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Golen 4.6 random misfires

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fhunziker
Posts: 4
Joined: March 25th, 2021, 11:38 am
Stroker Displacement: 4.6L
Vehicle Year: 2001
Vehicle Make: Jeep
Vehicle Model: WJ (GC)

Golen 4.6 random misfires

Post by fhunziker » April 7th, 2021, 9:19 pm

Hi All, I'm a noob to strokers and have pretty basic mechanic skills. I could really use some expert input on a persistent random misfire issue on my 2001 WJ.

I recently purchased a complete dyno'd Golen Engine 4.6 stroker with 62mm TB and headers and had it installed by my trusted mechanic. Since the installation the engine has been throwing random misfire codes P0300, P0301, P0303 when RPMs >2000, light or heavy throttle. My mechanic has done a lot of diagnostic work that I don’t have the technical knowledge to describe, but long story short the aftermarket sensors we transferred from the old engine all seemed to be operating fine. Fuel pressure is "good" and my mechanic seems certain this is a controls issue.

Based on recommendations from Golen and other Golen engine owners who had misfire issues, we’ve now replaced all of the following with new Mopar parts: cam position sensor, MAP sensor, TPS, ignition coil, all O2 sensors, O2 wiring harness, and oil pressure sender. We’ve reset the ECU, tested the new (Bosch?) fuel injectors and disconnected the PCV vent/plugged the intake manifold to see if the new valve cover was causing the issue. None of these measures have solved the problem.

We are now ordering a new (used) programmed ECU, and a used wiring harness to replace the oil-soaked harness that might be causing grounding issues. It’s my sincere hope that one of these will solve the problem as there isn’t much more we can do.

Your expert advice, dumbed down for a layperson, is welcome. Thanks in advance.

fhunziker
Posts: 4
Joined: March 25th, 2021, 11:38 am
Stroker Displacement: 4.6L
Vehicle Year: 2001
Vehicle Make: Jeep
Vehicle Model: WJ (GC)

Re: Golen 4.6 random misfires

Post by fhunziker » April 9th, 2021, 5:49 pm

Adding some additional info requested in another forum:
.
Spark plugs: installed by Golen, Champion RC9YC4 #430 gapped to .035"
Fuel injectors: from Golen, Bosch 24#
Fuel pressure: 54 psi at idle
Vacuum: new manifold is tight, 14-16 inches mercury at engine. A little low likely because it's a new engine.
Codes: P0300, P0301, P0303. Mechanic confirms it misfires across all cylinders.
Compression: 160 psi at all cylinders, no leak down test necessary.
Air bag light: none
Oil pressure: 60 psi @ 2000 RPM, 30 psi at idle
ECT: water and air temp sensors are original OEM.
MAP, TPS, pre-cat O2: no report other than just replaced with all new Mopar parts.

The ECU and wiring harness are already shipped so we'll have to see if that solves the problem. Next up I suppose is replacing the water and air temp sensors?

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Cheromaniac
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Posts: 2932
Joined: March 8th, 2008, 12:58 pm
Stroker Displacement: 4563cc
Vehicle Year: 1992
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Cyprus
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Re: Golen 4.6 random misfires

Post by Cheromaniac » April 9th, 2021, 11:21 pm

Next up you should be considering replacing coil packs rather than various sensors.
1992 XJ 4.6 Stroker - 5MT - Sold :cry: Stroker build-up, Stroker "recipes"
2006 Mustang GT - 5MT - Midlife crisis car :D with Mods

fhunziker
Posts: 4
Joined: March 25th, 2021, 11:38 am
Stroker Displacement: 4.6L
Vehicle Year: 2001
Vehicle Make: Jeep
Vehicle Model: WJ (GC)

Re: Golen 4.6 random misfires

Post by fhunziker » April 10th, 2021, 12:19 am

Coil pack was replaced with new Mopar coil pack, see OP above.

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Cheromaniac
Senior Member
Senior Member
Posts: 2932
Joined: March 8th, 2008, 12:58 pm
Stroker Displacement: 4563cc
Vehicle Year: 1992
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Cyprus
Contact:

Re: Golen 4.6 random misfires

Post by Cheromaniac » April 10th, 2021, 11:59 pm

Gotcha.
Could it be something as simple as the cam position sensor being a few degrees off?

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