JamesHigdon Posted December 5, 2012 Author Report Share Posted December 5, 2012 Does that thing have a dist style pickup ( little sensor that bolts into where the dist would go?) or does it rely off of the flex plate to determine firing times? If it is the flying magnet type I have seen chryslers run funny when the motor has been pulled and the sensor in the bell housing not being installed properly. They have a real good tendency to be pinched back there as well. Also does it miss more when it hot? It has both, the cam position sensor is mounted on what they call a "camshaft synchronizer"...a hacked off distributor with a sensor attached to it. It has the crank sensor in the bell housing, we pulled that and found some marking on the pickup of the old one and replaced it to no effect. The motor has been pulled sometime prior to all this but short of the wrong flex-plate being installed I'm not sure what it could be in there? As far as the missing, I haven't noticed it missing any more or less when hot or cold. It seems to be pretty much like clock-work all the time below 1000rpm. Link to comment Share on other sites More sharing options...
JamesHigdon Posted December 5, 2012 Author Report Share Posted December 5, 2012 i have owned my 01 jeep 4.0 for five years .and it has always had a tiny little misfire feeling under 1k ..always seems like the iac is out of wack ..have at times idle problems but goes away in a day or two ..i gave up trying to fix that problem ......i have noticed other 01 and up 4.0 having the same problems and everyone like me gave up after spending time and money .....other than the idle problem and the misfire feeling ..they all run great ..yeah may not ever solve the problem . I thought that it could be what we call 4.3L syndrome...those hunks of crap ALWAYS shake at idle, but when comparing it to my sister's 01 Grand Cherokee there is a noticeable difference. Oddly enough the truck DID seem to run better with the NGK plugs the dealer put in there...we may be trying the hottest set of NGK V-Powers we can get tomorrow to see if that makes a difference...beyond that the fuel rail is off to test the injector spray. Link to comment Share on other sites More sharing options...
KISS_Racing Posted December 6, 2012 Report Share Posted December 6, 2012 i have owned my 01 jeep 4.0 for five years .and it has always had a tiny little misfire feeling under 1k ..always seems like the iac is out of wack ..have at times idle problems but goes away in a day or two ..i gave up trying to fix that problem ......i have noticed other 01 and up 4.0 having the same problems and everyone like me gave up after spending time and money .....other than the idle problem and the misfire feeling ..they all run great ..yeah may not ever solve the problem . I thought that it could be what we call 4.3L syndrome...those hunks of crap ALWAYS shake at idle, but when comparing it to my sister's 01 Grand Cherokee there is a noticeable difference. Oddly enough the truck DID seem to run better with the NGK plugs the dealer put in there...we may be trying the hottest set of NGK V-Powers we can get tomorrow to see if that makes a difference...beyond that the fuel rail is off to test the injector spray. Do You all have a flow table? I know sometimes injectors appear to flow the same yet don't. I think I remember You saying in one of the posts You were thinking the injector might be leaking which would show on the table. I have a great contact in San Antonio if You need the injectors checked if You don't have that covered already. I'm with You on wet plug. Low to No spark which You can check temp on exhaust manifold to see difference in temp or leaking injector. The tip may have junk in it keep it. I have watch them drip to pee when they are not supposed to be sprayiing. Clean and rebuild them then no problem. Of course this is only my guess. Link to comment Share on other sites More sharing options...
JamesHigdon Posted December 6, 2012 Author Report Share Posted December 6, 2012 Do You all have a flow table? I know sometimes injectors appear to flow the same yet don't. I think I remember You saying in one of the posts You were thinking the injector might be leaking which would show on the table. I have a great contact in San Antonio if You need the injectors checked if You don't have that covered already. I'm with You on wet plug. Low to No spark which You can check temp on exhaust manifold to see difference in temp or leaking injector. The tip may have junk in it keep it. I have watch them drip to pee when they are not supposed to be sprayiing. Clean and rebuild them then no problem. Of course this is only my guess. No flow table...this is going to sound hill-billy but I've always just held the rails level and cranked the engine to see how far they shoot and its worked SO FAR... Now, to the fun part, we got it. After all the crap and after all the non-sense we finally figured it out this morning. I couldn't sleep last night because of this deal so I go up well before first light and came up here with intentions of pulling everything apart until we found a problem. Well I got as far as pulling the head and pulling the first lifter and it finally became obvious, this thing STILL has flat tappet lifters. Being Chevy/Ford guys everyone assumed the motor had roller lifters and those are OBVIOUS...hell even the dealership didn't check for a bad lifter, well Chrysler used flat tappet lifters well into this millenia and on number six the intake-side lifter had roughly a .2" dish in it. It would build compression because the valve was still opening and closing but at idle the intake valve wasn't staying open long enough to let enough fuel in for it to ignite. We've got a Ford Certified Master Tech that started for us last Monday and he was near to tears with this thing, not used to HAVING to figure out the issue because you don't have any other choice! Link to comment Share on other sites More sharing options...
jwmbishop Posted December 6, 2012 Report Share Posted December 6, 2012 Hmmm - so add into the mental toolbox throwing a dial indicator on the bad cylinder's valves and comparing actual travel to a good cylinder - before teardown... of course now cam and lifters - that lobe is probably just as shot as the lifter if not more! Link to comment Share on other sites More sharing options...
4cylfordz Posted December 6, 2012 Report Share Posted December 6, 2012 Chalk another one up to zinc free oil and an not enough lube on cam break in. Glad ya figured it out and good luck pulling that 4ft long cam outta there. Link to comment Share on other sites More sharing options...
HiTech Posted December 6, 2012 Report Share Posted December 6, 2012 WELL HECK I WAS GOING TO MENTION POSSIBLY VALVE SPRING PROBLEM ..ITS SOMETHING SYMPLE EVERY TIME .. Link to comment Share on other sites More sharing options...
JamesHigdon Posted December 6, 2012 Author Report Share Posted December 6, 2012 Hmmm - so add into the mental toolbox throwing a dial indicator on the bad cylinder's valves and comparing actual travel to a good cylinder - before teardown... of course now cam and lifters - that lobe is probably just as shot as the lifter if not more! The cam and lifter are both flat done. The really silly thing about this is we tried to test it here a month ago but the back two cylinders are under the cowl so you can't get a dial indicator in there and I haven't heard of a manufacturer using a flat tappet cam since the early 90's so we never went back to check it...then when I asked about it the dealer told us it wasn't possible but that they had tested for it anyways and the cam was fine! On a flat-tappet motor we usually check cams second or third, not a month and half into the deal! I guess Chrysler's pre-historic technology strikes again... Link to comment Share on other sites More sharing options...
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