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LH 2.2 MAF/CO adjustment LED (85-86 US)

 
Old 01-18-2008, 06:16 PM
  #16  
PorKen
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Hooked it up to a gas analyser at the tailpipe (no cats).

HC = 125
CO = .60

Oregon standard is HC 220, CO 1.0, at idle, so it would pass the test, but not the visual (check for cats only, hood closed).

When I first bought the car, I took it in, as is to see where it was at, and it got, with cats, HC 17, CO 0.0000.
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Old 01-18-2008, 06:47 PM
  #17  
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Oddly, the emissions sticker on the hood specifies 0.6 ▒0.2, with the O2 sensor disconnected. When I disconnected the O2 sensor, HC and CO went way up.
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Old 01-19-2008, 06:19 AM
  #18  
John Speake
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My preferred method would be to adjust CO pot with O2 sensor disconnected. With the sensor disconnected the LH defaults to mid range of the O2 loop.

Then reconnect the O2 sensor. The LED may be introducing some offset due to its threshold voltage drop ? So the correct flashing cycle may be more asymetric....

The O2 loop has a reasonably wide range, so some offset is tolerable but best not to use up more of that latitiude than necessary.
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Old 01-22-2008, 01:05 AM
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Adam Geist
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Ken,

How old is the 02 sensor? I had difficulty passing NJ emissions last year after passing a couple of years earlier. A new O2 sensor was the fix - CO was back down to 0.00% and idle/driveability improved. Before you adjust the pot on the MAF, check the O2 readings.
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Old 01-22-2008, 01:15 AM
  #20  
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Adam,

The O2 sensor is newish. With the cats installed, I'm sure the readings would be zero CO.

The LED is the O2 reading, processed by the LH. With the MAF set for an even flash, the CO is at the factory standard, pre-cat.
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Old 01-22-2008, 06:12 AM
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What was CO with O2 loop disconnected ?
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Old 02-05-2008, 09:51 PM
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I'm wondering if you could use an A/F meter which I just installed to indicate a mid range condition?
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Old 02-06-2008, 12:24 PM
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Putting the intake back together found the Maf set for 220 ohm's I reset it to 300 ohms.
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Old 02-06-2008, 12:57 PM
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I have the 84 S2 4.7 LH. With no oxygen sensors or cats. Would this procedure be used for my model as well?

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84 928S2 Euro twin distributor monster

Last edited by Big AL in VA; 02-06-2008 at 05:24 PM. Reason: changed model year from 82 to 84...typo
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Old 02-06-2008, 01:18 PM
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Originally Posted by high-brass View Post
I have the 82 S2 4.7 LH. With no oxygen sensors or cats. Would this procedure be used for my model as well?

Big AL in VA
84 928S2 Euro twin distributor monster
It's simpler on your car. Just set idle CO to 1% at the tail pipe with the pot on the MAF (3mm hex adjuster, reached with a long extension under the runners)

The set idle speed to 675rpm with the adjuster on the throtlle assembley, just under the tie bar.

If the CO won't come up as high as 1% your MAF is badly aged and should be replaced.
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Old 02-06-2008, 01:49 PM
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Originally Posted by Tampa 928s View Post
I'm wondering if you could use an A/F meter which I just installed to indicate a mid range condition?
That'd work. On my car, when it was centered, the idle control was (is) better.



Originally Posted by high-brass View Post
I have the 8{4} S2 4.7 LH. With no oxygen sensors or cats. Would this procedure be used for my model as well?
Because the euro LH2.2 doesn't have the 02 sensor, or idle control valve, it doesn't need, or have, the diagnostic connector.
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Old 02-06-2008, 03:43 PM
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ty John and Porken

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84 928S2 Euro twin distributor monster
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Old 04-08-2008, 01:41 PM
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Can I read the value of the Maf 380 Ohms off of the Lh connector pins 3 and 6?
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Old 04-08-2008, 01:46 PM
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Originally Posted by Tampa 928s View Post
Can I read the value of the Maf 380 Ohms off of the Lh connector pins 3 and 6?
No, pin 14 LH2.2 is the pot, measure wrt ground, car chassis or pin pin 11 of LH.
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Old 04-08-2008, 02:01 PM
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Is the basic setting 382 Ohms mine was set to 0 Ohms after I tried to adjust it with the OX sensor off to get it to 14.7V.
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