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Discussion Starter #1
Hi all,

My 75 T Spark runs beautifully, starts first time, idles fine and, on the whole, drives fine but it seems to of developed a very random problem. It's only happened three or four times but when just coasting on the accelerator (ie accelerating but very gently) it's lurched/'kangarooed' for no particular reason. It's really caught me out! After that it's fine. Engine is all up to temperature etc so I've no idea what it could be or what could potentially be wrong with it!

Any pointers would be appreciated.

Cheers
 

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could be a sticking throttle position switch which sticks for a second when you are off gas when you gently press the accelerator the ECU still thinks you are off throttle then over compensates.
 

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Discussion Starter #3
could be a sticking throttle position switch which sticks for a second when you are off gas when you gently press the accelerator the ECU still thinks you are off throttle then over compensates.
Interesting. Where is this located and how do I check?

I also wondered if it could be a coil failing. The fault is so random that I can't believe it's anything serious. I would say it's some sort of misfire but only really happens once in every 30-50 miles or so. Very strange!
 

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The position sensor is below the throttle flap on the in-let side. You can disconnect it and run without it for a while if the problem doesn’t appear you know it’s this. I split mine open and the contacts were rusty, cleaned them up then glued the unit back together four years later its still OK, very similar symptoms to yours.
Other possibility could be a sticking Air flow meter. Just try borrowing another one for that. If you can't get one I'll send you one to try.
to test the ignition disconnect one coil and run on single ingnition if any misfires etc get that ignition working properly then swop and disconnect the other ignition. I do this test every six months because with two ingnitions it is possible to have a fault one one and not notice until you get anouther fault on the other then you have two problems to sort!!!! The twin spark system is very reliable though.
 

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Discussion Starter #5
Thanks jtalfa. It hasn't done it for a couple of days now so maybe the magic Alfa has cured itself. Will definitely check the items you've mentioned though. It was such a random issue, that it seemed odd - almost like a a total loss of engine power for a split second!
 

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I had a random misfire that was always after a few minutes of starting but never a problem for the first 2 or 3 minutes of running. Always seemed worse in damp weather.
Long story but after about a year of this fault eventually traced to a poor connection on a multiplug that feeds the relays on the front wing just behind the battery.
The multiplug sits in the scuttle panel behind the pedal box on RHD cars. With the ignition switched on I could hear the relays clicking in & out as I fiddled with it. Cleaned the contacts up, put it back together and it's been OK for the last year.
 

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Discussion Starter #7
Yes, I'm sure it's something really stupid and simple but just a case of identifying the problem. Anyway, for now, the problem seems to of gone away!
 
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