hello:

i just picked up a bertone (with the PRV) a week ago. This car runs great as far as i can tell. made the 100 mile trip home from seller with no problem. a closer scrutiny of the engine compartment revaled that the PO had disconnected the O2 sensor. With the engine running and warm, I re-connected it and the idle became somewhat rough. the engine didn't stall, though. I tried this with engine cold, engine idled OK, but after a couple of minutes, it's back to that somewhat rough idle. what could the likely problem be? thanks guys.

The causes could number as many fingers and toes you have to count on--but some common causes---intake manifold seals leaking-spray water vapor or carb cleaner around base of manifold and listen for variation of idle---defective or clogged O2 sensor---incorrect mixture at CPR-do you hear the frequency valve buzzing as it should? There are three idle air bypass screws at the front of the manifold-folks like to fiddle with them-read up on the proper adjustment---mechanical defect-worn cams and rocker arms are common-is there excessive valve clatter?---Tune up parts up to snuff?-ignition wires are a common problem with the recessed spark plugs. Others will chime in I'm sure. Good luck---Dave

Good news is your Lambda system is working.
Bad news is, that's about all that is working right.

O2 was probably disconnected to run a baseline tune, without the Lambda loop interfering. Leave it disconnected:

Look for any vac leaks in the hoses,injector seals and manifolds.
Set timing
idle
mixture

Hopefully it will have slowed down and smoothed out. Plug in the O2 and see how it goes. Should be little to no change, slight idle drop.

If you give the throttle a blip and it dies on you, god help you. I chased that for months and eventually did what your PO did; and ran Lambda-less until I could distance myself from the car.

Wish I knew about this: http://www.k-jet.org/
back then. Read up!
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71 ID21F - 88 CX GTi - 84 244Ti