Supra Forums banner

1 - 20 of 22 Posts

·
Banned
Joined
·
2,385 Posts
Discussion Starter #1
Hey guys, I have a VPC/SAFC2 and an FJO wideband. VPC at 12 across, SAFC2 set on hotwire 12 12 1 1.
When my car is cold and im ready to drive off my a/f's will ride up to 19.2 then come back down to 14.7 1st 2nd and 3rd. When the car is warm it is normal 14.7-15.2.
Any ideas why the a/f will ride up when the car is cold?
This is just when its cold and im leaving to go wheverever. Its not WOT.
Thanks Ryan
 

·
Registered
Joined
·
1,255 Posts
one reason - when car is cold, gas doesn't combust... so there's a lot more oxygen in the air and thus your high A/F.

normally cars prevent this by dumping more fuel in when the o2 sensor is still cold.

you may want to check our o2 sensor.
 

·
Republican
Joined
·
8,421 Posts
because the o2 sensor hasnt heated up... it takes about 45 seconds to fully heat up
 

·
Banned
Joined
·
2,385 Posts
Discussion Starter #4
Well when I say cold, i mean the car has been warmed for about 5 mins or so. So its not like im starting it and driving right away, I let me car warm up a bit before taking off. Any ideas?
 

·
Newbie
Joined
·
11,221 Posts
Ckanderson said:
because the o2 sensor hasnt heated up... it takes about 45 seconds to fully heat up
Yes, something like that. I'm about to install the Innovate wideband kit. On the instructions it says that the sensor has to fully warm up before it reads accurately. It doesn't say how long though. But on the screen it'll be like "warming up: 55% complete".
 

·
Newbie
Joined
·
11,221 Posts
sensors are known to go bad after a while. I mean if you say the a/f will go back down after car is warmed up, then I guess that is when the sensor has fully warmed up too.

Also what does the vpc temp sensor have to do with the wideband? I'm asking because I just installed a vpc/safc2 combo yesterday, and I'm gonna install my Innovate wideband tomorrow (hopefully).
 

·
Newbie
Joined
·
11,221 Posts
Spoolin Turbo said:
well im wondering if its the VPC sensor sending a signal and causing the wideband to read the way it is.
But even when its fully warm it does the same thing. Any idea?

Huh? I thought a wideband is fully independent. It runs on it's own o2 sensor...
 

·
Republican
Joined
·
8,421 Posts
I really wouldent worry about it..
 

·
Banned
Joined
·
2,385 Posts
Discussion Starter #12
problem still persists. I reset the ECU and its still doing the same thing. It seems occur mostly in 1st gear and the car gets to 20.0 and will stutter for a bit.
Anyone have any ideas?
Thanks Ryan
 

·
Newbie
Joined
·
11,221 Posts
Beats me bro. Worse way is to just buy a new sensor. I mean sooner or later you will need a new sensor anyways, so just shove out th e100 bucks now and store the sensor for later use.

Aren't you supposed to be more worried about your a/f in 3/4th gear anyways?
 

·
Registered
Joined
·
1,255 Posts
as i said in the 2nd post, try checking your primary o2 sensor.

when o2 is cold, there's no reading for ECU. ECU doesn't know much gas to put in; if o2 sensor was giving the wrong reading when it was cold, it could lead to any number of fuel problems, including what you may be experiencing.


you may also want to check the engine temp sensor. when your car is cold, it needs more fuel for combustion. it sounds like you're not getting enough. if the engine temp sensor is giving a wrong voltage reading while cold, the ECU will not give you the proper amount of fuel.

i'm unsure if the ECU uses the 02 sensor + engine temp sensor, or some combination of the two, but both of these sensors could result in the troubles you're having.
 

·
Banned
Joined
·
2,385 Posts
Discussion Starter #20
well if the primary O2 was bad wouldnt the car throw a code?
There are no codes when I checked today.
Ive now been monitoring the prob. Cold start its fine, its when it warms up is when im getting the prob. It seems to occur mostly in 1st gear just pulling off.
It occurs when on the throttle, not off. I know it goes to 20.0 when off but thats normal.
What are the signs of a bad intake air sensor?
 
1 - 20 of 22 Posts
Top