FoxbodyMech

So... I have an 85 5.0 AOD transmission, and recently she has gotten a little pissy i guess you could say. She often starts up at around 1000RPM when she used to idle at around 500-750RPM when the engine was cold, and now, when i drive her for between 5-20 minutes, when i put her in park or neutral, she idles between 2000 and 2250RPM. I have a suspicion that her o2 sensor is to blame, but i am not sure. I know she needs an in-depth tune-up because i have had her for almost a year now and have no clue how old her spark plugs, cap, and rotor are. Any ideas as to what could be causing my weird idle?

Jarret

Don't know if this will help at all but i start mine up and its usually at about 1000 rpm's but when i idle it hits 500-750 occassionally and seems like its going to stall a little bit... I took it in to get it checked out the guy said it was the o2 sensor.. but uh like i said not sure if that'll help cuz yours is idle'ing really high instead lol

TripleHmotosports

Is the engine Carb,CFI or EFI?

FoxbodyMech

throttle body injected so kinda carb, kinda EFI lol

TripleHmotosports

There is a choke pulloff diaphram that is probably blown. It is located on the left rear of the TB, you have to remove 2 screws that hold the housing on. The diaphram is inside. It also has a vacuum line running to it. The diaphram unscrews from the choke rod, mark the threads so it goes back on in the same spot. Probably a Dealer or Motorcraft item. Check to make sure the choke cap is working properly and voltage going to it also.

FoxbodyMech

Yeah, i'm not too sure. I think my o2 sensor REALLY needs to be replaced. Oh well, she's getting a nice cleaning up and replacement of parts soon, so i'm just gonna go through and test everything and make sure she's up to par.