AFM adjusted on 3FE MUCH BETTER!

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Timpanogos Slim said:
Well, it would tell you if things are grossly out of whack.

Seriously, I've seen the exhaust manifold of an olds 455 glow cherry red at night in december. It was running WAY too lean.

I'm under the impression that a good wide-band A/F meter is going to cost bucks. Looks like about $160 up to however much you want to pay.

I don't know if you could piggyback the existing narrow-band and learn anything.

EGT sensors are relatively cheap, but i have no idea where on the exhaust manifold of a 3FE you would put one.

On a 93/94 1fz I'd say delete PAIR, and drill/tap one of the (very meaty) OEM blockoff plates.
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Most affordable infrared thermometers typically have a maximum capability of under 1000 degrees. It would be useful only to diagnose a cylinder not firing.

At idle a gasoline engine is runs 700 to 800 degrees and will run under light load over 1000 degrees. An engine under heavier load is going to be 1300+. Operating lean it can get 1500+ in a few seconds. You can watch the gauge climb and fall as you ascend and descend small grades. Closing the throttle and going back to idle it takes just a few seconds for the temps to drop back down. You don't have to run 30 minutes on the highway. Measuring the manifold heat after stopped won't be very informative. A diesel motor will run much cooler.

Wide band sensors are relatively new. Bosch made the first ones back in '94 and I would say they weren't widely available until after 2000. Yes the sensors on our trucks can be monitored. The $30 variety read the voltage from the sensor. You should get a fluctuating output voltage between 0.2 and 0.8 volts, with an average of about 0.5 volts. A voltage reading that remains low (close to 0.2 v) or high (close to 0.8) means the engine has a lean or high fuel ratio, respectively. The fluctuations vary in speed based upon engine RPM. At highway speeds that sweep can be 3 to 5 times per second. At idle it might be on sweep every 5 seconds. More advanced meters will take and process the voltage and display a weighted average. The ratio changes constantly so that the catalytic converter can function properly.

EGT probes can easily be added to the down-pipe. There are probes that use a welded in bung but there are others than use a small hole with a self-sealing type of band clamp. The closer to the exhaust manifold the better but any place prior to the cats will still work without issue.
 
ppc said:
Wide band sensors are relatively new. Bosch made the first ones back in '94 and I would say they weren't widely available until after 2000. Yes the sensors on our trucks can be monitored. The $30 variety read the voltage from the sensor. You should get a fluctuating output voltage between 0.2 and 0.8 volts, with an average of about 0.5 volts. A voltage reading that remains low (close to 0.2 v) or high (close to 0.8) means the engine has a lean or high fuel ratio, respectively. The fluctuations vary in speed based upon engine RPM. At highway speeds that sweep can be 3 to 5 times per second. At idle it might be on sweep every 5 seconds. More advanced meters will take and process the voltage and display a weighted average. The ratio changes constantly so that the catalytic converter can function properly.

EGT probes can easily be added to the down-pipe. There are probes that use a welded in bung but there are others than use a small hole with a self-sealing type of band clamp. The closer to the exhaust manifold the better but any place prior to the cats will still work without issue.
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Thanks. I'll look into a pyrometer too.

Always in favor of more instrumentation.

On 93/94 it appears that those squeamish about splicing wires can just solder some tabs onto the end of the AFM harness and jam them into specific sockets on the diagnostic connector under the hood. Perhaps the 3FE setup is similar.

My AFM is on it's way from the far east as are arduino bits so i can start working on a combined digital display with peak holding.

should be possible to tap the signal from the trans temp sender too.
 
but......do you get better mileage????
 
resetting your ecu by disconnecting the battery will not give it "bad "readings....it starts collecting new data....
 
3FE reporting back

Temp: Took my cheap infrared sensor and hit the manifold. Noticed that right at the flange between manifold and downpipe I got the highest temp at 420F. I'm not too worried about that.

Bad or NO Low Idle: I went ahead and reset the ECU (took EFI fuse out for a while). Now the idle seems screwed up. When I start it it gets up to 1000-1100 RPM. I drove home last night and let it sit and run for 10 minutes and it didn't get below 1000 RPM. This is when I took the temps. I knew I shouldn't have reset the ECU! Just kidding, probably didn't do anything.

Questions:
How long does your 3FE take to warm up and idle go down to 650RPM? I think before if I left mine sit and run for 10 minutes, that would do it and it'd go down.

Should I mess with the idle flathead screw on the throttle body? It seems like the ECU is controlling this, so I don't know if the screw would help.

TPS? I'll look through the FSM tonight about the TPS and do some ohm diagnosis on it this weekend. I didn't touch it, but I don't think messing with it is going to hurt anything.

Kind of ironic that it's acting like it doesn't know it's warmed up and I'm worried it's getting too hot at the same time.
 
The cheap a/f gauge that reads off the o2 sensor will not tell you anything useful. You need a wideband a/f gauge for useful data. If your a/f ratio is where it should be, your egt will be fine with stock timing.
 
bsmart82 said:
The cheap a/f gauge that reads off the o2 sensor will not tell you anything useful. You need a wideband a/f gauge for useful data. If your a/f ratio is where it should be, your egt will be fine with stock timing.
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Would you mind explaining why a wideband is needed for useful data?

and of course the EGT will be fine with stock a/f and timing. why does that even need to be said? what about this thread gave you the impression that anything was staying stock?
 
jcarter said:
Temp: Took my cheap infrared sensor and hit the manifold. Noticed that right at the flange between manifold and downpipe I got the highest temp at 420F. I'm not too worried about that.

Bad or NO Low Idle: I went ahead and reset the ECU (took EFI fuse out for a while). Now the idle seems screwed up. When I start it it gets up to 1000-1100 RPM. I drove home last night and let it sit and run for 10 minutes and it didn't get below 1000 RPM. This is when I took the temps. I knew I shouldn't have reset the ECU! Just kidding, probably didn't do anything.

Questions:
How long does your 3FE take to warm up and idle go down to 650RPM? I think before if I left mine sit and run for 10 minutes, that would do it and it'd go down.

Should I mess with the idle flathead screw on the throttle body? It seems like the ECU is controlling this, so I don't know if the screw would help.

TPS? I'll look through the FSM tonight about the TPS and do some ohm diagnosis on it this weekend. I didn't touch it, but I don't think messing with it is going to hurt anything.

Kind of ironic that it's acting like it doesn't know it's warmed up and I'm worried it's getting too hot at the same time.
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high idle is normal after resetting the ECU. Give it about 8 drives.
 
I agree it needs a few drive cycles to iron itself out.....not just idling
 
Timpanogos Slim said:
Would you mind explaining why a wideband is needed for useful data?

and of course the EGT will be fine with stock a/f and timing. why does that even need to be said? what about this thread gave you the impression that anything was staying stock?
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The cheap a/f gauge is just a light show. A real wideband even a cheap one will tell you the actual a/f ratio. Obviously the truck will try to maintain stoich in closed loop as long as it has room for adjustments via fuel trims, but open loop is preset based on a fuel map dependent on load which is airflow vs. rpm. Once you go adjusting the afm, when you tighten the spring you are essentially leaning it out by reporting less load. Too lean can be dangerous, cause high egt, knock, etc. You could read the plugs and listen for knock, but it's easier with an a/f ratio gauge. I mentioned egt because someone else did before me. We are only discussing fuel here so I assume stock or a few degrees advanced timing which is fine, because timing can have a dramatic effect on egt as well as fuel. My rule of thumb for a/f ratio is 11.5 for boost, and 12.5 for n/a for max power. Every engine will like it a little different, but if you stick to around 12-13 a/f ratio during open loop you should be fine.
 
Yeah I know too lean is dangerous. That's why I'm adding instrumentation.

You'll have to try and give me a more technical explanation of why the narrow-band sensor isn't going to tell me anything useful. Because at the moment you sound like you're repeating something that some guy at a performance tuning shop preached at you. And I know first hand that some of those guys are full of crap.

I'm very technical. I understand basic energy physics. Don't hold back.
 
An o2 sensor reports 0 to 1 volt and is made to operate around 14-15 to 1 air fuel ratio. This is fine for the ecu since it only targets 14.7 and does not care about open loop. This is certainly good enough if you just want to know if you are leaner than stoich. If I am going to adjust the afm, I want to know exactly what is going on fuel wise so I can extract the most potential out of the engine and be safe at the same time. Google tuning basics and read till your head hurts. I have been researching tuning since 2005 when I boughty first Talon and starting tuning. I have tuned a few cars over the years. I am no expert and I only have experience with forced induction, but a lot of the principles are the same for naturally aspirated. Basically narrow band will tell you yes or no, and a wideband will tell you the exact number.
 
Also realize that my point of view is from tuning a 2 liter with stock internals pushing 30+ psi of boost. The tune has to be spot on so I like to know exactly what's going on. The 1fz is pretty stout so you could probably get away with a little lean and be just fine.
 
jcarter said:
Should I mess with the idle flathead screw on the throttle body? It seems like the ECU is controlling this, so I don't know if the screw would help.
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A 3FE doesn't have an idle adjustment screw. The screw you're referring to sets the static air flow at the throttle body intake. It does have a temporary effect on idle, but the ECU will adjust idle with the ISC valve. The correct position is 1/4 to 1/2 turn out from full seat.
The more you try to adjust the idle with that screw, the more the ECU will compensate by pushing the ISC.

It is normal for a slightly higher idle after resetting the ECU. Like others have said, it takes a while for the ECU to relearn.

Enjoy the truck and don't concern yourself with fuel economy. The more power you have the more you want to use it. Just drive it.
 
High-Idle, 1 more week

Okay Mr. Jonheld, I'll leave it another week.

I was just getting online to update that I'm putting the previous AFM back in to see if the idle goes back down. But after reading your reply, I'll leave it another week (I can afford the extra $20 in gas).

Long Drive: Hopefully the high idle is because I haven't driven it that far yet and it's been cooler outside this week. I drive 1-1/2 miles to work and really haven't had to drive any further. Today I'm going downtown about 15 miles on the interstate, so I'm hoping by the time I get there and park the idle is back to normal.

Still got it! The power is still there and I LIKE IT!

Frustrating :bang: I don't understand why I make the change, start it up and after a few minutes the idle is a perfect 650 RPM. I post it up on the MUD. Next day, take it on a VICTORY DRIVE for about 30 miles or so with perfect idle and much more power and life is good! Back to my normal routine and the idle won't go down. How the heck can this be? I finally get her tweaked to run well and BOOM! another issue.
 
Reporting Back after 10 days

Still have the high idle, 1100 to 1200 RPM in park/neutral; 900 stopped in gear (light on "D" just went out, bummer).

Yesterday, I was running back and forth to the hardware store and noticed when I got back on one of my many trips, IDLE WENT RIGHT AGAIN! 650! Stayed there stopped in gear, put it in park, it reved up a little and quickly went back down to 650.

Slow learning ECU! I've watched it when its just warm: idle in park, wait a while, idle begins to go down slowly, 1200-1100-1050-1000-950, then back up to 1200. Like the ECU is listening to it's inputs; slowing the idle; then thinks "nope, I'm still cold, let's go back up to 1200 RPM"

It's weird, but I don't think it's hurting anything. Still runs a whole lot better. I'll look at it in the spring, too busy and going to get too cold to mess with it till then. Hell, maybe the idle will get back to normal by then.

"stuck plate" I'll try it, but have already popped the pedal (like in old cars to get idle down) that should have fixed anything sticking.

"gas mileage" Haven't gone a whole tank yet, but it'll be pretty bad with the high idle.
 
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