The Dreaded Idle Mystery, Idle Me This |
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The Dreaded Idle Mystery, Idle Me This |
Apexster |
Jan 2 2020, 03:05 PM
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#1
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Newbie Group: Members Posts: 8 Joined: 1-June 18 From: Concord, CA Member No.: 22,180 Region Association: Northern California |
Looking for a little insight on the dreaded idle mysteries of a 1974 2.0 914. I've searched the archives for a couple months and tried just about everything.
Valves freshly adjusted. Compression is above 135psi and within 2% on all cylinders. Original D-jet intact with new hoses and all components tested and working. Fuel pressure tested (30-31psi from original 3 hose fuel pump). New plug wires, newly rebuilt distributor, recent fuel filter. I'm about to replace the 20 year old CHT sensor as well. The car revs smoothly and pulls very strong. Engine runs great anywhere above 1200 rpm. Problem is 3 or so minutes after a cold start it drops off the high idle and transitions to a rough idle, like it's running on three cylinders. When I spray carb cleaner in the air cleaner the idle smooths out immediately. Has anyone else come across this issue and perhaps suggest a plan of action to resolve it? (IMG:style_emoticons/default/confused24.gif) Thanks and Happy New Year to All. |
rjames |
Jan 4 2020, 04:26 AM
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#2
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I'm made of metal Group: Members Posts: 3,950 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
If the MPS has been rebuilt you absolutely need to calibrate it for your car. I’d bet a few bucks that it’s causing your lean condition especially since the issue started after rebuilding it.
And have you verified yet if the vacuum canister on the distributor holds vacuum? |
Apexster |
Jan 4 2020, 12:18 PM
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#3
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Newbie Group: Members Posts: 8 Joined: 1-June 18 From: Concord, CA Member No.: 22,180 Region Association: Northern California |
If the MPS has been rebuilt you absolutely need to calibrate it for your car. I’d bet a few bucks that it’s causing your lean condition especially since the issue started after rebuilding it. And have you verified yet if the vacuum canister on the distributor holds vacuum? Vacuum canister was verified prior to sending the distributor out for a professional rebuild (and full test set up on a Sun distributor tester). I was operating under the assumption that the MPS is a sealed unit. Thanks for that heads up. This morning I jumped on Paul Anders MPS page. I have a feeling you're right about that. After that I'll clean the injectors just for good measure. |
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