91 legacy rough idle

[hush777]

91 legacy 2.2 auto

Idle surges between 1250 and 1500.

Just got the car and trying to track down this issue.

Thought that it might be the iacv but changing that to a known good one didn't change anything.

Found the tps loose and set it according to specs, still didn't change anything.

Figured that I should pull plug wires and see which cyl.s where having issues.

#1 idle didn't change at all.

Ok change plug and wire

Still the same.

Pulled #2 and idle didn't change at all, ok must be the coil then.

Changed to a know good one and still the same.

did a compression check and the front 2 cyls are better than the back 2 but all are within range.

checked (with spray) for any air leaks on all the hoses.

Disconnect the maf and it dies, so I think it is good.

Just not sure what might be going on with the 2 front cyls.

 

Anything else I should check.

And  are the computers for a 93 with a manual and the 91 with the auto the same? or at least enough that I could hook up the one from my car (the 93) and see if that changes anything.

 

Thanks

Hush

 

[hush777]

Had a chance to check things on this some more.

Changed the whole intake with throttle body and coils to one off of a 92 legacy (Different injectors and harness) using my same harness.

Still rough idle and pulling the injector wire for #1 or #2 does not change the way it idles at all.

Checked for voltage at the injectors #1 and #2 10.8 volts on both.

Checked ohms on the wiring from the injector to the connector by the battery 0 ohms on both.

Checked the ohms from the connector back to the ecu and 0 ohms on both there also.

Checked for voltage at the ecu on the wiring coming from the injectors (with engine not running ) 10.89 volts there.

Checked the ground from ecu to body and 0 ohms there.

Only getting one code but haven't had it running to long so other codes might not have set yet.

changed the wiring around on the #1 and #3 injectors and now pulling the wiring off the #1 injector causes a drop in RPM but the #3 (running off the #1 injector wiring) does not.

 

Took a look at the timing belt it seems to be right on.

 

Hooded everything back up like normal and started it...... idle surges between 1250 and 1500.

Pulled the wiring on the IAC and idle dropped down.

Disconnecting #1 or #3 injector wiring still has no effect.

Ran it up to around 2000 rpm and disconnecting and reconnecting the injector wiring has the proper effect on the rpms.

 

Any ideas?

 

Thanks

Hush