Rich At Idle, Fouling Plugs

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boostedzenkii
Posts: 1
Joined: Mon Aug 24, 2015 7:39 am

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So my s13 SR20 blacktop is running extremely rich just about all the time. 5 miles down the road and the plugs will foul and come out rather wet. Studders going into boost. Sitting at 10-11 lambda at idle. Sitting at 10hg vacuum at idle. Pretty much dumping fuel in the motor when the car runs. Replaced coolant temp sensor, injectors, rail, upgraded to a tomei fpr, New maf, and New ignitor.. Can't seem to think of much else that would cause it to run so rich.


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240life
Posts: 1313
Joined: Mon Sep 24, 2007 6:02 am
Car: 1993 Coupe - S13 SR20det blacktop
Location: ME
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double check your timing and check for metered air leaking.

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lexcrob
Posts: 559
Joined: Mon Sep 22, 2008 7:38 pm
Car: I get a different ride faster than I could update this.
Location: Clarksville, TN

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Well 10hg vacuum at idle is not what id call idle. If your actually at 10-11 lambada at idle your out of your factory narrow band rand so it should be calling for fuel trims to be extremely negative. In other words your assumed stock pcm should be pulling fuel as much as it can. Since your vacuum is so "low" your ecm must think its not idling. All this could be as simple as incorrect amount of air going into the engine at idle. Numerous reasons like a stuck open fast or cold idle valve, over backed out idle speed screw, someone messed with the throttle plate stops, to say a vacuum leak at the intake gasket.

Now fouling plugs completely to where it misfires and fails to continue to run. That could be a o2 sensor that is bad. Could be oil not fuel fouling the plugs. Id be curious what your wideband reads at WOT? Will it run at Wide Open Throttle? If with at fresh set of plugs it does not pull during pedal to the floor it could be a boost leak. Ive seen a boost leak cause your problems although its normally a big one and causes stalling and other problems.

Remember base timing is directly related to base idle.
Best to start with getting idle speed right.
Also assuming your timing it correctly as described in the manual.

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lexcrob
Posts: 559
Joined: Mon Sep 22, 2008 7:38 pm
Car: I get a different ride faster than I could update this.
Location: Clarksville, TN

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Just saw the posted date. FAIL


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