2001 Sport Misfire Cyl 6 still w/ New Head - Page 2 - Jeep Cherokee Forum

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2001 Sport Misfire Cyl 6 still w/ New Head

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Old 01-16-2018, 10:56 PM
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Originally Posted by extrashaky View Post
In a pinch you can also use good old copper Champion RC12ECC plugs, and that's actually the recommended plug for '99 and down.
Oh boy....
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Old 01-17-2018, 01:46 AM
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Originally Posted by PatHenry View Post
On the pre-99's what is considered the best plug? NGK or something else?
Champion coppers are the go-to. NGK should also work just fine.

Originally Posted by Matthew Price View Post
Oh boy....
Problem?
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Old 01-17-2018, 02:04 AM
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Originally Posted by Matthew Price View Post
Do you have that measurement handy? That’s an easy check I can do before the weekend. Do you remember how much that mopar sensor set you back?
Here is the CPS test procedure;

https://www.cherokeeforum.com/f51/testing-cps-5563/


I got lucky and found a good deal on my CPS on eBay, I think it was only $45 or so at the time, when most other places wanted $70 or so for a genuine MOPAR one, I got lucky though.

In a pinch, I had read about Napa sensors working well and you would get a local warranty (I think they probably have lifetime warranty on their sensors)


EDIT:
For an 00/01 Cherokee, keep it to NGK plugs, no reason to get anything else unless you 100% have a bad spark plug
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Old 01-17-2018, 08:14 AM
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Originally Posted by extrashaky View Post
Problem?
Sorry, being sarcastic since the answer to the question was already said
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Old 01-18-2018, 06:09 PM
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Update: I tested the CPS as per the link investinwaffles shared, all good on that front. I ohmed out each injector and got 12-14 for each. I haven't had time to hit up the parts store for a NOID light yet, but I swapped the injectors around and no change. I did however notice I the engine was running and I unplugged injector 5, the engine would bog, then recover when I plugged it back in (makes sense). When I tried this on injector 6, no change. I think this is a pretty solid lead. Ill install the new harness that wesleys sent when it arrives and hopefully that fixes the problems. A good tuneup, new vac lines, and the timing check are all still things that need to be done soon.
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Old 01-19-2018, 09:19 PM
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Originally Posted by Matthew Price View Post
Update: I tested the CPS as per the link investinwaffles shared, all good on that front. I ohmed out each injector and got 12-14 for each. I haven't had time to hit up the parts store for a NOID light yet, but I swapped the injectors around and no change. I did however notice I the engine was running and I unplugged injector 5, the engine would bog, then recover when I plugged it back in (makes sense). When I tried this on injector 6, no change. I think this is a pretty solid lead. Ill install the new harness that wesleys sent when it arrives and hopefully that fixes the problems. A good tuneup, new vac lines, and the timing check are all still things that need to be done soon.
USPS says it should arrive tomorrow. Id recommend using heat shrink butt connectors but I threw in two normal ones just in case you didnít have any. My large baggie of them were at another shop Iím working at. When you cut the wire back I would put the splices in the main harness run.
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Old 01-20-2018, 12:39 AM
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Originally Posted by Matthew Price View Post
Update: I tested the CPS as per the link investinwaffles shared, all good on that front. I ohmed out each injector and got 12-14 for each. I haven't had time to hit up the parts store for a NOID light yet, but I swapped the injectors around and no change. I did however notice I the engine was running and I unplugged injector 5, the engine would bog, then recover when I plugged it back in (makes sense). When I tried this on injector 6, no change. I think this is a pretty solid lead. Ill install the new harness that wesleys sent when it arrives and hopefully that fixes the problems. A good tuneup, new vac lines, and the timing check are all still things that need to be done soon.
If you are unplugging injector #6 and there is no change in the misfire, then you can be 100% sure the issue is with fuel injection on #6. Either wiring or injector itself, but you said that you changed the injector so, wiring it is.
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Old 01-20-2018, 04:14 PM
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Today I went out and did some troubleshooting. First I changed the injector harness to the one Wesleys provided, and didn't notice and discernible difference. So I swapped Spark plug #6 with #2, and didn't get anything. Next I swapped injector #6 with injector #1 ( I did test each individually on the battery and heard a definite click) the filters on each really didn't look so bad. I cleared the codes, drove a bit and got some new codes. Cylinder 6 and 2 now have misfires, and a random misfire code. I noticed the main harness' shrink wrapping is hard and brittle and most of the wires in it are soft and flimsy.

I've also noticed my oil pressure is sitting around 19-22 when hot. With the current changes my idle is a lot less rough but still feels like the engine is bogged down a little when sitting for more than a few minutes.

New hypothesis: As previously mentioned I need to trash the ACDelco 41-631s for the NGK spark plugs. I also think I need a new harness, and injectors as most of them have cracks in them.

Last edited by Matthew Price; 01-20-2018 at 04:18 PM.
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Old 01-20-2018, 05:04 PM
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Originally Posted by Matthew Price View Post
Today I went out and did some troubleshooting. First I changed the injector harness to the one Wesleys provided, and didn't notice and discernible difference. So I swapped Spark plug #6 with #2, and didn't get anything. Next I swapped injector #6 with injector #1 ( I did test each individually on the battery and heard a definite click) the filters on each really didn't look so bad. I cleared the codes, drove a bit and got some new codes. Cylinder 6 and 2 now have misfires, and a random misfire code. I noticed the main harness' shrink wrapping is hard and brittle and most of the wires in it are soft and flimsy.

I've also noticed my oil pressure is sitting around 19-22 when hot. With the current changes my idle is a lot less rough but still feels like the engine is bogged down a little when sitting for more than a few minutes.

New hypothesis: As previously mentioned I need to trash the ACDelco 41-631s for the NGK spark plugs. I also think I need a new harness, and injectors as most of them have cracks in them.
I vote crank sensor and injector sync. Also if you have had the cam sensor off it controls injector timing and needs to be fine tuned with a scanner. Toothpick will only get so accurate. Id start with injector sync.
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