AFM Adjustment

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asiab3
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Re: AFM Adjustment

Post by asiab3 » Wed Jun 01, 2016 7:23 am

Amskeptic wrote:
josebrewin wrote:The bung is just before the catalytic converter in the elbow. It is an Innovate LM-2 wide band sensor. I have an 18 foot cable that brings it into the drivers compartment and it runs on the cigarette lighter. Ordered an SD card so I can record it.
That is way rich, but if it runs / drives, I do not believe that 7.4. Are you calibrated to 20.9 in free air?
( Do you have clean air? :cyclopsani: )
Colin
Mine always calibrates to 20.9% O2 readings... Is there an acceptable tolerance for variation?

I too can't seem to drive the car if it ever dips below 10.0:1 AFR.
Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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josebrewin
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Re: AFM Adjustment

Post by josebrewin » Wed Jun 01, 2016 6:36 pm

The AFM reads 20.9 in free air. I get about 13 mpg overall, goes to 65-70 mph on freeway. It shows good at neutral and as soon as it goes in gear the mixture creeps rich. I am going to go to the gold smog place this Friday to see how far off I am. They adjusted the AFM before and it passed with a distributer that didn't advance. New distributor now advances.
Rene Martinez

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josebrewin
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Re: AFM Adjustment

Post by josebrewin » Fri Jun 03, 2016 1:15 pm

The smog Mechanic may have found the issue. My Intake sleeve has a crack- vacuum leak, I only checked the hoses for leaks. I re- checked it with starter fluid at home and had a slight rise in acceleration when spraying the right side of the sleeve. I ordered a new sleeve and am back to the drawing board.
Rene Martinez

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Re: AFM Adjustment

Post by josebrewin » Sat Jun 04, 2016 4:22 pm

I removed the intake sleeve and there was a ~ 60 degree crack along the bottom clamp. I replaced the sleeve with a new one and the AFR readings are now much better. 14.7 at idle (1000 rpm) and now at acceleration it is closer to 11 than 7.4. Now need to fine adjust at 15 and 25 mph and see if I can stay above 14 afr.
Rene Martinez

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Mon Jun 20, 2016 4:57 pm

josebrewin wrote:I removed the intake sleeve and there was a ~ 60 degree crack along the bottom clamp. I replaced the sleeve with a new one and the AFR readings are now much better. 14.7 at idle (1000 rpm) and now at acceleration it is closer to 11 than 7.4. Now need to fine adjust at 15 and 25 mph and see if I can stay above 14 afr.
Good job! Why do you want to stay above 14? That is heat-generating lean.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: AFM Adjustment

Post by josebrewin » Tue Jun 28, 2016 9:43 pm

I was just trying it out at smog pass level. Should I run at 13? I am taking it camping this weekend. The alternator ended up needing replacing (12 volts max running and 11Volts with the lights on). Was working on the mustang the last few weeks. Vac leak and replaced drive shaft. Much better now
Rene Martinez

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Re: AFM Adjustment

Post by josebrewin » Sun Jul 03, 2016 4:28 pm

I changed AFM to about 11 and it ran about 10 degrees cooler at the same MPG (~ 13mpg HWY). It felt like it had a little more power also. Leaving it there for now.
Rene Martinez

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Mon Jul 04, 2016 5:55 am

josebrewin wrote:I changed AFM to about 11 and it ran about 10 degrees cooler at the same MPG (~ 13mpg HWY). It felt like it had a little more power also. Leaving it there for now.

Seems counter-intuitive, but I had the same results with my 1978 bus.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: AFM Adjustment

Post by DugB » Thu Apr 12, 2018 10:01 am

Colin, you piqued my interest in the AFM during your last visit to my place in Falls Church, VA, and because of all of your info at the top of this thread I had the guts to get into mine yesterday. I was pleased to see very intact wiper tracks and a clean interior. I wanted to decrease CHTs a bit when running at higher speeds/loads for sustained periods...just cruising at 65 I'd be pushing 400 degrees with AFR readings around 13.1 (I don't have an Innovate AFR, but rather the one from PLX Devices on which I only ever see ranges from 12 to 13.5, though the engine runs great).

I moved the cog wheel two notches richer, and saw the AFR readings drop by about 0.2 - 0.3 on average. It did result in a bit of a CHT temp drop (maybe 30 degrees on average at highway speeds/loads), with no noticeable impact to performance. I'll run this for a bit, and then try the plug chop some night when I have time. I'm contemplating one more notch richer, just to try it out.

Thanks again!

- Doug

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Re: AFM Adjustment

Post by Amskeptic » Mon Apr 16, 2018 8:19 am

DugB wrote:
Thu Apr 12, 2018 10:01 am
Colin, you piqued my interest in the AFM during your last visit to my place in Falls Church, VA, and because of all of your info at the top of this thread I had the guts to get into mine yesterday. I was pleased to see very intact wiper tracks and a clean interior. I wanted to decrease CHTs a bit when running at higher speeds/loads for sustained periods...just cruising at 65 I'd be pushing 400 degrees with AFR readings around 13.1 (I don't have an Innovate AFR, but rather the one from PLX Devices on which I only ever see ranges from 12 to 13.5, though the engine runs great).

I moved the cog wheel two notches richer, and saw the AFR readings drop by about 0.2 - 0.3 on average. It did result in a bit of a CHT temp drop (maybe 30 degrees on average at highway speeds/loads), with no noticeable impact to performance. I'll run this for a bit, and then try the plug chop some night when I have time. I'm contemplating one more notch richer, just to try it out.

Thanks again!

- Doug
How do you like your PLX a/f reader?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: AFM Adjustment

Post by DugB » Mon Apr 16, 2018 8:27 am

Well, because everyone seems to be using the Innovate meter, and the PLX figures for comparison don't seem to be in the same ballpark, I just ordered an LC-2 to install. Now that I've been into the AFM, and understand the adjustments possible a bit more due to this (and other) threads, I want numbers I can actually compare with others.

As for the PLX all by itself, it has not been trouble-free. There have been long periods of time where the meter seemed to still be working (due to the colored lights still responding), but the center section would not show the AFR reading value after the start up sequence. There is no data output, so I can't do anything with the data being generated. The installation also doesn't seem as easy as the LC-2, either. That said, I have never experienced the O sensor woes that some LM-1/LM-2/LC-1/LC-2 customers have reported.

I'll let you know more fully after I have a chance to install the LC-2. :-)

- Doug

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Re: AFM Adjustment

Post by Blue Moose » Tue Jun 12, 2018 8:48 am

'83 Westy Fuel Injection idle adjustment

I'm new to the forum, but have really gotten a lot out of the info here. I want to start by saying thank you all!

I have an LM-2, and have found that when the idle is "best" the AFR is about 12.5. In my mind, it should run best at stoichiometric (14.7). Which of my assumptions is wrong here?

If I lean it out (as recommended), I can get it down to 14.2, but it is not very "happy" at this mixture, and develops a "lope," where the RPM and AFR cycle up and down. It's definitely running lean, but I'm not sure why it is loping. The idle mixture can be adjusted somewhat with the first dozen turns of the idle adjustment screw. After about a dozen it doesn't seem to have any effect.

I haven't found any vacuum leaks yet (still need to check the brake assist), timing is set to about 28.5 BTC @ high revs with the advance hose disconnected (although I have a hard time trusting that plastic timing gauge) and 7.5 with the hose hooked up and at idle. This is a standard 2.0 engine with hydraulic lifters. The only non-stock item I'm aware of is removal and capping of the EGR.

All of this was instigated by Oregon DEQ, which does an idle-only test requiring CO to be less than 1% (which seems pretty low!). Most importantly though, I want it to run right!

(If I should be posting elsewhere, please let me know. I'm new to using forums in general, so thanks in advance!)

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Tue Jun 12, 2018 9:07 am

Blue Moose wrote:
Tue Jun 12, 2018 8:48 am

have found that when the idle is "best" the AFR is about 12.5.
In my mind, it should run best at stoichiometric (14.7).
Which of my assumptions is wrong here?

All of this was instigated by Oregon DEQ, which does an idle-only test requiring CO to be less than 1% (which seems pretty low!).
Stochiometric is the **most efficient complete burn** of the fuel charge. That is less than the **best combustion hit against the poor pistons**.

Vanagons typically have horribly weak lopy idles at .7% CO at stochiometric. Not a big deal, so long as the engine gets a nice cool rich mixture out on the road.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

DugB
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Re: AFM Adjustment

Post by DugB » Tue Jun 12, 2018 11:12 am

Wait, on these meters is a lower number leaner, or a higher number I thought higher.

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Re: AFM Adjustment

Post by DugB » Tue Jun 12, 2018 11:17 am

From Turbo by Garret:
“So what is meant by a rich or lean AFR? A lower AFR number contains less air than the 14.7:1 stoichiometric AFR, therefore it is a richer mixture. Conversely, a higher AFR number contains more air and therefore it is a leaner mixture. Leaner AFR results in higher temperatures as the mixture is combusted.”

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