Bogging Down on the street after initial Start-Up

Hey Guys,

I have been having this problem with my 97 when I first start up. The truck will start up fine and will idle pretty well (4.0L with 150,000 on it). Anyway after I put the truck into drive (has AW4) and start to drive down the road all of a sudden the truck feels to bog down right on the street like its loosing power and is about to stall out (this is with my foot on the pedal.) Once I feel it begin to happen I lay off the gas and the truck will stop bogging down and I can press on down again and it will drive fine after that. If I lay on the gas when it bogs down I will start to hear a clicking/pinging and a bit of shudder feedback (very minimal shudder from the truck itself and electronics stay lit without fluxing) coming from directly in front of me and I can feel the reverberations on the gas pedal as well. This also only happens under 30 mph. Which makes me wonder if its a transmission problem and not a engine problem because maybe its having a problem slipping into a higher gear? Like 1st to 2nd? It happens infrequently both cold and warm days and has progressively gotten worse over the span of a few months (happens on a more frequent level now). Ive let the engine sit and warm up for longer periods and it will still do the same thing. Also the engine has a minor leak from the head (rear passenger side of block) which makes me think its about ready for a new gasket and a possible valve job; not sure if that helps any. I keep the truck pretty well maintained and it runs well and this only happens when it has not been driven for an extended period time (10-12 hours +).


Any help or advice is greatly appreciated as I begin to troubleshoot this problem I am having- Thanks for taking the time out to read it

Test the TPS for any dead spots, check out your MAP sensor as well.

XJMuscle98 said:

Test the TPS for any dead spots, check out your MAP sensor as well.

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Agree.

Sounds *kinda* like it's getting leaned rich. Too much fuel, not enough air getting to the cylinder. If your cat is getting clogged at all, it could cause the symptoms you're describing. It just seems a little too intermittent though. Sensors are a good spot to start.

What kind of leak around the head?

this is exactly the symptoms I was having a few months ago. I would also bet on the TPS and/or MAP, I haven't replaced mine yet because it abruptly stopped doing it almost completely as soon as I bought a spare. I keep it in my glovebox as insurance / to scare my XJ into behaving because I have the parts to fix it on hand.

Hey guys I was away for a week, thank you for the info I'm gonna check these situations hopefully one sticks

Oh and BTW, the leak around the head is coming directly from underneath from the back of the engine bay, it but its not dripping just seaping out a very little bit you can see it stained the side of the block like how a drop of water spreads on a t-shirt but doesn't drip.

flazz85 said:

Oh and BTW, the leak around the head is coming directly from underneath from the back of the engine bay, it but its not dripping just seaping out a very little bit you can see it stained the side of the block like how a drop of water spreads on a t-shirt but doesn't drip.

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Post a picture of it.

Ill drop a pic soon, my old camera sh*t the bed so im gonna pick one up monday after class, hopefully then I'll drop a pic for ya. thx for checkin in

dont know if this will help your problem but i have a 97 and for longer than i care to say was hard to start had to feather the gas to take off ran real rich would die whenever and would even idle up on its own all the time. hooked up to diagnostic and showed map sensor to be the problem. ordered it 4 different times at local parts store ($100) and every time it came in i was either broke or didnt want to spend the cash or when i decided to buy it they had sent it back. long story short i found somewhere on here to unplug the coolant temp sensor and see if symptoms went away. and they did. CE light stayed on as did the electric cooling fan. bought new CTS ($16 in stock) and cleared computer and havent had any problems since. true story. i was there.

My mom's 97 ZJ did the same thing. I tried for years to fix it, and it never went away. It was really random when it would happen. Sometimes, it would happen every day for a week...then not happen again for a month.

My 01 did it a couple times since Ive owned it. Maybe 3 times. I attributed the first couple times to the heat soak issue on the injectors. Because it only does it AFTER its hot and sitting for a few seconds. I insulated a couple injectors and it seemed to help.

Good luck figuring it out. I replaced the TPS on my mom's jeep... TPS/MAP/IAC...I can see them all having a chance of causing the stumbling.

J.

makes sense that it could be a computer problem, i just need to pay this round of bills and can have reading taken and go from there. If money weren't an issue it be nice to get a OBDII flasher/reader.
I just tuned the truck up for winter and its idling pretty damn good now, but the bog is still there so im definitely leaning on the TPS/MAP. cool thx for the advice guys