M20 hunting idle shock!

[alan1272]

i know this is a common fault and i have been scouring all the other treads on it all day but to no avail so please excuse me for starting another

i have an early 320i m20b20 and the idle is hunting between 750 and 1000rpm when fully warm. the other threads i checked suggested several possible faults which i went through

TPS: checked with a multimeter according to the instructions in haynes, it clicks and has the resistance that haynes describes

air/vaccum leaks: went over the pipes and found nothing

ISV: on this one haynes wasn't very helpfull and i searched for ages before i found what i assume is it down by the starter



tested it on a battery and it clicks when current is applied. reconnected it and started the car, then used two "jump" wires to the battery to operate it manually. when current was applied the car idles at a steady 1200rpm.

another thread mentions a connector plug under the inlet manifold where the terminals corrode but i can't for the life of me find it

this has pickled my head and im unsure what to do next, any help will be greatly appreciated

[michael24m]

is yours a L-jetronic?
my m20b20 was doing that until i adjusted the aditional air slide valve it, has a screw with a head for a broad flat screwdriver, just tweak it.(motronic ones have ICVs), after it stabilises you can further adjust the idle from a screw at the accelerator assembly. also the timing afects the idle.

[DaveD]

something on here might help

http://www.verrill.com/car/idle/e30_idleproblem.shtml

but there was a very long thread a month or two ago which came to the conclusion that if all else fails get a new (or newer) FPR..