Cracked head or injector problem?

toomanyfords · 10-02-2011, 05:40 PM

question for you guys, i've learned alot from this site but unfortunately I cannot find a complete answer for my question using the search function so any help is much appreciated. First let me tell you this is a 98 xlt 4.0 ohv. A couple months ago i started experiencing a cold start shake for about the first 15 seconds. Well thursday when I was leaving work the shake didnt stop and turned into a constant misfire and "bucking" while trying to drive home. Friday I pulled plugs and found cylinder 3 plug to be black and fouled up. compression test shows 111 on that cylinder, around 130 for the other five. leak down test showed 9% leak down on cylinder 3, air leaking through throttle body. other cylinders were less than 5% leaking through crankcase (normal in my eyes for 154,000 miles). I have been slowly losing coolant over the past few months but didn't think much of it. I do have spark and have tried swapping wires etc. No codes and for some reason my scanner is showing -100% fuel trim so it seems I can't check that. So I wanted a second opinion on this, either my head is cracked and leaking down through the intake valve, or I have an injector problem and excess carbon causing the valve to not seat. Sorry for the long post but wanted to provide details. any help is much appreciated, thanks again

toomanyfords · 10-02-2011, 06:56 PM

just wanted to also say I performed a combustion leak test through the radiator and the head gasket seems to be ok. Vacuum is also a steady 17 in. at idle regardless whether its missin or not. thanks in advance for any replies

toomanyfords · 10-03-2011, 07:19 PM

well in the event that someone is reading this thread i figured I'd post an update. just replaced the fuel injectors and re-torqued lower intake. I had the injectors sitting around, and decided why not. Well it stills runs like crap and still misses, exhaust is smoking and smells like unburned fuel. I'm about ready to take the shotgun approach and put heads on it. I have fuel, spark, and decent enough compression on all cylinders to where it shouldn't be misfiring, only thing I've found that is odd is leakdown through the throttle body on cylinder and 3 and semi-low compression, but doesn't seem like enough to create a misfire. If anybody has had any similar experiences or has any advice at all please let me know. thanks in advanced

10-02-2011, 05:40 PM	#1
toomanyfords Wannabe Elite Explorer Rockville,MD 98,93,and 91 explorers Join Date: Oct 2011 Posts: 67 Vehicle Specs (Original Poster)	Cracked head or injector problem? question for you guys, i've learned alot from this site but unfortunately I cannot find a complete answer for my question using the search function so any help is much appreciated. First let me tell you this is a 98 xlt 4.0 ohv. A couple months ago i started experiencing a cold start shake for about the first 15 seconds. Well thursday when I was leaving work the shake didnt stop and turned into a constant misfire and "bucking" while trying to drive home. Friday I pulled plugs and found cylinder 3 plug to be black and fouled up. compression test shows 111 on that cylinder, around 130 for the other five. leak down test showed 9% leak down on cylinder 3, air leaking through throttle body. other cylinders were less than 5% leaking through crankcase (normal in my eyes for 154,000 miles). I have been slowly losing coolant over the past few months but didn't think much of it. I do have spark and have tried swapping wires etc. No codes and for some reason my scanner is showing -100% fuel trim so it seems I can't check that. So I wanted a second opinion on this, either my head is cracked and leaking down through the intake valve, or I have an injector problem and excess carbon causing the valve to not seat. Sorry for the long post but wanted to provide details. any help is much appreciated, thanks again __________________ 98 xlt ohv tt&shackles/aal on 31's flowmaster delta 40, 93 xlt ohv 5 speed stock , 91 sport lift springs&aal on 31's cragar soft 8's, built engine with comp cam, smith bros pushrods, delta cam rocker arms, comp springs, headers, flowmaster delta 40

10-02-2011, 06:56 PM	#2
toomanyfords Wannabe Elite Explorer Rockville,MD 98,93,and 91 explorers Join Date: Oct 2011 Posts: 67 Vehicle Specs (Original Poster)	just wanted to also say I performed a combustion leak test through the radiator and the head gasket seems to be ok. Vacuum is also a steady 17 in. at idle regardless whether its missin or not. thanks in advance for any replies __________________ 98 xlt ohv tt&shackles/aal on 31's flowmaster delta 40, 93 xlt ohv 5 speed stock , 91 sport lift springs&aal on 31's cragar soft 8's, built engine with comp cam, smith bros pushrods, delta cam rocker arms, comp springs, headers, flowmaster delta 40

10-03-2011, 07:19 PM	#3
toomanyfords Wannabe Elite Explorer Rockville,MD 98,93,and 91 explorers Join Date: Oct 2011 Posts: 67 Vehicle Specs (Original Poster)	well in the event that someone is reading this thread i figured I'd post an update. just replaced the fuel injectors and re-torqued lower intake. I had the injectors sitting around, and decided why not. Well it stills runs like crap and still misses, exhaust is smoking and smells like unburned fuel. I'm about ready to take the shotgun approach and put heads on it. I have fuel, spark, and decent enough compression on all cylinders to where it shouldn't be misfiring, only thing I've found that is odd is leakdown through the throttle body on cylinder and 3 and semi-low compression, but doesn't seem like enough to create a misfire. If anybody has had any similar experiences or has any advice at all please let me know. thanks in advanced __________________ 98 xlt ohv tt&shackles/aal on 31's flowmaster delta 40, 93 xlt ohv 5 speed stock , 91 sport lift springs&aal on 31's cragar soft 8's, built engine with comp cam, smith bros pushrods, delta cam rocker arms, comp springs, headers, flowmaster delta 40

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