AFM adjusted on 3FE MUCH BETTER!

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jcarter

jcarter

Joined
Jan 8, 2005
Threads
71
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528
Location
Crestwood, MO
Just screwing around today and thought I'd play with my AFM.

History: Last year I took off the "2 SCREWS OF DEATH". Bought a used AFM here on the MUD for $125. It did the job. This was during a big job to replace a piston (I posted on that too).

Spring 2013 - running rich: She just wasn't running right. "Felt" like running rich. I put in new O2 sensors and replaced the entire exhaust with EMS since I thought there was a leak before the O2 sensors throwing it off. It sounds cooler thanks to EMS and I won't be paying Midas $200 a year to patch leaks, but still didn't run real well and still felt rich. Also, I advanced the timing slightly.

Valves? I had adjusted the valves. Luckily I ran it with valve cover off and found the rocker assembly wasn't reassembled right, so oil wasn't flowing to all valves. Fixed that. Heated it back up and adjusted the valves for the 4th time. HIGHLY RECOMMEND RUNNING WITH VALVE COVER OFF! It's cool to watch and doesn't take a lot more time. You can adjust the valves while running, but you gotta be good, and I'm NOT!

That's the history, now to today.

Like I said, I figured I'd play with the original AFM, nothing to loose since she was running with the used one I bought.

I searched and found info on how to solder the connections back on. With that done, I was about to put it back on. Again, nothing to loose so did some research on how to tweak the AFM. Found that you can rotate the "cog" (wheel with teeth). CLOCKWISE=TIGHTER=LEANER. So I marked where it was, took a screwdriver and spun it 2-teeth clockwise. Realize this is a sophisticated piece of equipment, so 2-teeth means I barely moved it.
P1010373.webp

You can see the brass cog. On the left, you can see the coiled metal thing stopping the cog from spinning counter-clockwise. The way it's positioned, turning it clockwise is easy. I only did 2 teeth because if you go too far adjusting it back counter-clockwise could really screw things up (push the metal out of the way to turn it CCW and woosh, thing unspins a bunch, YOUR DONE!).

I taped the plastic cover back on and installed it. Check Engine light on with key on, so I knew the solder job worked. Took it for a test drive. WOW! Running soooo much better.

More power? Seemed to be. Took much less gas pedal for it to downshift. Seemed to accelerate better too.

Smoother idle: It used to get down to 650 RPM and idle rough. Sounded like a "hot cam" in a hot rod, "flump, flump, flump" with RPM's fluctuating slightly. Now, smooth as silk at 650 RPM.

Now the question is, can I get the plastic cap sealed properly? Must be air-tight. I'm not good at sealing stuff, so we'll see.

P1010373.webp
 
Fun stuff there. Opened mine up this summer to check it all out during a no-start problem.

"Now the question is, can I get the plastic cap sealed properly? Must be air-tight. I'm not good at sealing stuff, so we'll see."

I sealed it up with clear silicone. Use the small tubes that you squeeze not the caulking gun type. Makes for a cleaner/neater job. Looks and works great...
 
I believe the sealant used is just high temp silicone. Its really common to see silicone used for this sort of sealing/ "potting"(think potted plants) operation in electronics where water tight and air tight is important.
 
SEAL: Used the blue RTV "sensor rated" stuff. Just cleaned out the old silicon, overfilled the gap, then puddy knife to push in and smooth. Looks good and well sealed, but again, I don't have a lot of luck with these things.

TEST (hindsight-missed opportunity): Good point on the before and after. "Perhaps your solder job had a greater effect than the 2 clicks." I have 2 AFM's so not comparable. I should have soldered it, temporarily sealed it, test drove it, then 2-clicks and test drive again. Missed opportunity. With the way she's running, NO WAY going to mess with it now.

Running Rich: I think the factory settings are for it to run rich which is why there's the "advanced timing" write-up. Jonheld, I believe you once told me fuel/air mixture depends on AFM, timing, & O2 sensors. I've now covered all of these.

It's been a long journey, but now I'm feeling much more confident in dependability. Sadly, it's an addiction that is hard to break. So, soon, I will tear into the throttle body to replace the fuel pulsation damper-FPD (currently non-OEM cheapy to get it running), fuel pressure regulator-FPR, regasket the intake and throttle body, and get new injector connectors (some cracked and have zip-ties holding them in).

Professional help (admit defeat): Found a good shop called M.T. Schiele. They removed my stripped fill plug on the transfer case for me. He's into Jeeps & Toyota 4x4's. I'm going to bring it in to seal up the PS knuckle, I've tried twice and still leaking, I keep a close eye on the front diff oil level, but sick of the stench! Also, have an arm on the rear stabilizer bar broken. Lastly, I'll have him track down where all the fluids are leaking from. Funny the ONLY fluid that get's low is the front diff, but seems other fluids are leaking too.

Next project BRAKES! Probably next summer, unless I get "professional help" mentally. . . .
 
Got a link to the info on how to repair the AFM?

93/94 have the same type of device and I'm the kind of guy who voids warranties.
 
I wonder what the effects are on the 1fz. the later MAF based trucks get better mpg than 93/94.
 
jcarter said:
With the way she's running, NO WAY going to mess with it now.

Jonheld, I believe you once told me fuel/air mixture depends on AFM, timing, & O2 sensors.
Click to expand...

Yea, if she's happy then stick with it. Can't argue with the seat of the pants.

A/F mix is controlled by the ECU and the feedback it gets from the O2 sensors, air temp sensor (inside the AFM), TPS, and the position of the intake flap in the AFM.
All of these things together determine the mix. It's not just a bunch of parts, it's a system. Each sensor has to fall into a certain operational window as determined by the ECU. When a sensor is outside of that window, the ECU throws a CE light and simply ignores that sensor and goes to a preprogramed state.
So you can play a little bit with this stuff, but the rubber bands are small.
Certainly play with the AFM setting and see what you have, but I think what you'll find is that now you have a fully functional feedback system. I would pull the EFI fuse for a while and allow the ECU to relearn the settings. This should be SOP for any change in the system.

Most of all, enjoy the truck. It sounds like she's running well.
 
Could this mod cause any problems from running too lean, burned pistons?? IDK
 
Kernal said:
Could this mod cause any problems from running too lean, burned pistons?? IDK
Click to expand...

don't see why not. don't go too lean.
 
Sorry to drag this on, but it's running really really good! I took it for a 1/2 hour drive today to include an Interstate on-ramp up a long hill. Usually a killer with people tailgating and flying past me as I get up to about 50 MPH by the time I hit the top. TODAY, 65!

Why is the gas pedal so responsive now? It shifts down with much less pedal than before. Keeping 65 to 70 mph uses very little pedal where before took about 1/2. Anyone?

Dare I say this, but I think she's running better than when we got her 130,000 miles ago!

Maybe I should open up my spare AFM, tweak & test it 1 tooth at a time, then install the best setting. Run it for a few tanks of gas to check gas mileage and report back.

Since I wouldn't be messing with the connections, this would be a good test to see if the newly soldered connection helped more than the adjustment.

Sorry to seem so excited, but MAN! it's like I've unleashed the engine!
 
a/f ratio gauge? Didn't know they make those.

I was thinking about knock sensors per cylinder system. More I researched seems the hot rodders want the timing really advanced to where it's just before it knocks. I don't know about that? Like most of us, longevity is my #1 priority!
 
jcarter said:
a/f ratio gauge? Didn't know they make those.
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Yeah, in the form of a pre-catalyst wide-band oxygen sensor. Popular item for tuners.

Running too lean on a gas engine does come with several risks.

An EGT sensor in an exhaust manifold would be ideal, but you could also invest in an infrared thermometer and manually determine the temperature of the exhaust manifold after a drive.

I'm not qualified to tell you what a good baseline to compare it to is, or what would be considered dangerous. That's why an A/F meter is very handy, and an EGT sensor is too.

But i have seen exhaust manifolds glow cherry red in the dark, and i have seen melted pistons.
 
ppc said:
Using an infrared thermometer to measure exhaust temperature wouldn't tell you anything. The max temps cool faster than you can stop the truck.
Click to expand...

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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OK, it looks like there are in fact a/f ratio meters that you can just attach to your existing narrow-band o2 sensor.

http://www.amazon.com/Sunpro-CP7011-Sport-Electrical-Ratio/dp/B000MZV5HA/?tag=ihco-20 <-- $30

I'm not 100% sure if it's compatible with the o2 sensors on a 3fe. But it kinda looks that way. And if the 3FE diagnostic connector is like the 93-94 diagnostic connector, you can get the o2 sensor signal at the diagnostic connector rather than cutting into the wire harness.
 
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red hot metal:
I just googled "Glowing metal" and got the following:
C F Color
400 752 Red heat, visible in the dark
474 885 Red heat, visible in the twilight
525 975 Red heat, visible in the daylight
581 1077 Red heat, visible in the sunlight
700 1292 Dark red
800 1472 Dull cherry-red
900 1652 Cherry-red
1000 1832 Bright cherry-red
1100 2012 Orange-red

I'll keep an eye on the exhaust manifold temperature. I would assume after you drive for 1/2 hour and leave it running to check you should get a pretty good reading. 400C/750F is too hot, so I'd guess around 300F would be okay, right?

Resetting ECU:
I didn't do this after tweaking the AFM. Like I had said, the low idle is a perfectly smooth 650RPM. Today I noticed the high idle seems a bit hight at 1000 to 1200 RPM and seems a bit out of whack. I drove to work this morning, 1-1/2 miles, when parked at work it was around 1200 RPM and started to come down, then would rev back up, did this a few times then I went into work. I really don't care as long as low idle is good. Back to reset of ECU, I'm afraid to reset it and screw something up, will it? If the ECU is collecting "good running" data now will resetting it give the ECU "bad running" data? Am I over-thinking as usual?
 
ok, i ordered a cheap a/f gauge and holder. IT's coming from china so it will take a couple weeks probably.

I'd like to see about this mod on my 1fz, but I'm too big of a nerd to do it blind.
 
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