Club 80-90 Forums

Hi all got one im trying to figure out, as i drive my 1990 T25 2.1 its not running smooth seems like the engine isnt getting enough of something changed air filter and plugs and all the usual then after consulting the haynes manuel i ended up checking the Throttle Valve Switch (4b.4) when the engine is idleing i should get 1.5 ohms or less across a tester but i get open circuit, the switch only closes when i push the throttle all the way open....so basically working the opposite way it says it should in the book so has anyone else had this problem and is it a case of new switch and is it that causeing it not to run smooth because i dont actually know what it controls?? If Anyone has had same issue hope you let me know cheers.

The switch should be closed (zero ohms) when the throttle is fully closed or fully open.
I cant remember how it adjusts, but it sounds like it just needs a little tweek.
T

Yeah Closed at idle according to the haynes manual, but mines the other way round open on idle and close at full throttle, it says theres an adjustment but not to do with the switch thats what im confused about. cheers though

you should get continuity at fully closed ie idle and fully open, full throttle enrichment. There are two small allen headed screws one is clamp, one has a cam on it and it is possible to adjust if required, but chances are just crud - you need to take whole throttle body off engine to check the operation of the microswitch underneath, in your hand with the cover off (if present) it will make sense, don't try and adjust insitu, you need plus gas and patience and decent tools, but as I said it probably just needs a clean up - disconnect accelator cable, keep bits safe, remove rubber hose,disconnect plug, undo nut holding plug to inlet manifold, undo two phillips head machine screws and remove throttle body from manifold

Cheers Aiden ive had another look at it and i managed to get the switch to close on both idle and full throttle but still have the same problem of it not running smoothly i now think that it has to be the fuel filter i bet it hasnt been changed in years so ill put a new one on this week and hopefully that solves it, cheers for your help with the switch.

most poor running I'm coming across is ht leads breaking down, arcing at the shield not in the cylinder, new leads seem very poor compared to originals