prox71 Posted August 27, 2018 Share Posted August 27, 2018 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? Quote Link to comment Share on other sites More sharing options...
kevscab Posted August 30, 2018 Share Posted August 30, 2018 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. Quote Link to comment Share on other sites More sharing options...
prox71 Posted August 30, 2018 Author Share Posted August 30, 2018 thanks Quote Link to comment Share on other sites More sharing options...
Paul Grainger Posted September 1, 2018 Share Posted September 1, 2018 (edited) Check the base idle setting and fuel mixture. These were renowned for drivability issues. Is the idle speed control valve on the bulkhead or on the inlet manifold? Edited September 1, 2018 by Paul Grainger Quote Link to comment Share on other sites More sharing options...
prox71 Posted September 1, 2018 Author Share Posted September 1, 2018 some time ago when I tried looking for the idle speed control valve, but believe there isn't one? theres a potentiometer, but have replaced this Quote Link to comment Share on other sites More sharing options...
Paul Grainger Posted September 2, 2018 Share Posted September 2, 2018 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 Quote Link to comment Share on other sites More sharing options...
prox71 Posted September 2, 2018 Author Share Posted September 2, 2018 yes potentiometer is on inner wing located iscv it is on the back of the drivers side suspension turret Quote Link to comment Share on other sites More sharing options...
Paul Grainger Posted September 2, 2018 Share Posted September 2, 2018 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 Quote Link to comment Share on other sites More sharing options...
prox71 Posted September 2, 2018 Author Share Posted September 2, 2018 have adjusted the base idle as suggested, doesn't seem to be any better could be the idle speed compensator sensor, is there anywhere you can get these? thanks for your help Quote Link to comment Share on other sites More sharing options...
Stephen Bearded Minky Hill Posted September 4, 2018 Share Posted September 4, 2018 had this with mine. Get rid of those NGK plugs and try BOSCH FR6DCX. Quote Link to comment Share on other sites More sharing options...
prox71 Posted September 19, 2018 Author Share Posted September 19, 2018 cheers pal, changed the plugs seems to be ok now, the plugs I took out were FR5DC, they have a gap of 0.8mm, FR6DCX have a 1.1mm gap, someone mis-described them on ebay, 4 years of jerking around has left me with the shakes though Quote Link to comment Share on other sites More sharing options...
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