So I have a problem, when I step on the gas under load or just when I rev it it bounces at 4300-4500 rpm like it's hitting a rev limiter. I'm not really sure what the issue is and 2 hours of research turned up jack sh*t.

The truck is a 2000 5.9 with 190k on it, I bought it in Feb with 160k and have been piling on the miles (thanks to running chauffeur for my mother-in-law) I haven't been able to put a lot into maintenance but then again the truck was only 2k, I've definitely gotten my money's worth out of it.

Now that I have had some money to put into maintenance I put new plugs, wires, cap, rotor, PCV valve into it and it seems to be running a lot better, idles smoother, seems to accelerate a lot better merging onto I-25, and is no longer pinging under load. I'm thinking maybe it could be a clogged cat? My last experience with a clogged cat was my first '94 YJ and it bogged down not bounced. I know these 5.9's have plenum problems, and I need to pull the throttle body to look in the manifold to see. I put from 500-1k miles a week on this truck so keeping it running with no catastrophic failures is critical.

 

176 views and nothing?

 

Really, 5.5 hrs later and you expect a crisp answer? Maybe it's that many reads because people are wondering what you mean by your odd title (I know I did). It's a really odd problem on an poorly maintained high mileage vehicle, easy to see why no one has seen it before. You might start by fixing the other things you mentioned that could use addressing.

 

Is it just the tach that is bouncing or the engine revving bouncing? Try to see if you can take it to autozone and run an OBD scan to see if there are any codes.

 

Well, when I typed it up at 3AM I couldn't think of what to title it, I'm more looking for idea's on what it could be besides what I suggested.

:Off topic: I've been reading your posts on JF for about 6 years, your YJ is killer, do you still have it?

The engine and tach are both going up and down I would say from 4300-4500 rpm down to 3700-4000 and back up.

 

Thanks for the praise. Yes, still have the Jeep, since 1996 with no plans to ever sell it or get another Jeep.

On your D problem, it could be a fuel injector issue (intuition/guessing). Are their any OBDII codes?

 

I checked for codes and it's throwing nothing, the only thing an think of is I got a replacement computer right after I bought the truck, maybe they messed up on the tuning somehow?

 

This is odd. The factory rev limiter in neutral is 5500rpm, WOT shift point is 4700-4800rpm . Hope this helps your diagnosis. It may be time to look at the cam senor or crank sensor, I don't think they will start if they are totally shot. Hows the fuel pressure?