Checked the duty cycle on my 84 wagon and reset it to 50% assuming that this is the optimum value, but it has seemed to have leaned the engine out some. Does anyone have the recommended value? I have a Haynes manual that does not mention a value, I have heard the Bentley manual may have the recommended setting. B23F engine. JD
I've heard conflicting numbers, what I ended up doing was measuring a well-running Kjet 240 and setting mine to match it, the adjustment is very sensitive though, best not messed with unless someone has already messed it up.
He said right in the original post, B23F engine, that's a non-turbo 2.3 liter.
OK. Then does it have a CI system or LH or whatever else Volvo used in '84?
Bob
It has CIS (K-jet), otherwise there'd be no duty cycle to adjust.
What I mean by the duty cycle is the amount of times the O2 sensor goes from lean to rich. I have heard that this can be set with a led off the lead next to the coil but I must be doing something wrong. Manuals refer to the Volvo Monotester but I can't get a decent reading off my dwell meter. I have looked and have yet to find the definitive method of setting the O2 sensor frequency, duty cycle, CO level or whatever you would like to call this adjustment. It appears to be a necessity for achieving the proper fuel-air mixture. jd
A dwell meter set for four cyl between the pink test lead and ground, engine running, will show 53.7*, O2 sensor disconnected. The setting value should be between 45*-55* engine idling at ~850rpm, warm, throttle switch contacts closed, dipstick fully seated, no vacuum hose leaks, ignition showing between 5*and 10* BTDC.
This establishes the mixture setting at idle. All other mixture corrections during running are regulated by the control pressure and manifold vaccum changing the height of the air flow sensor plate above the venturi. There is virtually no correction for restricted injectors, leaking injector seals, or faulty pressure regulation. The theory being that if the idle setting is close enough at idle then the converter and the above mentioned controls will be more than adequate to maintain an emission level within the regulation in effect at the time.
Bob
In 1984 Volvo referred to injector open time as dwell, prior to the current jargon of referring to pulse width modulation. Using the same test lead as the OP mentioned you could adjust the mixture, hence the injector dwell, just by reading the voltage sweep at the test point. Same procedure just different numbers.
Bob
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