Wide band oxygen sensor

[kelvin]

Sorry, I'm sure this has been asked before, just need a straight forward answer. Just put a cam in my Ecotec and it runs really bad. I'm a bit confused over VE tables in relation to a/f ratios, but that's another issue. Anyway I wanted to install a Wide band O2 sensor and measure the voltage to get an A/F ratio. Will this still be OK on the standard computer. Any recomendations on a suitable single wire unit and does it come with a voltage to A/F conversion chart.

[Jayme]

um? An ecotec has a MAF, no such thing as VE tables in those tunes.... unless you have converted it to a different PCM yourself? also given the MAF it shouldnt run too bad even with a cam change.

you can get pretty much any wideband controller. you cant just buy a sensor, you need a special contoller as well. I use these guys: http://14point7.com/Products.php

[kelvin]

Hi
Thanks for that. I didn't tell the whole story. It's an Ecotec in a VN, using the VN computer. It ran really well before I rebuilt the engine. Now blows clowds of black smoke on idle. No fault codes. I was thinking that when it warms up and runs at 14.7, will the closed loop correct the mixture. Not too sure what I'm talking about here.

[Jayme]

oh yeah thats normal for a cam using a map sensor, they move the efficiency range up to a higher RPM so it is less efficient down low which means it requires less fuel. this makes it really rich at idle and low rpm. yes, youd need a wideband to fix it completely but if you are experienced enough, you could get it better by reducing the fuel a bit down low and playing it by ear.

are you using the standard VN tune at the moment or was it custom tuned for an ecotec?

[kelvin]

It's basically a standard tune with little mods like rev limit, idle speed, cooling fans cut in.
The funny thing is, when I first started the car after the rebuild, I just turned the key with no throttle. It was a little hard to start, but fired up after a while and idled just like a standard cam. A bit disappointing, I thought. After a couple of minutes idling, I revved it, just a little and then that's when it went fully rich and wouldn't idle under 1200 rpm.

[Holden202T]

well it probably ran alright when it was cold because the idle is higher until it warms up, then revving the engine above 2000rpm resets the IAC then thats probably were your issues start.

if the cam needs a higher rpm idle then its fairly likely the vaccum at idle is changed somewhat and will be most of the issue your seeing.

[Dec_head]

Yeah another thing to watch is if you use ngk plugs running rich will kill them pretty quick

[Holden202T]

well i wouldn't say it kills them, but it fouls them up, i regularly have to remove and clean the plugs in my gemini cause its a bit cammy and does alot of idling in and out of the shed at the moment!

[Holden202T]

well as you could see this wideband thread was getting a bit off topic with spark plugs so i have split the sparkplug stuff out to Here

[kelvin]

I've taken it for a bit of a drive and it seems to have settled down a bit. But now my programmer seems to have died. A blank check says it isn't empty after a LONG time on the eraser. Read the buffer and it shows all 90H's. Looks like a couple of stuck bits to me. Tried a different computer and cable, same thing. Anyway, I've ordered a new programmer. Any discussions anywhere on VE tables and A/F ratios. It's not too clear to me.