pr0metheus

So I just bought an '03 WJ 4.0 last weekend.

After 200 miles with it this week I have two problems that I need to address and I think it's possible that they're linked.

First, it's taking a long time to start. It helps it along if I step on the gas pedal. So that has me thinking fuel pressure, fuel pump, something along those lines.

Also, and more concerning to me, the jeep will buck or jerk if I'm driving and step on the gas for a second, and then let off. Example, if I'm at 1500 rpm then briefly go to 2500 rpm, once I let off and the rpms come back down, there's a very uncomfortable feeling and noise coming from underneath the jeep.

After browsing the forum I've found that this bucking behavior can be a fuel issue, so that's why I think that these two problems may be linked.

The jerking that I'm experiencing really feels like a transmission/shifting issue but I really have no idea.

Any thoughts or input would really be appreciated. Thanks

Cherryokee

There's too much bucking and jerking going on here. How does your tranny fluid look, smell and feel (between your fingers)? You might want to check and/or adjust your kick-down linkage too.

pr0metheus

Agree.

Tranny fluid passed the look/smell/feel test but I'm going to change it and the filter anyway.

I will play with the kickdown cable tomorrow. Thank you for that suggestion. I hadn't even considered that but just found an entire thread about it...complete with another poster who had similar symptoms.

dave1123

It's entirely possible the PO installed bigger injectors and your mixture is very rich. The PCM should compensate, but not if they are the wrong ones for the engine. It sounds to me like the extra fuel is burning in the converter and causing your noise underneath. I've seen converters blow up because of fuel igniting in them. Try a junkyard set from another 4.0 and see if that solves the problem. JMHO.

pr0metheus

I changed the spark plugs and it did not help with start up issues. Although they were in awful condition.

I adjusted the kickdown cable and I like where it's shifting now, but it has not fixed the bucking on lower gear down shifts.

pr0metheus

Would I be able to learn anything about the injectors from the data stream on a code reader?

I have a reader and have looked at the data stream, but I don't really know what to look for.

Thanks

papablista

I don't know about a 93 but for a 2000 it is easier to go from underneath! Not a big deal easy job altogether.