97 OB 140k (Head gasket @ 125K) - mild surging @ 30-40 mph; just noticeable @ cruising speeds - 65-75 mph. Could it be the TC going bad? O2 sensors are both replaced; cleaned throttle body, but not the deep cleaning via the vacuum hose. Plugs are good. IAC? TPS?

 

Thanks

I'd try cleaning the TPS...that can sometimes cause tranny searching.

not the torque converter, they either work or they dont. What happens if you drive in D3

 

 

nipper

Is it at part throttle? it could be the torque converter lockup solenoid disengaging and reengaging repeatedly.

Is it at part throttle? it could be the torque converter lockup solenoid disengaging and reengaging repeatedly.

 

Noahdl88 - Yes, part throttle is when it occurs. Driving city streets @ 30-40 is most noticeable; also @ freeway - 65-75. If the TC were engaging/disengaing wouldn't the rpms change, too? If it were the solenoid is that in the tranny?

 

Also, at idle the car shakes a bit - not like it's going to die or anything's going to shake loose. But it's definitely not a smooth idle. But the rpms change very little if @ all @ idle.

not the torque converter, they either work or they dont. What happens if you drive in D3

 

nipper

 

 

Nipper - I tried the D3 and it's still there, but not as noticeable as when the car is loafing along in OD @ 35-40 mph.

 

Also, at idle the car shakes a bit - not like it's going to die or anything's going to shake loose. But it's definitely not a smooth idle. But the rpms change very little if @ all @ idle.

I think I fixed it. It may have been a barely loose plug wire. I'd been in there the week before taking off an underdrive pulley (2MPG!), and bumped it....unless it just needed me to open the hood and say "boo!"

i'd guess ignition related. how old are the wires? best if they are Subaru OEM wires or Magnecor on any EJ series engine. any others are questionable. might want to consider replacing if they are old or this returns. if it returns check the previously loose wire for damage.