jeepxj99

I was driving my 99 jeep xj home tonight and all of a sudden my rpm drops to zero and my vehicle starts to slow down until the motor cuts off and I no longer have any power steering. The lights never go off or dim. I get it to the side of the road and turn my flashers on. I cut my key to off position and try to restart and it just tries to turn over but won't. So i cut key back off, sat there about a minute and tried again...fires right up...runs for almost 20 seconds and cuts off again. at this point my check engine light comes on for all of 5 seconds before going off again. I call someone to come help and when they get there, it cranks right up and I am able to drive it home. what in the world? please give me some ideas.

***backgrounds info***
for several months at random times the vehicle would buck while at normal speeds (55 to 60 mph) and once or twice the rpms dropped out instantly before and the vehicle would slow down but before it never cut off. they would drop to zero and i would slow down until it kicked back in all of a sudden. took it to a mechanic who drove it for 2 days and it never did anything with him. no check engine light tripped before

VTJeep

Sounds like I could be a number of things- TPS, IAC, o2's, TCM... All because the CEL isn't on doesn't mean there isn't a code or tow, or three... stored in there than can point you in the right direction.

Also.. The possibility that fuel delivery was temporarily obstructed would def. provide for that weird buck when driving. If your up for it, get really low on gas and drop the tank to inspect it. If you have the inline filter, start by checking the filter for swag.

jeepxj99

Yeah I am going to take it in the morning to have the computer checked for codes. I feel you on the fuel deliver. I thought for sure that after the motor off and then wouldn't start that my fuel pump was on the fritz. But then it starts up and drives home? Never had a fuel pump go out and then it work intermittently. Everyone keeps saying its electrical but I have no idea. I guess it could be electrical from the fuel pump?

VTJeep

Haha, it never got bad enough to shut the motor off, but there was a considerable amount of dirt and leaves in my 99's tank that caused this issue. Idk.. Still, your doin it right by going and getting it on a reader... I still wanna say o2 sensor/s.

stev-o

If u have a cps I would look into that

VTJeep

He does, and it's a potential.. Good call.

jeepxj99

cps sounds like a good idea, but can someone explain why it would cause those symptoms (cutting off, etc...)? same for 02 sensors? thanks

1991Jeep_Man

IIRC, when the CPS fails, the computer basically loses track of where the crank is and what is going on at each piston. I may be wrong though, but usually when a CPS is failing, it results in random crank-but-no-start's and craziness of the sorts.

Another suggestion... did you upset the XJ? I have come to realize that XJ's are very sensitive, and if hurt they will do random crap. Lol

stev-o

The cps runs close to your exhaust and is mounted to your bell housing so it sees alot of heat and wen they get hot enough it could fail and then wen it cools off could allow u to start your car again until it heats up and starts cuting out again
Cps always go bad on these xjs.

jeepxj99

makes sense

jeepxj99

a guy just told me to have my alternator checked because his truck did the same thing about a year ago and it turned out to be the voltage regulator in his alternator....this sound like a lead at all..cuz i have no idea

stev-o

Have the battery tested at the same time then

1991Jeep_Man

Negative. His XJ musta been a RENIX, which is 89 and prior. Yours is a '99, so the regulator is built into the ECU itself. Renix have a regulator built into the alternator.

jeepxj99

well i thank you for the information...i'll keep it updated as i find out what is wrong...hopefully the code that got tripped tonight will be in the stored codes.

jeepxj99

Well folks....this morning I woke up and drove my XJ to the closest mechanic (about a half mile) and had him check for codes. Believe it or not, no codes were set for the light last night. I couldn't believe it. So guy tells me he doesn't know what to tell me. Suggests ignition coil (same excuse he gives everyone no matter what vehicle or so i hear). Anyhow I drive back home and a little later go to take it to another mechanic and I crank it and it cuts off in like 10 seconds. Then won't crank again. Just lags...urrr urrr urr. Then it cranks next try. So I am driving to the shop and it stutters (tach drops and throws light on for moment tach is at zero) and continues on. So i get almost there and it just shuts off at the stop light. Wouldn't crank just urr urr urr again. Then we push it out of the road but it cranks again...and me not knowing for how long I had to have it towed.

Just don't want to the dealership to give me crap...it can't be in the battery or cables cuz my lights stay on the motor just dies. If it were the crank sensor I think I may get a code stored. I would think the computer would cause more problems than just that.

Never thought of this before but maybe its the cam sensor (in distributor in that model)

Any thoughts???