94 Legacy idle varies at times

[tonysubaru]

On my 94 2.0l the idle will jump up to 2000 rpm for a second and them back down to 400 rpm and levels at 900. it does this on occasion and not every day. It shows no code and is driving (pardon the pun) me crazy. I have taken it to part stores and no codes. Has anybody experienced this problem? I don't want to replace a whole bunch of stuff if I don't have to. Thanks. Tony.

[EVOthis]

try cleaning the IAC valve......how many miles on the car?

[tonysubaru]

The car has 140k on it and in good shape. Where is the IAC Valve? And what does it do? Thanks for your help.

[idosubaru]

i'm not familiar with it on the early legacy but IAC's typically control the idle (Idle Air Control valve = IAC). over time they just get gummed up with black soot and don't open or close all the way. typically you can just clean them out really well and reinstall, they rarely fail completely.

 

how long has it been since it had a tune up - plugs and wires? typically you'd get a CEL with a cylinder misfire code for those, but it's still possible they need replacing. unfortunately the stock NGK plugs and Subaru OEM wires are best for the EJ22.

[tonysubaru]

Thanks Gary. I has had new wires and plugs recently. It's been doing this for months now and finally I found this site for help. I can't take it to a mechanic cause it doesn't happen all the time. I will try to clean the IAC Valve and go from there. I will tell you what I find. Thanks again. Tony.

[idosubaru]

i'd clean the IAC first, that's the most likely culprit right now.

might not be a bad time for some fuel system cleaner to - i like marvel mystery or sea foam.

 

if that doesn't do it i'd begin to wonder what kind of plugs and wires you used - the EJ engines are not forgiving of aftermarket wires. they *can* cause issues right out of the box.

 

good luck!