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Old 18-10-2007   #1
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Newbie with accelerator judder/stutter

Hi, I am new here and the proud owner of 2 Multiplas (1 is the wifes) and a 110 Land Rover.

They are both Petrol 100SX's and think both year 2000 'ish. We love them - funnily enough.

I have an issue on one where when hovering on the accelerator at around 40 or under loaded acceleration (i.e. in too high a gear) at around the same speed, the engine stutters quite dramatically. Seems like it is missing, but if I dip the clutch and rev it and drop a gear, so increasing the revs, it is OK.

Also, compared to the other which is pretty spritely, this one seems a bit sluggish overall.

Wondered if you guys have any idea. Thoughts I have had are throttle potentiometer (if there is one?) or AFM, or ignition. Bit tricky to work on these as I haven't managed to find a workshop manual yet. I am a competent mechanic (you have to be with a Land Rover!) but have to date used Middleton Fiat because they are so good and I have had the LR as a project! Having now finished that, I thought I would start learning about the Multiplas.
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Old 19-10-2007   #2
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Re: Newbie with accelerator judder/stutter

I don't know how specific this would be to Multiplas but in general, mis-firing when a petrol engine is labouring is caused by a weak spark; the high pressure vapour in the cylinder has too high an electrical resistance for the spark to jump the spark gap. Is this likely? Have you checked the plugs? If the plugs are ok it might be worth having the HT system checked; this kind of problem was common enough on old ignition systems where the HT voltage dropped with low engine revs, but it is unusual on modern engines with solid state ignition systems. Good luck; it's stories like yours that makes me glad I've got an oil burner
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Old 19-10-2007   #3
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Re: Newbie with accelerator judder/stutter

Thanks Combwork, I will check the 'usual' bits this weekend. Just thought I would check to see if there were any Multipla specific 'issues' that produced these symptoms - there seem to be plenty of others!! Also being used to older cars wondered what fangled modern technology could be causing this. Is there a Throttle position sensor/potentiometer on these? If so, where?
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Old 20-10-2007   #4
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Re: Newbie with accelerator judder/stutter

[quote=Coastcard;1264254]Is there a Throttle position sensor/potentiometer on these? If so, where?[/quote]


I don't know. If the petrol Multipla's got one, logically it would be on the same shaft that the throttle cable carrier is mounted on; pulling the cable turns the carrier which opens the air intake and operates the potentiometer. A Fiat agent could check the diagnostics, but quite a few independent garages have the same Bosch diagnostics readers; if there's a local guy you know and trust, it might be worth letting him look at it.

Good Luck.
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Old 28-10-2007   #5
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Re: Newbie with accelerator judder/stutter

Yikes... just put a new battery in as the old one had given up the ghost and it won't start now. The vehicle had been left for probably 6-8 weeks without a battery or being used.

Turns over fine. Have taken a plug out and there is a spark. After cranking, the plugs aren't getting wet. There is a slight smell of petrol under the bonnet, but not from the exhaust. Oh and yes, there is half a tank of petrol in her.

Is this a single or multi point injection engine? Is it possible to fault find it without a computer?
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