Rough Idle on 1983 Volvo 244

Hi, Last week I bought a 1983 Volvo 244. I have read a lot about the
240's and decided I really wanted one. It has 150 K, automatic trans,
OD works fine, brakes seem almost too good, the body is perfect, cloth
seats, hand crank windows, no AC. The oil looks good, the coolant
looks good, the spark plugs look new and are bosch platinum, wires
new, air filter is new, new radiator, new dist cap and rotor.

The idle surges at a rate of about once every 4 seconds. I am a
little worried it won't pass emissions in CA without making the idle
better, although it hasn't stalled on me yet. It seems like it might
be a little better some times than others, maybe better after warming
up.

 

A good place to start is the CIS in the LH jetronic system. Here are a few
things that could be wrong:

1.) Air control valve in CIS system is bad
2.) air leakage in vacuum lines
3.) CO2 adjustment is wrong
4.) ignition timing is off
5.) throttle butterfly needs adjusting
6.) ECU is bad

I would start with # 1 & 2 as these are the most likely. Good luck !!

1983 240 GL - 300,000 miles and still ticking.