 The Dreaded Idle Mystery, Idle Me This |
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| 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. |
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| Olympic 914 |
Jan 2 2020, 03:59 PM
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#2
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Group: Members Posts: 1,675 Joined: 7-July 11 From: Pittsburgh PA Member No.: 13,287 Region Association: North East States 
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| JawjaPorsche |
Jan 2 2020, 04:34 PM
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#3
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Advanced Member Group: Members Posts: 3,463 Joined: 23-July 11 From: Clayton, Georgia Member No.: 13,351 Region Association: South East States |
QUOTE(Olympic 914 @ Jan 2 2020, 04:59 PM)  (IMG:style_emoticons/default/agree.gif) I got a spacer two months ago along with a new CHT and it solved a lot of similar problems. |
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| Not_A_Six |
Jan 2 2020, 06:51 PM
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#4
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Member Group: Members Posts: 110 Joined: 28-November 18 From: North Idaho Member No.: 22,682 Region Association: Pacific Northwest
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QUOTE(JawjaPorsche @ Jan 2 2020, 02:34 PM) QUOTE(Olympic 914 @ Jan 2 2020, 04:59 PM) (IMG:style_emoticons/default/agree.gif) I got a spacer two months ago along with a new CHT and it solved a lot of similar problems. I've got a spacer, but haven't installed it yet because I also have the dreaded "warm start" issue where, after parking for 10 or so minutes, the heads have cooled but the rest of the engine is still warm. In this mode, D-Jet over-richens the mixture based on the CHT reading and it's hard to start and idles poorly for a few minutes until the heads warm back up. I'd guess that the CHT spacer might worsen the warm-start problem by making the heads appear even cooler when the block is still warm and/or delay the sensed head temp coming back up. What have you experienced with yours? |
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Posts in this topic
Apexster The Dreaded Idle Mystery Jan 2 2020, 03:05 PM
Tdskip AAR? Jan 2 2020, 03:35 PM GregAmy Does it ever smooth out after warm-up? If so, coul... Jan 2 2020, 03:48 PM
Apexster
Does it ever smooth out after warm-up? If so, cou... Jan 2 2020, 07:53 PM Apexster
[quote name='JawjaPorsche' post='2774198' date='J... Jan 2 2020, 08:05 PM GregAmy About a year ago the car developed a bit of warm i... Jan 3 2020, 05:58 AM Rand I appreciate Brad as much as we all do.
Spacers t... Jan 2 2020, 07:06 PM rjames
I appreciate Brad as much as we all do.
Spacers ... Jan 3 2020, 12:57 AM Apexster
I appreciate Brad as much as we all do.
Spacers... Jan 3 2020, 08:24 PM porschetub
I appreciate Brad as much as we all do.
Spacers ... Jan 5 2020, 04:03 PM porschetub [quote name='Apexster' date='Jan 3 202... Jan 2 2020, 08:13 PM rjames
Just re-read the above from your first post- Doe... Jan 3 2020, 01:06 AM rjames If the MPS has been rebuilt you absolutely need to... Jan 4 2020, 04:26 AM Apexster
If the MPS has been rebuilt you absolutely need t... Jan 4 2020, 12:18 PM rjames
[quote name='rjames' post='2774549' date='Jan 4 2... Jan 4 2020, 04:11 PM Apexster
[quote name='rjames' post='2774549' date='Jan 4 ... Jan 5 2020, 12:23 PM JawjaPorsche I replaced my injection wiring harness with a new ... Jan 4 2020, 06:45 AM Bleyseng Did you adjust the idle mixture after the engine w... Jan 4 2020, 12:57 PM JeffBowlsby The MPS is the primary fuel injection sensor to de... Jan 5 2020, 12:53 PM Apexster
The MPS is the primary fuel injection sensor to d... Jan 5 2020, 08:14 PM Bleyseng Vacuum is what controls the MPS so if you have any... Jan 5 2020, 01:55 PM Bucci I sent out the factory ECU brain and had all the c... Jan 9 2020, 08:19 PM Robson51
I sent out the factory ECU brain and had all the ... Jan 9 2020, 08:31 PM |
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