knup

Hi guys - I just picked up a 96 xj 4.0l and it's got a couple issues I could really use some help with.

While driving like normal at about 60mph every so often it will just completely lose power - it will start to slow down and the rpm's will rise. Giving it more gas just makes the rpm's rise higher but it won't speed up. If i pull over and turn it off for a couple minutes then fire it back up it is fine for a little while then trouble repeats. It doesn't feel like the trans is slipping though so I was thinking maybe the catalytic converter is clogged or an o2 sensor issue maybe but don't want to just start replacing parts. Hoping maybe someone else has had a similar issue before. Also some days it won't do this at all......

Other problem which kind of goes along with the first is when initially starting off from a stop in drive it seems like I really have to step on the gas to get it going then it feels fine. If I shift down to 1-2 to start off it feels more normal.

Any suggestions or feedback will be greatly appreciated.

ZINGGG

Do a tune up to begin with. Fresh champion copper spark plugs gapped to .035, quality spark plug wires, distributor cap with copper contacts and ignition rotor. When I got my 96, it would cut out like that at high speeds and I'd lose all throttle. Replaced the spark plug wires and problem fixed!

KD4315

Is your CEL on? Even if it's not on I would still hook up a scanner to it to see if there's any codes in there. The PO could have pulled the bulb.

knup

Thanks guys - I read the codes and it had three.

12 - battery disconnected in past 50 key cycles
21 - oxygen sensor or wiring faulty.
55 - end of codes.

So next question is could the o2 sensor cause this type of issue and if so any recommendations on which brand would be a good replacement. Also would guess it would most likely be the front sensor but any input on that would also be great.

ZINGGG

Yep, the front (or upstream as it is called) sensor is the one you want to replace. Order the NTK oxygen sensor from rockauto.com. They are the cheapest around and they are what came from the factory so you know they are quality