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Discussion Starter #1 (Edited)
Got this jeep a while back (6 months). Had a cracked exhaust manifold when I got it so I replaced that and since then it has been running horribly. 98 wrangler sport 4.0L

When I start the Jeep, it idles at around 1300-1500 RPM's. The moment I hardly touch the throttle, the RPM's drop down to 400 for a moment and then would level back off around 800-1000. After all this was going on, I replaced the TPS and the IAC, and done a full tune up. The problem was still there. Also, anytime I am diving and I am in any gear (the clutch is dropped) the engine will randomly jerk like it cant decide if it wants to stop or go. This jerk gets passed down to my transmission and will cause the whole vehicle to drive around like a slinky. Moving in one direction of bouncing forward and backward on the way. It is infuriating to say at the least as I know my transmission is being destroyed when it happens. Obviously when it does happen I mash the clutch to disconnect the power transfer and save my transmission but it gets to my nerves.

The other day my car started running really rough and a check engine light came on. Now anytime I am not pressing on the gas, I'm sitting at about 200 RPM's and begging not to stall. I haven't gotten the code read yet cause I'm concerned about driving it to a shop and I'm a college student so I cant afford a code reader of my own. I have removed and cleaned the throttle body as well and am still having the issue. Tomorrow morning (1-12-2021) I am going to test the MAP sensor.

The only things that I can think of that would cause an issue like this is the MAP sensor and maybe the Fuel Pressure Regulator for the injector rail. If anyone knows of anything else that I can check with a multimeter and my tool kit, please let me know.

I bought this jeep so that I could fit it for overlanding and camping. I haven't even been able to get it running right in 6 months (Also had a steering knuckle break on my which I replaced). Any help will go along way. Thank you
 

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Los Angeles
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I would start by buying a Mopar TPS because your symptoms are that of a bad TPS.
 

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Los Angeles
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I chased issues that resembled a bad tps for 3 months because I had recently replaced the tps and "knew for sure that it couldn't be that".
After 3 months of off and on issues, my cel came on for the tps. I bought a better one, not a great one, and my engine is running great again.

maybe swap those out as defective, if you bought them with lifetime warranties.
 

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Discussion Starter #7
I chased issues that resembled a bad tps for 3 months because I had recently replaced the tps and "knew for sure that it couldn't be that".
After 3 months of off and on issues, my cel came on for the tps. I bought a better one, not a great one, and my engine is running great again.

maybe swap those out as defective, if you bought them with lifetime warranties.
Okay, I'm going to probe it with my multimeter in the morning and see what I get
 

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Discussion Starter #8
UPDATE:

I drove to the auto shop and got the codes run. Codes came back as TPS and crankshaft sensor. I replaced the TPS after probing it and getting back a 4V idle (should have been 5) and the problem seems to have stopped. I'm still very skeptical but that seems to have done it for now. I checked the codes again and got nothing back. I am going to let the engine cool and see how it runs from a cold start. I will keep you posted!
 

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Discussion Starter #10
That seems to have done it. Now the only thing that I have going on is a slight crunch going into second gear. When I go from first to second quickly, I get a slight grind and resistance. If I drop the clutch and pull out of first, wait a second, and then shift into second, the crunch is not there. I have been shifting slow to avoid it but if you have an clue as to what it might be I would appreciate it.

Thank you,
Christian Conkle
 

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That seems to have done it.....

Thank you,
Christian Conkle
Hey Christian, that's good news. Chasing electrical gremlins can be a pain. So where did you buy the TPS? Sharing the brand would help me, personally.
Thanks!
Ed
 
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