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  #1  
Old 12-02-2013, 01:30 PM
zorin's Avatar
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Engine Bogs Down When Cold - Timing

When the engine temperature has not reached 85 degrees yet, it bogs down around 2000 rpm and the Economy gauge moves up to the middle. It's as if the breaks are applied or the engine is choking. The problem seems to go away when the engine reaches the operating tempurature. The fuel filter is new. last month when I checked the distributor cap and rotor, they looked as shown in attahced pictures. the cap shows sign of arching. I cleaned them and put them back. The engine seems to run fine at operating temperature.

How can I fix the arching issue? Vacuum advance? Is vacuum advance hose supposed to be connected in this engine?
Are the cap and rotor still in working condition or should I replace them?
Would this be the cause of engine bogging down when cold or should I look into some other cause?

Attached Thumbnails
Engine Bogs Down When Cold - Timing-ottawa-20131017-00221-1-.jpg   Engine Bogs Down When Cold - Timing-ottawa-20131017-00223-1-.jpg   Engine Bogs Down When Cold - Timing-ottawa-20131017-00220-1-.jpg  
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'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)
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  #2  
Old 12-02-2013, 02:46 PM
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Join Date: Feb 2011
Location: Modesto CA
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There would seem to be two issues here:
1) Cold enrichment
2) Possible timing problem

The distributor initial position is set by bringing the engine to Top Dead Center (TDC) on #1 using the mark on the harmonic dampener. When the engine is at #1 TDC the rotor should align with a mark scribed on the rim of the dist. housing.

Manifold pressure (vacuum) is supplied to the ignition control module (EZL). All timing adjustments are made in the EZL on the basis of engine speed and manifold pressure. The distributor serves only to distribute the sparks, although it does contain a centrifugal mechanism to ensure proper rotor phasing as the spark timing is advanced.

Based on the appearance of the cap and rotor replacement is in order.

With all ignition matters corrected, including the wires and spark plugs, there is still a possibility that an engine sensor is defective, causing the mixture to be lean. Sensors include water temp, air flow sensor position, over voltage protection, engine speed, road speed signal, O2 sensor, and altitude correction.
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  #3  
Old 12-02-2013, 03:52 PM
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Join Date: Feb 2003
Location: Ottawa, Canada
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Thanks Frank. Very thorough and valuable. I am going to focus on timing issue for now :
So the burn marks on distributor cap between copper contact points means that I need rotate the dirtibutor, making sure that I follow your guideline? I would like to fix the timing before I replace the cap and rotor.
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Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)
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  #4  
Old 12-02-2013, 08:35 PM
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Join Date: Feb 2003
Location: Ottawa, Canada
Posts: 126
I noticed that I am missing one of the springs in the ignition distributor! Wouldn't this affect the advance? Where can I get the missing spring?
Attached Thumbnails
Engine Bogs Down When Cold - Timing-420seldistributor.jpg  

__________________
Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)
Reply With Quote
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