'97 4.0 5 sdp,

I've had this symptom ever since getting the xj about a year ago. No codes, fuel pressure is good and constant, also does not loose pressure after shutoff. When I start her in the mornings and proceed down the road I experience a huge momentary bog when I shift into second and give it gas. I don't think it has anything to do with shift, it's just when it chooses to happen most times. After it recovers after a second, its fine for the rest of the day. Just wondering if anyone might have an idea of whats going on. Thanks!

 

Mine used to do the same thing. But I had a bad fuel pump. It took 3 tries to get it started and drop psi instantly whwn turned off. After a new pump and an upgrade to the 4 hole injectors, its much better. I also did a new o2 sensor at the same time. Mine also only did it when not up to temp. So im thinking it also had something to do with the o2 not being in closed loop.

 

sounds like it might be a common issue with these.... Mine does it every so often...but like 5-speed mentioned..... I've noticed that mine will only do it if not up to temp yet. If I have to take off before I'm up to temp, if I just take it easy for the first time through the gears, I can help to keep it from happening. Then once up to temp, I don't seem to have the issue anymore. So I just chalked mine up to that.... at least for now. lol... after all.. they are Jeeps.

 

Mine has done this before and rarely does anymore. Before i had my cel light on for a faulty evap purge valve it did it almost everytime my jeep sat for more than 5 mins but after a few months of neglecting and ignoring the cel it mysteriously turned off and my mpg came back and like i said rarely happens it only did it once after the light turned off so idk if it was throwing my sensors off making it run very rich or lean. Also i reset my computer on my jeep and has been dandy ever since.

 

be careful....lol.... "dandy ever since" and "rarely happens anymore".... statements like that will send a personal invitation to Murphy priority #1. lol. And I like to avoid that SOB as much as humanly possible.

Mine doesn't do it all the time either... only thing I've noticed is if I go to take off and I haven't let her warm up at all. But if I let off on the pedal just a bit, it comes back and once warm, issue seems to go away. So I just chalked mine up to that....for now anyways. lol

 

knocked on my wooden desk hopefully it worked lol

 

but yeah usually mine i just stab the gas pedal and itll clear itself out

 

If anyone needs the info, just a followup. this ended up being a bad ECU!