afected but you can check it with a strobe conected to plug one & the TPS disconected to put it in service mode.
I think it's 15 degree @ tick over for a CAT 12V but do check that.
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Dave
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ferretmobile
Full Member
2.3 saloon S reg & all the toys. mmmm toys
Posts: 343
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Re: Misfire under load
« Reply #19 on: Feb 10th, 2006, 2:01pm » |
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I have now bunged in some STP fuel treatment and the problem isnt so bad but when the engine is cold it misfires if I floor it. Most of my daily driving is on motorway and when the engine is nice and warm the problem seems to go away...hmmm
Maybe a case of scorpiosis
But I am suspecting a dodgy plug at the mo, I diddnt have this problem untill recently, FORDSput in two new ignition coils cos one failed on me, spose at 86,000 they have reached the end of their life and to replace both makes sense. BUT, a day or two after I got the car back,
this misfire thing started. wether it is due to a better source of ignition finding a weak spot in the system is open to conjecture. I dont think it is timing because it ticks over and drives fine..... most of the time LOL
any comments or help would be most apreciated.
I have had an RAC man look at it and he reckons it is a fuel problem but I am not so sure.
Oh yeh, and the front discs have gone wobbly...............................AGAIN!!! I am on the third set since having the scorp. This in only three years and I dont use the brakes hard or sit on them in traffic. what were 4rds thinking when they designed the 2.3 with unventilated discs or was it a friday evening..."oi nobby, wotcha dooin...its nokin orf tym!! or some such conversation 
errr rant over...Ferret
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