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Registered User
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'78 924 - rough idle - start issues
I've recently replaced the starter, alternator, capt & rotor, rebuilt the wiring harness, rewired dash, replaced air filter, change oil and filter, spark plugs (new wires on road here, thermostat and water pump).
I know its a '78, but idle is rough while idling at 900 rpm. wasn't sure if I should be checking for a vacuum issue further than listening and playing with all the hoses, or if i'm looking at an injector / fuel issue? Maybe timing? |
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05-21-2013, 12:07 PM
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Back from Beyond
Join Date: Nov 2004
Location: Alberta, Canada
Posts: 2,697
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CIS testing and tuning is an art unto itself. Eliminate all vacuum leaks - period. Check your AAV (auxiliary air valve) isn't stuck. These can be cleaned to free them up. Then you can run checks on your fuel pressures (cold and hot). One possible culprit is the warm-up regulator - these also can be cleaned/rebuilt and they get crudded up after years of use. Head on over to 924board.org as there's tons of good info there. CIS is a great system when it's sorted but a PITA getting there.
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'88 944 Auto - project, kinda '87 944 Auto - died saving my wife '84 944 5SP - crushed under shop roof during snow storm All others GONE! |
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05-21-2013, 12:31 PM
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In the Fires of Hell.....
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+1 on what Slam said.
Also, pop out your injectors, bridge the fuel pump relay and push up on the CIS air flow meter plate to check your injector spray patterns. Do this with the ignition off, or at the least without turning over the engine.
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PCA Instructor: '88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG, 3120 lbs, 256 RWHP, 15 psig boost |
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05-21-2013, 01:44 PM
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Registered User
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Gives me quite a bit to check! Thanks everyone. Now I gotta figure out what everything is lol
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05-21-2013, 03:02 PM
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Incorrigible
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Read this. If you don't understand K-Jetronic after this, read it again!
Bosch K-Jetronic Fuel Injection Manual http://www.cannell.co.uk/Bosch_Technical/Bosch_Technical_Instruction_K-Jetronic.pdf I am going through a 79 I just bought and am un screwing everything from the PO, and cleaning, and adjusting, and cleaning. I like this system and engine so much, I am actually toying with replacing my 951 with a Carerra GT clone. Well, maybe not. Maybe ADDING a CGT clone to the stable. Right. (Insert divorce here). Jeff
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1988 951 all track modded and angry, 2002 Boxster '88 924S, '65 912/911, '86 951, '79 924, '85 944 N/A, automatic - all gone. "It makes me sad. Our cars were meant to be driven, not polished" - Ferry Porsche while surveying a concours field. Last edited by ditch68; 05-21-2013 at 05:06 PM.. |
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05-21-2013, 05:02 PM
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AFM #725
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The car will last longer than your wife, Jeff. Choose wisely.
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Watchdog Armory Racing AFM #725 Thanks to my 2017 Sponsors: JPH Suspension | AXO | Armour Bodies | BELL Helmets | Braven | EVLUTION Nutrition | Forcefield Armor | FunTrackDayz | Galfer | Motion Pro | MOTUL | Matrix Racing Concepts | ODI Grips | OGIO | Shorai Inc. | SPEEDMOB | Vortex | Woodcraft | Wicked Audio http://www.gawerracing.com |
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05-21-2013, 05:31 PM
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Back from Beyond
Join Date: Nov 2004
Location: Alberta, Canada
Posts: 2,697
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Another culprit in hard starts is the fuel accumulator. It lives under the rear of the car near the tranny, after the fuel filter (if you trace the fuel line from the tank). It can fail to hold residual pressure in the lines, so every time you start the car you've gotta pressure up the system, which takes some cranking.
In my experience, changing cars is better than changing wives. It's cheaper too... Maybe I just got really lucky in the wife department.
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'88 944 Auto - project, kinda '87 944 Auto - died saving my wife '84 944 5SP - crushed under shop roof during snow storm All others GONE! |
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05-22-2013, 07:37 AM
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944 Turbo
Elsa
Elise
1983 Porsche 944
John Paul Jones
