[iflyabeech]

I just upgraded to a 1999 Cherokee 4.0 4x4 5 speed . . . I was accellerating on the highway, going through 55 MPH in 4th gear and the Jeep kinda hesitated, and the check engine light came on. It seemed to have lost some power. . . Would not go over 70MPH. . .I stopped, then accellerated again and accelleration felt normal. . . and Jeep had no problem getting over 70. . .I am going to try to get the trouble codes fromt he Jeep. Any one have any clues as to what my problem might be?

Thanks!

[JeepCrazyKid]

way easier to get your codes first and see where to go from there. Could be lots of things.

[iflyabeech]

OK, I we had already unhooked the battery and reset the computer before I got the codes. . .I drove around today and tried to get the problem to repeat itself today bith no luck. . .I have to take it on a road trip this week and would like to figure out the problem beforehand. . . Any ideas?

Thanks

[iflyabeech]

Ok, I went out and drove the Jeep again. I did not get a light this time but it does not accellerate properly and it just seems to have a lack of power. It seems to be worse after it has warmed up. It seems to accellerate fine in the bottom part of a gear, but after revving to a higher RPM, it seems to be limited. It almost feels like you have more power when you upshift. . .I am thinking it could be fuel injectors, fuel pump, Cat. converter, or fuel filter. . . Could it be ignition related? Please help! Thanks!

[iflyabeech]

Come on guys, I have been checking this often today and noone has replied. . .Someone has to have had this happen to them before. . . Please help!

[Alexia]

Fuel pump, oxygen sensors. You should hear the fuel pump buzz when your put the key to On/Run. Check your spark plugs. Basically go over all the usual maintenence items.

[nwfxjguy]

Similar thing happened to me several years back. I have 94 XJ, and it would hesitate and cut out, but always start. Had it in the dealer several times, but no resolution. They finally hooked up the computer to try and capture any codes, but it wouldn't fail. I took a look at the rotor and cap and noticed it was corroded. I changed them and all was fine. At the time it was less than a year old, so I guess no one thought it could be the cap and rotor.... The difference is your getting the check engine light. I don't know if that would cause the check engine light to come on in the newer models, but that is what I've got to offer...

[Alexia]

Originally Posted by nwfxjguy

Similar thing happened to me several years back. I have 94 XJ, and it would hesitate and cut out, but always start. Had it in the dealer several times, but no resolution. They finally hooked up the computer to try and capture any codes, but it wouldn't fail. I took a look at the rotor and cap and noticed it was corroded. I changed them and all was fine. At the time it was less than a year old, so I guess no one thought it could be the cap and rotor.... The difference is your getting the check engine light. I don't know if that would cause the check engine light to come on in the newer models, but that is what I've got to offer...

90% of the time the check engine light is oxygen sensor goind bad. That doesn't usually cause this problem though.

[lbsnowryder]

I had this happen and even paid to have it ran on a diagnostic. Unfortunatly it wouldn't do it in Nuetral. It ended up being a line on the fuel pump. It's hard to say cause your's is a 99. That is only a guess and hope it puts you in the right direction.

[iflyabeech]

Thanks for the responses. . . . I will have it checked out today. . . Now it is not giving me a check engine light!

[badron]

OK, I say start over with the basics. You need a can of contact cleaner. Go over every plug under the hood. check every vacuum line under the hood. Check or change filters etc. Check to see all grounds are clean and snug.
A 99 how many miles on the plugs. They could be getting weak but still test good on them F***edup computers. Even if new pull them. Check the plugs for anything unusual. Plugs are you eyes inside the engine. Lean to read them. They can tell you so much. Check plug wires cap coil etc. Do a night time under the hood peak. Watch for sparks.
Got a vacuum gauge? Hook her up. At idle it should read about 25 or so. It should be steady as a rock. The key here is steady. Any change of 2 LB or more may mean problems.
Got a fuel presser gauge. Check that out. When I say gauge I mean a REAL gauge not the computer readout.
I ***** about computers a LOT. It not the computer fault. Most shop just want to hook you up to one and if that don't find a problem they want to give up. They just don't want to spend the time digging in and finding what's wrong. They want you to drive it till it completely goes out. Then they can find it.
The best testing gear you got is between your ears. Use it.

R Robinson

[JeepCrazyKid]

Originally Posted by iflyabeech

Thanks for the responses. . . . I will have it checked out today. . . Now it is not giving me a check engine light!

Still check for codes anyway. You don't need a check engine light for it to throw a code.

[badron]

Sorry double post can't delete

R Robinson

[BeachinXJ]

YOU need to get the codes pulled!

[iflyabeech]

I tried getting the codes via the "hold the odometer button down and reset the key switch 3 times and all it did was count and flicker the gauges. . .no codes!

It drives wonderfully when it is cold, but after it warms up it just won't go! All I could get in 4th gear was 72 MPH and 75 MPH in 5th. . . .Yes, it is a 4.0!

I am thinking it could be the cat. . .but I don't hear much hissing!