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Unread 07-25-2013, 01:38 PM   #1
dinorigginwj
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4.7L WJ misfire/coolant leak

Ok So I have a 2001 WJ 4.7L, long story short, I just got this jeep from my parents and it has over 200,000 miles on it. Engine was replaced at 130K with a 60K used motor. So the current motor has roughly 130K on it. The issue I'm having is a strange chugging/misfire. While my dad had it his mechanic chased it for a long time (new plugs, coil, injector) to no avail. Basically the guy gave up and said it's probably a pinched wire somewhere causing the misfire. Well....I've been looking at it and noticed it's losing coolant (I assume it has a heater core leak because you can smell strong coolant odor with HVAC blower on). But the strange part is when you top off the coolant the engine starts missing badly. But as the coolant level goes down and the "coolant low" notification comes on and the engine seems to run much better. Some days it has extended crank trying to start if it's sat for a few days. It does NOT overheat. It has codes for o2 sensor but other than that I'm kind of wondering if there may be a head gasket issue? possible coolant leaking into a cylinder causing the misfire and the extended crank sometimes? Any input?

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Unread 07-27-2013, 11:24 PM   #2
dinorigginwj
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Quote:
Originally Posted by dinorigginwj
Ok So I have a 2001 WJ 4.7L, long story short, I just got this jeep from my parents and it has over 200,000 miles on it. Engine was replaced at 130K with a 60K used motor. So the current motor has roughly 130K on it. The issue I'm having is a strange chugging/misfire. While my dad had it his mechanic chased it for a long time (new plugs, coil, injector) to no avail. Basically the guy gave up and said it's probably a pinched wire somewhere causing the misfire. Well....I've been looking at it and noticed it's losing coolant (I assume it has a heater core leak because you can smell strong coolant odor with HVAC blower on). But the strange part is when you top off the coolant the engine starts missing badly. But as the coolant level goes down and the "coolant low" notification comes on and the engine seems to run much better. Some days it has extended crank trying to start if it's sat for a few days. It does NOT overheat. It has codes for o2 sensor but other than that I'm kind of wondering if there may be a head gasket issue? possible coolant leaking into a cylinder causing the misfire and the extended crank sometimes? Any input?
Anybody?
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Unread 07-28-2013, 10:27 AM   #3
jokerchief462
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Nice way to put it together. If the coolant leak is the heater core I would think the coolant may be getting a wire harness in the dad wet which points to the computer causing the misfire nobody can find. Fix the heater core and see if that fixes both.

My YJ ecu harness is in the dash next to the heater assembly and heater core so you idea is spot on.
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Unread 07-28-2013, 07:59 PM   #4
dinorigginwj
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Thanks joker, I think I'll just do that, I have blend door issues also so might as well do it...
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Unread 03-23-2014, 04:01 PM   #5
dinorigginwj
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Replaced o2 sensor, huge improvement. Working on coolant leaks now.
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