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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Brought it home and got it "running" the next day. It had multiple breaks in the engine harness and blown fuses for O2, PCM, and Fuel Pump. I "fixed" those breaks, replaced the fuses, and it start right up...however it ran like garbage, multiple misses, stumbling on any amount of throttle application, backfires...you name it. So I went to town checking things. Over the next few days I double checked that the wires were hooked up correctly and in good shape, set the ignition properly making sure to set the Cam Position Sensor correctly, and just generally checked over the ignition.
Still ran the same way, no change. So I started unplugging injectors just to see what cylinders would affect the run condition. Every cylinder had an affect at idle but #6, so then I went to compression check it.
Cyl #6 after cranking about 4-5 times
Cyl #1-#5 after cranking about 4-5 times
So...need some opinions. I'm thinking stuck valve-train, and I'll move onto that next for inspection. If it's not that, and you have some other path for me to dive down I'd love to hear it.
Due to the harness issues, broken bolts all over the motor and chassis, evidence of excessive amounts of water inside the cab, cancer on the passenger floor and part of the roof, along with a few other issues I've already bought a much cleaner 2wd XJ to transfer the usable parts to but...I'm hesitating.
Would like some input on this issue before I commit.
I'd pop the valve cover off and see what's going on. Crank it and watch it. Maybe give the valves/springs the ol rubber hammer test.
The other advice I've gotten is to run some seafoam through the intake and see if something lets lose. Was told it could be excessive oil/carbon build up. Obviously Seafoam isn't some fix all but it I feel like it's worth a try, and in the end if that frees things up I'll need to figure out why it was an issue to start with.
Yeah, looks wet. So if there's fuel or oil in it, that would raise the compression. You can try cranking the engine with the plugs out, wide open throttle and see if anything blows out the spark plug hole in #6. Pull the fuel pump relay to prevent any fuel from injecting.
Yeah, looks wet. So if there's fuel or oil in it, that would raise the compression. You can try cranking the engine with the plugs out, wide open throttle and see if anything blows out the spark plug hole in #6. Pull the fuel pump relay to prevent any fuel from injecting.
All plugs were out for the compression test, so it had plenty of chances to blow something out but I can try again with the steps you've mentioned.
The other advice I've gotten is to run some seafoam through the intake and see if something lets lose. Was told it could be excessive oil/carbon build up. Obviously Seafoam isn't some fix all but it I feel like it's worth a try, and in the end if that frees things up I'll need to figure out why it was an issue to start with.
Watch some videos of how to Seafoam through a vacume line. Engine has to be up to temperature first. Do it somewheres where your neighbors won't see the black cloud that comes out of the tail pipe.
I run a stroker and all my cyls run at 180..all fire off with the normal spark source...hook the plug wire up to a spare plug and ground the threaded section to the block or battery neg with an alligator clip..have someone crank or let it run if possible...you will know in a few seconds if your sparking on nbr 6..to get to 180 or any normalish number the intake has to open to let in air. If the exh does not open, that might allow you to build up more pressure than normal. The wet plugs are the ones that bother me...whenever I pull my plugs they are bone dry like number 6..I pull the fuel pump relay when I do a compression test so Im not spraying raw fuel into the cyls...also jam t/b wide open or close to it
Last edited by bluejeep2001; 03-23-2021 at 05:59 PM.
Reason: more info
Watch some videos of how to Seafoam through a vacume line. Engine has to be up to temperature first. Do it somewheres where your neighbors won't see the black cloud that comes out of the tail pipe.
I've seen my share, but without combustion in that cylinder it's going to have a hard time activating properly.
Originally Posted by Saudade
LOL, when I seafoam mine, my XJ turns into an Ag Cat.
Last rig I ran seafoam through was an early 90s Explorer, it billowed smoke so badly I thought for sure the FD was going to show up at my house.
Originally Posted by bluejeep2001
I run a stroker and all my cyls run at 180..all fire off with the normal spark source...hook the plug wire up to a spare plug and ground the threaded section to the block or battery neg with an alligator clip..have someone crank or let it run if possible...you will know in a few seconds if your sparking on nbr 6..to get to 180 or any normalish number the intake has to open to let in air. If the exh does not open, that might allow you to build up more pressure than normal. The wet plugs are the ones that bother me...whenever I pull my plugs they are bone dry like number 6..I pull the fuel pump relay when I do a compression test so Im not spraying raw fuel into the cyls...also jam t/b wide open or close to it
This is interesting, thanks for sharing your experience with the higher PSI. I don't see how #6 couldn't be producing spark if the rest are being a cap and rotor but I'm down to try at this point.
From everyone's recommendations I'll try this again with the fuel pump relay shut off, and specifically test the #6 spark plug/wire for spark.
look down the spark plug hole with a borescope, cost cheap as $20, that will possibly show if you have stroker pistons inserted, maybe other stuff as well
look down the spark plug hole with a borescope, cost cheap as $20, that will possibly show if you have stroker pistons inserted, maybe other stuff as well
I've seen my share, but without combustion in that cylinder it's going to have a hard time activating properly.
Last rig I ran seafoam through was an early 90s Explorer, it billowed smoke so badly I thought for sure the FD was going to show up at my house.
This is interesting, thanks for sharing your experience with the higher PSI. I don't see how #6 couldn't be producing spark if the rest are being a cap and rotor but I'm down to try at this point.
From everyone's recommendations I'll try this again with the fuel pump relay shut off, and specifically test the #6 spark plug/wire for spark.
I should have said but didn't, after it's hitting on all 6, Seafoam.
Spark plugs: don't laugh but try a fresh set or borrow a set just for testing purposes.
a borescope that connects to your phone or laptop and fits down the hole is so cheap, I spill that much drinking on friday night
even if it tells you nothing, its easier and cheaper than pulling the valve cover, then cylinder head, which you will probably have to do, if the motor is running poorly
you can look up your pants with it when finished lol
03-23-2021, 10:22 AM
Runs like garbage - 180ish psi on Cyl #6
