pineapple_tree

I’m going to start off saying I have absolutely no idea why this happens, and I would really like to remedy it.

So, if my Jeep idles at a stop when it’s warm, it idles at about 1.1k. Not the best idle, and yes I’ll fix it, I just need the parts to come in.

Now, let’s say I rev the engine while idling. It will come back down, but hang up at about 1.3k, idle down to 1.1k, and be fine. But, let’s say i’m going down the road, go from 1st to 2nd, and when I push the clutch in, it stays at 2k, as if that’s what i’m idling at. This makes my shift very rough and unpleasant.

It will do this throughout any gear, and it doesn’t do it every time I shift. It does it for a while, won’t do it for a while, and then does it again.

To start, i’ve replaced the TPS with a Mopar one, thinking that the magnet was messing up and telling the PCM that the throttle was still open. Didn’t fix it, but fixed another stutter I had.

I also replaced the IAC with a good brand, I forgot what the name was. That IAC actually works, unlike the other one I had before it. I’ve also tested it, and it works as it should.

So, what’s next? Could it be the throttle plate hanging up, or the PCM starting to go bad? I would really like some input on this because i’m getting tired of looking like an idiot when this thing bucks back and fourth and having my girlfriend look at me with a stink eye because it’s annoying and tosses her around like a rag doll sometimes

pineapple_tree

Figured it out.

The bolts on my manifold, particularly the ones in the rear of the manifold at cylinders 3 and 4, had worked themselves loose. So, after it warmed up and it was steaming hot under there, I tightened down the bolts and torqued them down the proper way. I didn’t have any loctite, so I think this should work for now.

My guess is, the leak wasn’t big enough for the MAP sensor to detect it at idle, but if I was driving, there was a lot of excess air entering in, and the MAP sensor detected it, and told the PCM to “idle” accordingly. Since you go to neutral when you push the clutch in, the PCM went to idle mode before the clutch was released, and that’s what was causing my rough shifting.

I still have a leak at the bushing for the throttle spring and a slight leak at the end of the manifold, and that’s due to the mating surface of the manifold being warped, probably because 293k miles of heating and cooling took it’s toll on it.

Regardless, I have a guy making me a ported intake with the 4.0 TB, and the throttle body mounting point is being bored out to match the 4.0 TB. So, that’ll fix two vacuum leaks I have, and that should be the end of vacuum leaks for me. And who knows, with that intake and TB, combined with 4 hole injectors, long tube headers, some roller rockers. IAT relocation, and an electric fan conversion, I think I could actually start seeing some decent gains. I have a whole write up on what can be done to make the 2.5 less unbearably slow, and I’ll try and dyno it before I do any “mods”, and then dyno it again with all the mods combined. I’ll also try and do a pull with the A/C on before and after and see if there’s any difference, because if anyone has the 2.5, they know that the A/C makes this thing slower than you thought possible.

But at least it moves. And gets good gas mileage. It’s better than some cars i’ve driven

DustyWagoneer

Real dyno numbers or nothing at all.

As someone who has a stroker 4cyl. I wanna see REAL numbers or the ban hammer comes out!
No more BS on this site!

lawsoncl

I had a YJ 2.5l manual for a while. It felt very under powered even for the claimed 130-hp, and struggled to hold 40 going up the passes in 3rd gear. Now my 2014 KL with 271 HP flies despite the 4000 lb curb weight.

pineapple_tree

Well, slight hiccup. Anyone who has a dyno, only uses it for tuning. no one can take me in for just a dyno pull without tuning. And anyone who can take me in can’t do so until the middle of the year.

So, I have to improvise.

There’s a flat strip of land near my house that’s more than long enough for this this to reach nearly 80 (which is painfully long and scary by the way), so my thoughts are this:

3 runs from the same point, run it out to redline, and continue until I reach 60 on my speedometer. Granted, the actual times are faster because my speedometer is off by about 5 around 60, but it will suffice.

I’ll do 3 runs down the same strip with around the same conditions, because as it turns out surprisingly, a box going down the road is affected by winds. I’ll try my best to keep all the variables the same, and average my time on the 3 runs after each mod.

Granted, it’s not on a dyno. I really want to get this dynoed and graphed, but unless I find someone by the end of next week that can take me in, I won’t be able to establish a baseline before I do the first two modifications, intake and exhaust.

lawsoncl

Don't forget to adjust your numbers per SAE J1349. :}
https://robrobinette.com/Dyno_Correction_Calculator.htm

Personally, I'm guessing you won't see more than a 1-second improvement on the 0-60 time.