Erratic A/F Ratio under Cruise

[DrGonzo]

Poor grounding could also cause TPS noise.

You could also need to recalibrate your TPS. Does it read 100% at WOT? What does it read at idle? Is your idle switch on at idle?

I don't think it is supposed to read 100%. According to the manual you adjust it by setting the idle switch, if the Idle switch is set correctly then it would never see 100% open, Atleast the last four I adjusted where like that. Once the Idle Switch was adjusted correctly on the TPS WOT would get me about 94-96%.

[BigTyla]

I don't think it is supposed to read 100%. According to the manual you adjust it by setting the idle switch, if the Idle switch is set correctly then it would never see 100% open, Atleast the last four I adjusted where like that. Once the Idle Switch was adjusted correctly on the TPS WOT would get me about 94-96%.

That sounds familiar. I've been away from the 3S platform for awhile now and pampered by the capabilities of DSMLink so I'm more familiar with adjusting it via the ECU.

But to confirm, your idle switch works properly, yes?

[Roybatty]

That sounds familiar. I've been away from the 3S platform for awhile now and pampered by the capabilities of DSMLink so I'm more familiar with adjusting it via the ECU.

But to confirm, your idle switch works properly, yes?

3S don't have a switch AFAIK, that is exclusive to the DSMs. If you set the tps per manual you will have the slightest slack in the throttle cable. My tps reads 12.5% closed (MMCd); @ this point the tps signals to ecu idle condition. I agree with Gonzo regarding the upper boundary of tps.

[BigTyla]

IIRC my 3S had about those same numbers (12.5% closed and high 90s% open)

[HLxDrummer]

Dunno how to check the idle switch, but the TPS reads around 12% at idle and 93% at WOT.

What do you want me to log?

My air leaks are fairly minimal last time I checked and I've recently fixed one of the leaks... (PS does anyone know the part number for the PCV hose that runs from the front to rear bank on the driver's side? Mine just cracked )

Edit: Oh and I have new ground wires off the battery but most other wiring is stock. Nobody thinks it has anything to do with the fuel system?

[Roybatty]

What do you want me to log?

My air leaks are fairly minimal last time I checked and I've recently fixed one of the leaks... (PS does anyone know the part number for the PCV hose that runs from the front to rear bank on the driver's side? Mine just cracked )

Edit: Oh and I have new ground wires off the battery but most other wiring is stock. Nobody thinks it has anything to do with the fuel system?

Your write up says you have lc-1; log afr, air and fuel data during condition. For example; if IPW or IDC changes but not air flow, should point to unmetered air.

I replaced the PCV hoses with reinforced (transmission cooler lines) 7/16" and 3/8". If you hound the guy @ Autozone he will sell some of the scrap pieces cheap. They will see some boost; @ least till u get Krank Vents.

I would check the obvious on fuel; pressure, pump working, electronic checks, but I don't see why you would rule out air.

[HLxDrummer]

Well the IDC is a function of TPS, O2s, etc as well right? So airflow could be constant but TPS change/etc. could change IDC? I'll give it a go sometime soon though anyway and see what I get.

I would like to test the fuel system but have no way of doing it without buying a bunch of stuff. For example, how can I test the pump? I also have no pressure gauge or place to put it yet unless I buy stuff to install my AFPR.

Thanks for the PCV info!

[DrGonzo]

3S don't have a switch AFAIK, that is exclusive to the DSMs. If you set the tps per manual you will have the slightest slack in the throttle cable. My tps reads 12.5% closed (MMCd); @ this point the tps signals to ecu idle condition. I agree with Gonzo regarding the upper boundary of tps.

The Idle Switch is built into the TPS sensor. On MMCD you can see when it is on by looking at the FLG0 on page 3. The "I" at the end means idle switch.

Here is what the other mean

*FLG0
A: Air conditioning relay
F: Fuel pump relay
B: Boost solenoid

*FLG2
T: Top Dead Center
S: PS Load Switch
A: AC Load Switch
N: Neutral
I: Idle Switch

The manual has you connect a multi-meter to the Idle Switch wires on the TPS and adjust it till it just turns on when the plate is closed. It is usually about 12.5% open.

Mine is 7.8% right now so I know it is off as I can look at the logger and see the idle switch stays on until it gets to about 13% throttle. Have to add that to my list of things to fix...LOL

[mb3000]

MD347321 if you want OEM

[HLxDrummer]

Thanks for all the info guys. I guys I should call this thread, "Erratic AF Ratio". I took it to work today and the AF is all over the place all the time. From 14-19 under cruise! I have attached some logs under idle, light load, and normal driving.

I also checked the idle switch, and it is functioning properly.

I am kind of ruling out fuel leaks temporarily simply because my MPG is awesome (170 miles on a touch less than 1/4 of a tank).

If I had a jack/stands at school I could make sure there are no pre-WB exhaust leaks but unfortunately I don't. I don't hear anything, though.

Any ideas? Is it worth going into the cold and checking voltage at the pump (I hotwired/soldered it but I'm relatively new at soldering).

Edit: Well the best log won't work for some reason but we'll see what you can do with these three. Also, this forum won't let you upload logs more than 19kb?!

http://dl.dropbox.com/u/38123737/201...7_55_04txt.txt
http://dl.dropbox.com/u/38123737/201...7_59_48txt.txt
http://dl.dropbox.com/u/38123737/201...8_01_07txt.txt
http://dl.dropbox.com/u/38123737/201...8_01_41txt.txt

Edit: Forgot to mention that my wideband is listed under batt as (XX.XX V)