Volvo CFI system

Greg Hermann bearbvd at sni.net
Thu Sep 17 18:01:34 GMT 1998


>Hi Group !
>	Hope someone can help. This is not really an EFI question, the old Volvo
>240 (1977) uses a continuous mechanical fuel injection (CFI) system, but
>this one has an O2 sensor and what the manual calls a "frequency valve"
>which apparently adjusts the mixture in response to the sensor. After
>260,000 trouble free miles, the ol' tank no longer passes emissions for
>hydrocarbons, this accompanied by a slightly rough idle. CO is just fine,
>~1%. Compression is OK, 120lb - 130lb, all new ignition parts, tried
>swapping in different distributor, coil, CDI box, O2 sensor, disconnected
>evaporative emissions, checked fuel pressure, injectors and cold start
>/fast idle components, and finally pulled and cleaned the entire air valve
>/ fuel regulator assembly (a real pain BTW). Same stinkin' problem.
>	I have observed that disconnecting the "frequency valve" seems to smooth
>out the roughness in the idle, but lack the electronics to test the HC
>emissions under these conditions.
>My question is, then, does anyone have any information regarding this
>proto-EFI system, or any other thoughts which might help get my beloved
>Swedish tank back on the road for the next quarter million?
>
>	Thanks in advance!
>	Steve Jernigan,
>	University of Colorado,
>	Microelectronics Research Laboratory.
>
>PS, Has anyone successfully reverse engineered the original Holley analog
>throttle body fuel injection? Sure could use a schematic for the control
>box, and Holley isn't very helpful at all.
>TIA, again! S.

Hi Steve--

Just a thought, but are you sure that the cam timing is correct?? Maybe a
new belt a tooth off, or old belt jumped a tooth??

Regards, Greg (Sorta close by, in Steamboat Springs, but all of my Swedish
tanks have pushrods!





More information about the Diy_efi mailing list