^VooDoo^

Does anyone have an airfuel meter on there 3.0?
I have one as a kinda handheld and Im trying to use it to track a sevear leanout problem Im having.
Its a LED leniear type with 9 LED's scrolling around the curcle marked lean to rich.
What Im getting at idle is constant back and forth rich to lean and back every 1.5 seconds

Is this normal for idle?

chimmike

that means that the o2 sensor itself is a narrowband unit. You cannot use something like that autometer gauge anyways and expect it to be accurate. In order to get an accurate air/fuel reading, you need a wideband o2 sensor setup, something like Innovate makes... www.innovate.com or like the AEM UEGO wideband sensor setup.

running those autometer garbage gauges is more for show than anything, they're essentially worthless. Besides, you don't want the motor running at stoich under heavy load!

Bumpin' Yota

yeah what he said!

And to add to it, yes the sweeping is normal. And while you are in open loop operation, the sweeping rate will increase with RPM. When you hit closed loop (usually above 80% throttle) you'll see it stabilize on the rich side of things. 100% normal!

Interestingly enough OBDII's o2 sweeps are MUCH faster than OBDI's

dcg9381

It's accurate.. at 14.7:1 or so anyway.. It'll give you an indication of lean or rich, so it's not worthless..

What you're talking about is called dithering.. 14.7:1 is a bit lean for idle, but possible... Dithering is normal for closed loop operation. Using the 02 (closed loop) at idle is possible, but I dont know if it's normal operation...

^VooDoo^

Bumpin, Thanks, thats what I needed to know, Ive been trying to track a trouble of severe leanout for months now with no CEL codes what so ever.
(Yes the CEL works)
I can force a CEL by sabotodging sensors, EGR (71) temp had take 2 day to come up though.
It was sudden and cannot seem to track the trouble but Idles fine, Timing is right, No missfire\backfire and no vacuum leaks.
No HG trouble, Comp test is good and even considering the miles.
I have replaced everything except ECU, AFM and injectors, I still use it as my daily driver and on cold days I can barely get above 60 on the flat, This must be due to the air density going up but not fuel input, THe AFM ohms out as good. (I jumped it 8pts richer but no improvment or change and that should make it poor black smoke out)

I know my EGT has to be through the roof sometimes.

chimmike

I know what you mean by wanting to check, my runner is doggedly slow right now as well, far worse than my mom's 94 3vz auto was a number of years ago. I've done the air filter, doing a PCV valve this afternoon, finishing up the plugs (which looked like hell) and doing plug wires. I'm thinking a high flow cat might help as I bet the catalyst is clogged to hell with crap.

voodoo: Go to advance auto and buy Sea Foam fuel system cleaner. Run one can thru a tank to loosen things up, then run a 2nd can thru the tank to flush it all out. Check your plug wires, coil, air filter, spark plugs, PCV valve.

I think also I'm going to check my throttle body/clean it a little with some sea foam, you might want to check it out too.

^VooDoo^

Ive done the Seafoam already, I have been using fuel addatives to help with the pinging.
Just replaced the Fuel pressure regulator for the 4th time on a bet with freind and still no good, I do and have noticed that when I pull the EFI fuse I can get some descent power untill the ECU seems to try and compensate then it all seems to lean out.
That seems to make me think that the ECU might be reading the O2 sensor backwards then goes into protection mode, But as long as its getting a reading from the O2 sensor it wont show a CEL.
BTW, I havent changed the Knock sensor but again why would the engine go lean if that went bad.

chimmike

sounds like your issue might be with a dirty MAF sensor....

dcg9381

That's a good guess.. A dirty MAF (esp if you've run oiled filters) will cause air flow to read low and the truck to run lean... Saw this on a buddies supercharged 3.4... You could see it on the wideband.

Replaced/cleaned the MAF and we were well into the green lights at WOT.

mt_goat

The 3.0 doesn't use a MAF, it's an AFM and the AFMs don't use the dirt/oil sensitive heated wire method of measurement. The AFM have a spring loaded flap that measures the air flow.

Have you checked the fuel filter?

mt_goat

On my truck at idle I'm staying real close to 14.7. It will maybe drop to 14.6 or up to 14.8, but usually not much more than that kind of variance. Oh its a wide band A/F sensor (Innovate)

^VooDoo^

Thanks people, Ive made some headway with my problem but it looks as a multiple part failure amongst other troubles I have had.