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Registered User
Join Date: Jul 2014
Location: Beaverton Oregon
Posts: 3
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Spark on 1 and 4 only
I installed a new head with new tensioner etc. on a 1987 Porsche 944S 16 valve. I replaced the cap, rotor, plugs, and wires. It starts but fires on cylinders 1 and 4 only. The Hall Sender wire connector from the distributor backing plate crumbled so I wired it with wire connectors. Can some one offer a solution for my dilemma? and help me get it running on all 4. Thanks.
I checked the injector Harness with Noid Lites. Cylinder 2 has no lite from the Noid and intermittent spark from the spark plug wire. Cylinder 3 has light from the Noid but no spark on the plug wire. Compression test: 1 @ 187, 2 @ 210, 3 @190, 4 @ 187. timing fly-wheel mark lines up with Cam mark. Last edited by Pumbaa; 07-27-2014 at 08:01 PM.. Reason: spark is on 1 and 4 not 2 and 3 |
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07-26-2014, 01:31 PM
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Automotive Necromancer
Join Date: Nov 2006
Location: Beantown, MA
Posts: 1,544
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partial spark
Hello, first of all check that connection again.
next, double check that the misfire is lack of spark and not lack of fuel injector signal as the fuel injection harness is prone to bad connections when major engine work is performed. I suggest a noid for the injector signal and a visual check for the spark on the affected cylinders. Ohm out the plug wires and check cap and rotor. IF that still hasn't gotten all your cylinders back online, compression test the engine and double check the cam timing. Basics are compression, fuel and spark, one of them is lacking. Zundefolg ist 1342. ya?
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix. |
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07-26-2014, 01:46 PM
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Registered User
Join Date: Jul 2014
Location: Beaverton Oregon
Posts: 3
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I checked the injector Harness with Noid Lites. Cylinder 2 has no lite from the Noid and intermittent spark from the spark plug wire. Cylinder 3 has light from the Noid but no spark on the plug wire. Compression test: 1 @ 187, 2 @ 210, 3 @190, 4 @ 187. timing fly-wheel mark lines up with Cam mark. any suggestions on what it might be. I am checking the connections now.
Last edited by Pumbaa; 07-27-2014 at 08:03 PM.. Reason: add more info |
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07-27-2014, 12:03 PM
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Automotive Necromancer
Join Date: Nov 2006
Location: Beantown, MA
Posts: 1,544
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getting tricky
ok, it gets tricky from here so bear with me. you should pin out (check continuity) to the injectors from the dme side. if 2 isn't getting injct signal it may be the crimp connectors that are in the injector harness. You might need to go into the inj harness and soldier some wiring. If one connection is bad, can the others be far behind? The injectors fire simultaneously but are wired to the dme in pairs. the compression seems fine and cam timing is good. You also might want to check the connector to the speed and ref sensors and check their resistance values a well. the Ref sensors are a bear to deal with should one of them turn out to be bad.
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix. |
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07-30-2014, 02:48 PM
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