AFM Adjustment

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asiab3
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Re: AFM Adjustment

Post by asiab3 » Sat Apr 16, 2016 2:59 pm

SlowLane wrote:Robbie, since you've monkeyed around with the AFM spring, and also since you're unsure about the quality of a Python unit to begin with, perhaps it might be helpful to use Steve Kent's weight-calibration method as an initial starting point.
I will check it out; though if I get an acceptable fuel map from my McGuyver PCV orifice I'm mocking up, I may be tempted to Just Drive. It might also be fun to swap in my spare AFM to compare the two maps before and after adjusting each according to the "what the engine wants" qualifications.
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Sat Apr 16, 2016 6:15 pm

asiab3 wrote:It might also be fun to swap in my spare AFM to compare the two maps before and after adjusting each according to the "what the engine wants" qualifications.
If one of the two AFMs is known untampered with, can you use that as the "control" map?

If it is a reman, we lose a little control credibility, but it would still be interesting.

I just reverted Naranja to factory spring and mixture screw, and added 1/4 wiper tooth rich. I get my lean lean idle back and better cold running, and so far, the moderate-to-full power is definitely improved.

Please note, these engines were calibrated to the very edge from the factory. They are *supposed* to be a bit annoying during cool running as in the first couple of minutes after a gas stop where the heat soak has kept the TS 2 at lean but the combustion chambers have cooled.

For me, the symtom is a little bucking at partial throttle from the gas pump island to the street, a little balky in the 2nd gear pull, and perfectly smooth by two or so traffic lights. I am leaning the idle out incrementially until I get back that beautiful original quick cold start 1,300 rpm at first minute, 1,100 rpm at third to fourth minute and that noticeable drop in idle when the AAR closes.
Colin
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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Re: AFM Adjustment

Post by fetzic » Mon May 16, 2016 5:10 pm

I am working on a 79 FI engine that had been built some time ago by a builder in LA. For many reasons to numerous to go into the engine never preformed very well so I've removed it and have attempted to run it mocked up. My only problem at this point is getting fuel past the regulator to the rail. I have two used Bosh regulators one which was installed in the car and working. Fuel pump runs and puts good pressure out, ALL vacuum connections solid,no clogged lines. My questions are: how much vacuum is required for regulator activation, can I produce sufficient by mouth and is there a way to pre-charge the fuel rail. I am able to prime the plenum and get short engine runs but not long enough to break loose the regulator. Any suggestions?

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SlowLane
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Re: AFM Adjustment

Post by SlowLane » Mon May 16, 2016 5:45 pm

fetzic wrote:My questions are: how much vacuum is required for regulator activation, can I produce sufficient by mouth
Probably not.
fetzic wrote:and is there a way to pre-charge the fuel rail.
With the ignition key at the running position, but not attempting to start the engine, manually move the AFM flap off of its resting position. This should close the switch in the AFM that energizes the fuel pump relay.

Or you could fashion a jumper like the one Colin uses on the double relay connector to energize the pump directly. Don't know offhand which pins on the connector he jumps.
fetzic wrote: Any suggestions?
Yup. Invest in a Mityvac.
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Sat May 21, 2016 5:24 am

fetzic wrote:I am working on a 79 FI engine that had been built some time ago by a builder in LA. For many reasons to numerous to go into the engine never preformed very well so I've removed it and have attempted to run it mocked up. My only problem at this point is getting fuel past the regulator to the rail. I have two used Bosh regulators one which was installed in the car and working. Fuel pump runs and puts good pressure out, ALL vacuum connections solid,no clogged lines. My questions are: how much vacuum is required for regulator activation? Any suggestions?
The regulator does not require "activation". It only reduces pressure under vacuum signal. The system should be charging the fuel rail in 2 seconds flat when the pump turns on. The regulator will open the return line at 36 psi from the pump. It will hold 14 psi at shut-off.

The pump is plumbed directly to the 3/4 rail, over to the CSV to the 1/2 rail, then to the regulator. The regulator then passes the fuel to the return. Do you, do you . . . . do you have the pump leading to the regulator?????
Colin
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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Re: AFM Adjustment

Post by fetzic » Sun May 22, 2016 12:51 pm

Thank you greatly for the prompt reply. Somewhere along the line the input and output fuel lines to the regulator were reversed. Duh! For now problem solved. Once again many thanks.

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asiab3
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Re: AFM Adjustment

Post by asiab3 » Sun May 22, 2016 4:18 pm

fetzic wrote:Thank you greatly for the prompt reply. Somewhere along the line the input and output fuel lines to the regulator were reversed. Duh! For now problem solved. Once again many thanks.
How is this possible? Wouldn't the regulator have to be installed backwards?

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Mon May 23, 2016 6:49 pm

asiab3 wrote:
fetzic wrote:Thank you greatly for the prompt reply. Somewhere along the line the input and output fuel lines to the regulator were reversed. Duh! For now problem solved. Once again many thanks.
How is this possible? Wouldn't the regulator have to be installed backwards?

Robbie
Nope. Our intrepid fetzic mechanic here, in his effort to test-stand the engine, accidentally led his fuel pump hose to the nipple on the fuel pressure regulator sticking out the front tin, and he pumped his return line to the left side fuel rail nipple.
ColinThat'sTheWayIReadItAnyway
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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Re: AFM Adjustment

Post by fetzic » Sun May 29, 2016 4:59 pm

It took effort but I managed!

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Re: AFM Adjustment

Post by fetzic » Sun May 29, 2016 5:09 pm

My ignorance is not work taking valuable cyberspace pertaining to fuel pressure regulators--next question. My 79 vert. has neither the original Motor or Trans. Motor ID not a problem. Would like to find out what the factory trans. gearing and ID numbers might or would have been. Anyone, Anyone?

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Mon May 30, 2016 6:55 pm

fetzic wrote:My ignorance is not work taking valuable cyberspace pertaining to fuel pressure regulators--next question. My 79 vert. has neither the original Motor or Trans. Motor ID not a problem. Would like to find out what the factory trans. gearing and ID numbers might or would have been. Anyone, Anyone?
Next question does not belong here in Fuel Delivery.

Try the Type 1 Forum and look for "Beetle Shift Points" sticky . . . read the link too!
Colin

viewtopic.php?f=23&t=11366#p199312
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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josebrewin
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Re: AFM Adjustment

Post by josebrewin » Mon May 30, 2016 7:14 pm

This is great stuff. I adjusted the AFM and it stays at proper readings when not in gear. (idle (1000), and 2000 RPM- 13-14afr) but goes super rich when in gear. runs at 7.4 on the freeway and in the 11s when I am driving it at 2000 rpm at 15 and 25 mph. Shouldn't work both ways?
Rene Martinez

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asiab3
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Re: AFM Adjustment

Post by asiab3 » Mon May 30, 2016 9:17 pm

josebrewin wrote:This is great stuff. I adjusted the AFM and it stays at proper readings when not in gear. (idle (1000), and 2000 RPM- 13-14afr) but goes super rich when in gear. runs at 7.4 on the freeway and in the 11s when I am driving it at 2000 rpm at 15 and 25 mph. Shouldn't work both ways?
Not always the case in gear vs. in neutral for fuel/load/AFR readings. In gear on the road, you'll need more pedal to get the same mount of RPM due to the load of actual driving.

Where are you measuring your AFR? I've never seen a wideband sensor that is capable of measuring as rich as 7.4 under continuous operation. If it's in your tailpipe, what is your tailpipe setup like?

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: AFM Adjustment

Post by josebrewin » Tue May 31, 2016 5:31 pm

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.
Rene Martinez

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Amskeptic
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Re: AFM Adjustment

Post by Amskeptic » Wed Jun 01, 2016 5:16 am

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
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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