Idle Speed and Air Temp/Humidity |
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Idle Speed and Air Temp/Humidity |
StarBear |
Jun 29 2022, 12:46 PM
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#1
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Advanced Member Group: Members Posts: 2,072 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States |
As getting ready for the 2022 Northeast Gathering, I'm encountering a semi-recurring idle issue on my 1974 1.8L LJet FI. When outside air is cool and dry, idles just fine at 950-1000 rpm. When outside air is warm and humid, after warmup the idle falls off to barely running. I've just been adjusting the air flow screw (maybe 1.5-2 full turns) to open it. Of course, the reverse happens - if I preadjust the screw it idles near 1800 then settles down to 1100 after the engine gets totally warm (15 mins or so).
I presume (?) there SHOULD be some regulation, perhaps with the ECU or AFM, to monitor air temp and humidity and make adjustments automatically? I didn't have to manually do this adjustment in the past. The AAR works and tests out fine. Just annoying to have to pull over after running a while and adjust the screw. (IMG:style_emoticons/default/dry.gif) Your thoughts @Van @Van_B and @Wonkipop ? |
Van B |
Jun 29 2022, 11:24 PM
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#2
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Senior Member Group: Members Posts: 1,618 Joined: 20-October 21 From: WR, GA Member No.: 26,011 Region Association: None |
On these cars idle is far more likely to climb from metered air than any fueling change. When you mess with the AFM flapper while the car is running you can better understand how small the fuel window is for idle. A bit too little fuel, idle drops, a bit too much, idle drops.
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