Do boats use an o2 sensor?

[slimfitz]

Just curious here. I got to thinking about my motor. Im not sure if I have a o2 sensor. I have a 97 Volvo 7.4 LK model. How does the motor adjust the fuel and timing if it doesnt measure the unburned gases? I know it uses a map sensor but I cant seem to find an o2 sensor on the exhaust side. I assume it runs in open loop? Just using a pre determined fuel map?

 

[Sherminator]

Re: Do boats use an o2 sensor?

If it is a Fuel injected engine, more than likely it will have some sort of O2 sensor. If it is a carb you probably will not have one.

 

[agallant80]

Re: Do boats use an o2 sensor?

if it is newer and has cats there will be one before and one after each cat. I have 4 on my boat.

 

[slimfitz]

Re: Do boats use an o2 sensor?

Well I have searched my exhaust and do not see them. Where would they be located? I would imagine that it is going to be on the riser? I even went through my parts diagram. They dont show one either.

 

[slimfitz]

Re: Do boats use an o2 sensor?

Just to clear things up. My boat is probably the first year of fuel injection. It is a 1997 Volvo Penta 7.4 LK. I have no cats. I didnt even know that cats were on boats now. I guess emissions is now an issue with boats. I know that if it has a cat it has to have an o2 sensor just so it can correct the mixture. Did the early boats just run on a pre determined fuel map?

 

[Don S]

Re: Do boats use an o2 sensor?

Actually, 94 was the first year Volvo used EFI
You do not have an O2 sensor on that engine.
This should explain how it works.

View attachment 7797364_LK_EFI_Diag_GM_BW_Cover_W 20.pdf

 

[slimfitz]

Re: Do boats use an o2 sensor?

Thank you Don S, that makes alot more sense now.

 

[E4ODnut]

Re: Do boats use an o2 sensor?

Slim,
Don's reply is correct. You are also correct in that it runs open loop (with respect to Exhaust Gas Oxygen feed back) on a predetermined program. No doubt an O2 sensor was used to determine that program. As far as I know the latest flavors of marine EFI now use an O2 sensor and closed loop to keep a tighter control on emissions.