Idle surge when in gear

[CarbonCruiser]

My 1989 Fj-62 idles smooth at around 700rpm when in park or neutral. When I put it in gear the idle pulsates between 600-700. It jumps back and forth and sounds a bit rough. When I put it back into neutral it purrs like a kitten again. Any ideas what is causing this?

 

[Joe Egolf]

Vacume leak perhaps ?

 

[Pin_Head]

Faulty grounding of the idle fuel cut off solenoid by the computer? Try grounding it with a jumper wire and see if it goes away.

 

[CarbonCruiser]

Faulty grounding of the idle fuel cut off solenoid by the computer? Try grounding it with a jumper wire and see if it goes away.

Pin Head can you give me some more details on this. Is this solenoid activated when the tranny is put in gear? What is the function of the solenoid?

 

[grant5127]

Check the large rubber hoses from the throttle body to the air cleaner..... they have been known to develop tiny splits and cracks and when the trans is engaged the motor torques to the left a bit and opens the cracks allowing unmetered air to enter causing a idle roll effect or some cases just die out.....

 

[Pin_Head]

Sorry, I just noticed it is a 62 and FJ62s are EFI, so they don't have an idle solenoid.

 

[cruiser88]

Check for codes..I bet it comes up code 51

 

[NocalFJ60]

Check for codes..I bet it comes up code 51

x2 first place to start and then vacuum gauge on the manifold and watch it while someone else puts it in gear.