Jeep TJ 2.4 stuttering bad

EAGLIN

EAGLIN

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Joined
Feb 22, 2023
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22
Location
Fairfax, VA
So last week my exhaust grew a crack and started sputtering really bad. I decided to try and reset the pcm on the side of the highway and that made the issue magnitudes worse. So I drove it home and I fixed the crack and started it up again and there was still a leak. Then I realized the gasket was bad so I replaced that and now I head 0 leaks but the engine idles like crap and runs like crap. It intermittently sputters. And it’s giving me no check engine lights. I’m completely shooting in the dark here. I just replaced the spark plugs and o2 sensor with NTK ones 5k miles ago. It has a fresh coil pack. It’s like it wants to run so bad but it’s shooting it’s own foot.
 
The smart thing to do here is find someone with a live data diagnostic scanner and see what it's doing in real time. That's going to be the difference between fixing it the first time and wasting money by throwing parts at it.
 
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Chris said:
The smart thing to do here is find someone with a live data diagnostic scanner and see what it's doing in real time. That's going to be the difference between fixing it the first time and wasting money by throwing parts at it.
Click to expand...

I have a live data scanner, what should I be checking? And where should I go to see what the values should be. Or would it be easier to just take it to a shop and have them diagnose it for me. I like learning and doing things myself if possible.
 
EAGLIN said:
I have a live data scanner, what should I be checking? And where should I go to see what the values should be. Or would it be easier to just take it to a shop and have them diagnose it for me. I like learning and doing things myself if possible.
Click to expand...

I'd start with monitoring the O2 sensors as mentioned.

On YouTube you should be able to find a number of videos that show you how to monitor the O2 sensors and what you should be looking for.
 
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I think the 02 sensor is good. The issue is persistent even when the MAP sensor and O2 sensor are unplugged and the engine runs in open loop. Any thoughts?
 
macleanflood said:
I'd start with monitoring the O2 sensors.

-Mac
Click to expand...

Chris said:
I'd start with monitoring the O2 sensors as mentioned.

On YouTube you should be able to find a number of videos that show you how to monitor the O2 sensors and what you should be looking for.
Click to expand...

Ok quick update, I loaded up the timing advance on the monitor and saw that it’s sitting at anywhere from 19-30. Now from what I’ve seen it should be around 9 no? Thinking I may have to do a timing belt replacement. Really hoping I haven’t cooked the valves in the engine. That’s a job I simply can’t do in the parking lot of my apartment. Timing belt I should be able to do. Also may be the camshaft position sensor or crankshaft position sensor. But I’m getting zero codes. Thoughts?

Here is a video of the issue.
https://share.icloud.com/photos/0d4n0f9upqR7y3Fk5eimV_rQw
 
Don't have a 2.4 so no idea of the timing curve.

Look at the O2s. Voltage should vary but stay under .9v. If it's a bad O2 or an exhaust leak or plugged cat then the PCM might chase timing to compensate.

-Mac
 
EAGLIN said:
Ok quick update, I loaded up the timing advance on the monitor and saw that it’s sitting at anywhere from 19-30. Now from what I’ve seen it should be around 9 no? Thinking I may have to do a timing belt replacement. Really hoping I haven’t cooked the valves in the engine. That’s a job I simply can’t do in the parking lot of my apartment. Timing belt I should be able to do. Also may be the camshaft position sensor or crankshaft position sensor. But I’m getting zero codes. Thoughts?

Here is a video of the issue.
https://share.icloud.com/photos/0d4n0f9upqR7y3Fk5eimV_rQw
Click to expand...

The 2.4 timing job is likely more involved than you think it is. May also not be a parking lot job depending on mgmt. It involves removing pretty much all belt driven accessories (alternator, maybe AC compressor, PS pump (don't have to disconnect any lines, just get them out of the way) and pulling the front cover of the engine off (what the pulleys mount to) just to get to the belt and water pump. Far from impossible, but not as simple as other vehicles.

Not saying you jumped timing or you should dread the job, but I'd be wary of it before just jumping in. Luckily TJ's are non-transverse. Doing a belt in a PT or a Neon involves dropping the engine mount out of the way. On ours it's just the front cover. Once the pulleys are off and out of the way, there's 7 or 8 bolts or so that hold the front cover on.
 
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