My Supra recently decided it did not like idling. It started with classic flucuating rpm at idle, up and down. Unplugging ISC had no change. It seemed to run fine once you opened the throttle a little, either to make idle a little higher or to drive down the road. So I started checking things- I measured resistance through ISC as outlined in tsrm, and it was a littlle too high. So I picked up two junk yard units that measured right in middle of acceptable range- 20ohms. Before I put one on I completely disassembled, cleaned and lubed. It ran the same. I started checking out other things and found a few cylinders seemed to be missing at idle, but didn't seem to at higher rpms. Distributor cap and rotor looked a little chewed up, so I replaced 'em, along with O2 sensor, which I just knew was very old, possibly original from '87. It made it idle better, but ISC is still doing nothing.
As I understand it receives constant power on middle two terminals and ecu provides grounds to move it in and out. It has power on plug, but I don't see it switching ground on any of other four terminals. I tried wiggling and pinching along wire harness but no changes.
It has no codes and check engine light seems to work like it's supposed to.
Next thing I'm going to check is for continuity of wires from isc plug to plug on ecu, if that checks good then it's pointing to ECU problem?! I guess I can check for it switching grounds at ecu plug too.
So here is my question for some of you gurus- are there any other components or problems that would cause a good isc circuit to not work? If my doopleganger was jammed or the gigershmecker burnt? What if the blinker fluid resevoir was dry would that cause isc to not work? I know my muffler bearings are old. Anyway, seriously, what else should I check and look into before putting a bullet through the ECU?
It freaking St Patrick's Day! And I'm Patrick, and mostly Irish, so I'm about to go out and do some drinking, so I think I'm done checking this pile of Toyota for tonight, but please offer up any tips or info you got. Cheers!
As I understand it receives constant power on middle two terminals and ecu provides grounds to move it in and out. It has power on plug, but I don't see it switching ground on any of other four terminals. I tried wiggling and pinching along wire harness but no changes.
It has no codes and check engine light seems to work like it's supposed to.
Next thing I'm going to check is for continuity of wires from isc plug to plug on ecu, if that checks good then it's pointing to ECU problem?! I guess I can check for it switching grounds at ecu plug too.
So here is my question for some of you gurus- are there any other components or problems that would cause a good isc circuit to not work? If my doopleganger was jammed or the gigershmecker burnt? What if the blinker fluid resevoir was dry would that cause isc to not work? I know my muffler bearings are old. Anyway, seriously, what else should I check and look into before putting a bullet through the ECU?
It freaking St Patrick's Day! And I'm Patrick, and mostly Irish, so I'm about to go out and do some drinking, so I think I'm done checking this pile of Toyota for tonight, but please offer up any tips or info you got. Cheers!
