phantomboda
NAXJA Forum User
So a little over 4 years ago I was a senior in high school with a horrible case of piston slap on my first car - my 2000 XJ 4.0. I decided it would be a great learning experience, and cost about as much as buying a new old car to replace the engine. I took it apart, got a crate remanufactured engine from Autozone. It was awesome! I learned so much about my Jeep and cars in general. I probably didn't do everything right (foreshadowing) and should've replaced parts that I didn't, but i did it. After trying to start it up, realizing I didn't index the cam position sensor oil pump drive right, fixing that, and then hearing her roar to life I was ecstatic! My jeep was alive! Per the engine manufacturer's instructions, and what I heard online I broke it in, staying under 40 (or 50, it was 4 years ago I can't remember) for 500 miles, I changed the oil when I finished and took it for its maiden highway voyage. It didn't go well. I'll describe later. Over the last 4 years I've been intermittently trying to fix this issue since I've been away at college and the jeep wasn't able to join me because of the highway issue and other factors. Well I'm back, and with a summer to fix it.
So, the issue is thus: My jeep starts fine, idles fine, maybe a little loud, maybe a little shaky. I don't remember how it was before the replacement. Like I said runs in the city fine, maybe less power than it's supposed to have but again, nothing to compare it to and memory doesn't serve. Once I get on the highway it drives alright for a while, gets up to speed. The only possible issue is maybe a pulsing vibration, more like a sound, like the engine/tire noise is going up and down slightly in pitch. After a few minutes, less if it's hot outside/the engine is already hot, more if it's cooler, a ticking/clacking noise will start. It sounds like it's coming from right in front of the gauge cluster, maybe from the driver footwell. That is the harbinger that bad stuff is about to begin. After the ticking starts, pushing the throttle doesn't provide any noticeable oomph. It can mostly maintain speed but won't really gain, rpm's stay mostly constant. The jeep then begins to buck, more like it's losing power and gaining it back quickly than it's surging and stopping-but may be. The shuddering continues at speed, gets more jerky as I slow down to exit and disappears under 40mph. A ticking sound has started though, different from the ticking/clacking that signals the shudders. It continues until while driving, especially if it stays hot, but it fades at idle and eventually disappears in the purr of the engine.
On a couple occasions when I have been pushing it to better understand the issue, I get a flashing CEL (and I stop pushing). I have also gotten a CEL for cyl 1 misfire (P0301) occasionally if the bucking is particularly bad.
I've run some tests to try to narrow the problem:
Compression test and all cylinders were around 150 psi
Fuel pressure test around 40 with ignition on, 51 idling and revving
Shifting into neutral to see if it's a trans problem - At speed when it starts bucking I've shifted into neutral and revved a bit. The ticking/clacking remains, obviously no more bucking because the engine is disconnected, but engine sounds bad enough that I think trans isn't the issue. I did get a trans code after doing this, which I felt might've been because I shifted into drive too soon after revving but unsure, only time the code came up (P0700).
Also, I have tried unplugging the upstream oxygen sensor, to see if that was the issue or an exhaust manifold leak lean condition was causing flooding and the misfire. This didn't fix the problem. It happened almost the exact same, except with an o2 code.
Here's a list of all the fixes I've attempted so far in order as far as I remember.
A few thousand miles before swap: new cam position sensor, and crank position sensor, new fuel pump assembly
During swap: New spark plugs (Autolite platinum)
Heat soak shielding on intake/injectors/fuel rail
Shop replaced coil pack (doesn't have manufacturer on it so not sure if it's a quality part)
Different shop flushed fuel lines and put new rubber hose on end of line that goes into fuel rail.
Moved IAT sensor to air box
Replaced:
PCM
All 6 injectors
Upstream o2 sensor
Throttle position sensor
Downstream o2 sensor
Catalytic Converter
Readjusted TV cable
Removed rubber splash panel I put in under engine after the swap to lower temp under hood (it gets pretty hot)
And that's about it so far. The issue hasn't changed with any of the "fixes"
Next I'm going to try to clean all the grounds and the IAC sensor, but if anyone can help figure out the issue I would be forever in your debt. I want to trust my jeep again.
So, the issue is thus: My jeep starts fine, idles fine, maybe a little loud, maybe a little shaky. I don't remember how it was before the replacement. Like I said runs in the city fine, maybe less power than it's supposed to have but again, nothing to compare it to and memory doesn't serve. Once I get on the highway it drives alright for a while, gets up to speed. The only possible issue is maybe a pulsing vibration, more like a sound, like the engine/tire noise is going up and down slightly in pitch. After a few minutes, less if it's hot outside/the engine is already hot, more if it's cooler, a ticking/clacking noise will start. It sounds like it's coming from right in front of the gauge cluster, maybe from the driver footwell. That is the harbinger that bad stuff is about to begin. After the ticking starts, pushing the throttle doesn't provide any noticeable oomph. It can mostly maintain speed but won't really gain, rpm's stay mostly constant. The jeep then begins to buck, more like it's losing power and gaining it back quickly than it's surging and stopping-but may be. The shuddering continues at speed, gets more jerky as I slow down to exit and disappears under 40mph. A ticking sound has started though, different from the ticking/clacking that signals the shudders. It continues until while driving, especially if it stays hot, but it fades at idle and eventually disappears in the purr of the engine.
On a couple occasions when I have been pushing it to better understand the issue, I get a flashing CEL (and I stop pushing). I have also gotten a CEL for cyl 1 misfire (P0301) occasionally if the bucking is particularly bad.
I've run some tests to try to narrow the problem:
Compression test and all cylinders were around 150 psi
Fuel pressure test around 40 with ignition on, 51 idling and revving
Shifting into neutral to see if it's a trans problem - At speed when it starts bucking I've shifted into neutral and revved a bit. The ticking/clacking remains, obviously no more bucking because the engine is disconnected, but engine sounds bad enough that I think trans isn't the issue. I did get a trans code after doing this, which I felt might've been because I shifted into drive too soon after revving but unsure, only time the code came up (P0700).
Also, I have tried unplugging the upstream oxygen sensor, to see if that was the issue or an exhaust manifold leak lean condition was causing flooding and the misfire. This didn't fix the problem. It happened almost the exact same, except with an o2 code.
Here's a list of all the fixes I've attempted so far in order as far as I remember.
A few thousand miles before swap: new cam position sensor, and crank position sensor, new fuel pump assembly
During swap: New spark plugs (Autolite platinum)
Heat soak shielding on intake/injectors/fuel rail
Shop replaced coil pack (doesn't have manufacturer on it so not sure if it's a quality part)
Different shop flushed fuel lines and put new rubber hose on end of line that goes into fuel rail.
Moved IAT sensor to air box
Replaced:
PCM
All 6 injectors
Upstream o2 sensor
Throttle position sensor
Downstream o2 sensor
Catalytic Converter
Readjusted TV cable
Removed rubber splash panel I put in under engine after the swap to lower temp under hood (it gets pretty hot)
And that's about it so far. The issue hasn't changed with any of the "fixes"
Next I'm going to try to clean all the grounds and the IAC sensor, but if anyone can help figure out the issue I would be forever in your debt. I want to trust my jeep again.
