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Escort Cabriolet Club

MKIV efi xr3i 'jerking'


prox71
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Car jerks a lot when trying to maintain a speed of around 20 to 30. 1.6 xr3i 86000 on the clock.

Have replaced spark plugs, oil and filter, ht leads, cambelt, fuel filter, potentiometer. 

car runs ok in fourth gear doesn't happen then.

Any ideas?

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Mine is the same lol not too jerky but enough to notice if trying a constant speed. I've changed all the things you have mentioned too. And in just about to fit a new coolant sensor for the ecu so it recognises whenit's warm etc for fueling. I'll let you know how I get on when I got it. 

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It will be there somewhere......

The very early EFIs had a Hitachi valve mounted on the air box. These were the worst and a modification came out to mount it on the baulkhead with a piece of hose running to it. Then they were modified in production to include the valve on the air intake throttle body which was a lot better.

The potentiometer you have replaced is the one on the inner wing I pressume? This is to adjust the fuel mixture which can only be done with an exhaust gas analyser. 

There is an air bypass screw on the throttle body. Try adjusting this to get the idle speed to sit at 750rpm with the idle speed control valve disconnected (Unscrew to speed up). Then reconnect the valve and adjust the potentiometer to to set the fuel mixture.

Most garages should have an exhaust gas analyser and only takes 15 mins so shouldn't cost much.

Cheers

 

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Ok. So yours is one of the early ones which has been modified.

Check the base idle as described previously. If on the inner wing by the potentiometer there are two black wires with spade connectors then join them together. This will make the cooling fan run constantly while you adjust base idle

Cheers

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  • 3 weeks later...

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