99 Purple XJ

Once in a while ill be driving and ill take off from idle and it feels like it has no power up to 2K RPM then after like 3 seconds the power just comes back and it takes off normal it feels like it just loses power for those few seconds any ideas? It only happens once in a while

VTJeep

CEL? Sounds like a TPS, IAC valve, CPS or o2 sensors.

99 Purple XJ

No CEL had it scanned no codes IAC and everything was cleaned sometimes when i come to a stop the RPMs will go to like 200 and then come back up

BenReilly

Just wanted to see if you ever resolved this 99 Purple XJ.

I think I'm having the same issues. When I take off it's like it has no power for a few just a bit, sometimes I can give it more gas and it will go ahead and power out of it, but If i'm going slow it takes a bit to get it going. After the vehicle heats up and I've been driving for awhile, it seems to correct it self. Does the same thing the next time I start it up when it's not warmed up.

Also, I've got a 98 xj 4.0.
I've been working on trying to fix my issue and so far I've changed out my fuel pump, tps, and plugs. After I changed my plugs it didn't do it for about a week but has just since started back up, any ideas? Also, right now I'm without a cat, I pulled it off a while back thinking that it was clogged up (had a bronco do something like that before and that was the cluprit). The only code I'm throwing is P0420, I'm going to try and replace the O2 next and see if that will help it out any, but it was doing this before the code started showing up.

jowint

Ben, have you checked your connections at your PCM?

Flex them with the engine running to see if it acts up and if so, you found your problem.

BenReilly

Will do, thanks for the pm and help as well!

tetrad

I'm having the same issue. Replaced TPS + cleaned IAC, upstream+downstream HO2S ... each one seemed to temporarily resolve the problem, but it keeps popping up.

CEL was permanent for a long time, replacing these each made it go off for a good while, but now it's back.

At this point I've been eyeing either the crankshaft position sensor or the camshaft position sensor. I'm hoping it's not the PCM itself, but I will at least try flexing the connectors...

Maybe I should just go get my codes read :-D

BenReilly

I cleaned my IAC and throttle body really good last night, and I also wiggled the heck out of my pcm connections, no sputter there. Still randomly losing power. I guess next on the list is checking the O2 sensors, and then swap out my plug wires and the rotor cap. Going down the list of cheap things first.



On a side note, a few weeks back I did get a new crankshaft position sensor, apparently it was out of spec or something and was causing some strange grinding sound under hard take offs. It also didn't fix the power loss. I took that one back off and put the old on, I figured that it wasn't the culprit.

Joedirt12

Don't forget to check the map censer. I had a problem kinda like this and it wuz the map. 100 bucks at the auto store.

BenReilly

I'm a newb when it comes to electronic stuff, how can you check the MAP sensor without replacing it???


Also, I just had a flash, and it may be a dumb question, but could a bad batter cause engine stutters??? I know my batter is weak, I've had to charge it a few times due to this reason or that. Today, I went inside the house for maybe 2 minutes and left the lights on without the engine, and it was extremely weak to start.

BrofessorXJ

Lol just had this exact same problem the other day. Swapped out my upstream O2 sensor for a nice Bosch and the problem is non existent now. Improved fuel economy and power restored.

In your case I would test all the O2 sensors before throwing sensors at it to see if you can find one not working properly. The CEL will ONLY come on if your O2 sensor is stuck running a certain way like rich or clean or something I forget. I believe you have 4 O2 sensors on your 97 so I would start with the ones CLOSEST to the engine or before the cat. Also I read about not just the 02 sensor being shot but all the wiring back to the engine faulty as well check that.

I got lucky without testing. I figured it was the O2 sensor since I was getting 11mpg.

Part for my 96

BrofessorXJ

Better yet here was my thread on the issue

https://www.cherokeeforum.com/f2/im-...d-help-112762/

BenReilly

Brofessor, I just read your thread and that is EXACTLY what it's doing. I'm off to the auto parts store tomorrow to give this a shot. I'm not familliar with where all the O2 sensors are at, but i'll figure it out. Is there anyway to test and see if an O2 is bad? Or do I just start replacing and see whats going on?

BrofessorXJ

Well first off check the wiring on the sensor and back into the engine bay and make sure its not just faulty wiring. As for electrically it, I'm assuming you would need a volt meter and i'm not exactly sure what or how many volt's it should be at. Mine was never replaced so I knew I had to eventually why not now? The sensor is located just after the exhaust manifold. Your XJ might have 4 sensors being a 97 mine, a 96, only had two and i replaced the one before the cat on the exhaust down pipe. Maybe someone else can help with the exact locations of yours but i'm guesstimating as long as your replacing the one closest to the engine you should be good. When replacing it let your rig warm up a bit 20-30 minutes or so to get it hot so you can loosen it. All o2 sensors should be universal and I think its a 7/8" wrench. I personally bought a special socket at pep boys that has a slit down the side of it so I can torque it with a socket wrench and that got it right off. Then its just plug in and I zip tied down the connection. I'll post some pics here in a bit

BrofessorXJ