94irocz

The other day I threw a SES light for bank 2 o2 sensor, and a map sensor code. My right o2 sensor hardly moves on my freescan. Hovers right in there at 330-400 and doesn't move around like the left one does its all over the place from 001 the whole way up to 980 something. But watching my map sensor reading it just kinda sits there right in the low 500's on my freescan. How does it work and should it move? Basically the car runs like pure dog crap for most of the time. Bucking and surging then it'll clear right up. I know the right o2 sensor is dead. But does the map sensor needs replacing as well.

Severous01

at idle it should read .5v. and at wot it will read around 4.5v. anywhere in the middle depending on vacuum and throttle positions.

your ox sensors should be bouncing between .200 and .800, switching about every second or second and a half.

shoebox

http://members.aol.com/InjuneerZz/ScanMast.htm

94irocz

Thank you, injuneer and shoebox to the rescue.

elisowski

If the O2 readings are stuck, you have a bad O2 sensor. The 300-400 range is really lean and the computer is most likely adding a ton of fuel to that side making it run pig rich. Or, it is keeping it in open loop operation and calculating your Air to Fuel ratio from tables that are based on your MAP sensor readings vs. coolant temperature.

Change the O2 and note the changes. Clear the codes after the O2 swap and see if the MAP sets a code again.

I don't know what the conversions are, but a stock cammed car should have a MAP of 45-50 kPa at idle and high 90s at WOT. I do know that 100kPa is approximately 0 inches of vacuum. (gauge inches).

It is opposite of vacuum readings (meaning high MAP is low vacuum and vice versa). I have a cam with a 107 LSA cam and my car idles at 68 kpa @ 1000 rpm.

Injuneer

A stock cam will usually run 32-35kPa at idle = about 20"Hg vacuum. The corresponding values for voltage, "hg and kPa are in the link Shoebox posted. It also explains the effects of altitude, which could significantly lower barometric pressure, and hence the maximum available WOT kPa. Also explains how to calculate vacuum from BAR and MAP.

elisowski

My mistake, I forgot that my car had a GM Hot Cam in it when it idled at 47 kPa. Sorry for the bad info.

user 647483

Don't happen to have that info saved somewhere do you?
Hometown has been shutdown

Injuneer

As indicated in my "signature", my website has moved:

http://www.injuneer.com/ScanMast.html

user 647483

Thanks ... bookmarked