Bucking, Loss of Power, and shutting down.

[Flatbed Junk]

So I finally went out of my way to make a profile on these forums because I've had enough of my Jeep, and I would love to drive it. I got this 87 Commanche about a year ago, and I haven't really been able to drive it because every time I drive it, it loses power and shuts down. Or I give it gas and get no acceleration. 

Over the past months, I've done a fuel pump and tested some sensors like the TPS, MAP, and CPS, with still no change in its behavior; the only thing that changed is no more loud fuel pump (yay). 

Other symptoms. I get good acceleration for maybe 5 minutes, maybe an hour, after startup, and then it falls flat on its face, dies, and has no power whatsoever. I'm new to Renix jeeps and have no idea what to do from here! Any advice on what to do would be much appreciated! Should I just start with sensors and vacuum lines? 

[eaglescout526]

Welcome! 
 

Which engine is it? But I think I’ve seen your posts in FB about it being a 2.5L. 
 

If it is the first thing that comes to my mind is condition of the fluids and notably the cooling system. My MJ when it had a bad headgasket would do very similar things to what is happening with yours. 

[Flatbed Junk]

Yeah, that's me, and it's a 2.5. My coolant looks kinda gross, but I tested it, and no gases are making their way into my cooling system. 

[eaglescout526]

24 minutes ago, Flatbed Junk said:

Yeah, that's me, and it's a 2.5. My coolant looks kinda gross, but I tested it, and no gases are making their way into my cooling system. 

Brown probably?

 

Mine didn’t leak exhaust gases into the cooling system but it sure would overheat and or make the overflow just boil over. 
 

Both on my eagle and MJ the gasket was failing just enough to let water into the combustion chamber and cause it to not ignite. 

[Flatbed Junk]

I haven't had any overheating issues really at all. The main problem is it's fine at idle with a little surge sometimes, but when I take off it's fine for a little while, and then I put my foot on the gas, and it's just nothing! It stalls completely or just bucks around violently until I ease up on the pedal and limp home.

It seems to happen so randomly that it's just irritating, but I don't even know where to start. It's almost like a sensor is telling it to stop putting fuel in. 

[fiatslug87]

Check the EGR system.

[eaglescout526]

Oh yeah EGR is a good one to check too. 

[pizzaman09]

I know you have a 2.5L and my experience is with the 4.0L engines but I suspect this applies.  I've had issues that cause this sort of bucking caused by exhaust leaks from the exhaust manifold before the O2 sensor.  Check to see that the intake/exhaust manifold bolts at the head are tight and all present.  If not it can be leaking and you might even have a bad gasket there.  You could also have a crack in the exhaust or even a bad O2 sensor.  

 

The symptoms change as the exhaust system heats and cools along with thermal expansion.

[llhat]

checked for a clogged catalytic converter...