Why me

Im sorry to say my has not been doing good the last 2 days. When you slow down for a turn the engine starts missing and as your still rolling through town, not fun. :scared: Then when ture the key to start it evrything shuts off in the cab to. To get it to refire i have to disconnect the battery, hook it back up and starts with a 3 grand + rpm rev.

It doesnt do it all the time but always feel skechy.

Thank you.

Bad ground from battery to chassis?
Have you checked anything?

year would help..

1993, 347,000 miles. ran awsome till now.

Battery connections, grounds, battery voltage.

Changed the computer and it runs great agian. What would cause the computer to go out?

Thanks

a bath?

Dipstick.... Hehe

I like you little cherokee there.

tomhil said:

Changed the computer and it runs great agian. What would cause the computer to go out?

Click to expand...

The only real way to determine root cause is to perform failure analysis and that is rarely done on automotive components because it's cost prohibitive. If you're running well with the new computer, you should be good to go.

I'd double check your grounds and freshen them as a matter of course.

The main reason i call this thread, Why Me is because this is a frequent problem. This is my 3rd computer in a year.

The first time it was running bad it would shut off on the freeway and turn back on real fast and hit the rest of the jeep with a vengence. Went and had a diognastic test done. ( bad spelling in this thread) Change all the sensors i could, MAP, O2, air temp, both water temp, crank, and cam sensors. Nothing helped. And all this stuff is expensive!

So I when and got a computer, put it in and it worked. that was mabey 8 mounths or so.

Then is started doing what i started this thread with. It alsowas running slugish, took a while to start, and the engine was missing. So i didnt want to mess around agian and put another one in. OMG ive never felt such a difference in my jeep before. It starts so fast, the power, the trans shifts better, everything is cool agian except the cruse controle doesnt work now and that was and is very important to me.

When you turn it on you ca feel it grab the pedel for a spit seconde then it quits. I need some help there.

The grounds are good clean and new. the where done many times when i put a sound system in.

Cruise control problems are many times traced to a vacuum leak. Start with a very close leak of all the vacuum connections related to the cruise.

If you hold the cruse botten in it holds a speed, when you let go it lets go?

It did it agian! The grounds are fine. It idled to fast then to slow. Then it would just quit. Then it wouldnt idle, I had to keep it reved. Then it went fine agian. I changed it not to long ago but could the idle speed motor be at falt?

sounds like it could be. have you checked your tps?

Have you ever seen a check engine light? If so, you must pull the codes and see if that can help lead you to the problem.

The problem is definitely not the computer itself (not with 3 replacements) so I would check out the throttle position sensor as scully mentioned and idle air control circuits (including wiring/connectors) pretty closely.

Use electrical contact cleaner on the connectors to the computer, idle air control, TPS. If the connector is dirty and has resistance, it can give you troubles.

Don't throw any more parts at it. You need to "test" your way to a solution. Throttle position sensor can be tested with a manual and a meter. You really need to verify this piece of hardware.

It sounds like you may have already checked this solution, and Winterbeater suggested it already, but an extremely overlooked problem a lot of people seem to have is loose battery terminals.

Ive seen at least a half dozen cars get all sorts of crap bought for them when I could just walk up and pick the terminal right off the battery lug! When you have however amount of hundreds of CCA flowing through a connection, that sucker needs to be on there so tight you need a cheater pipe and a thermite grenade to remove.

This is all just my .02, and it probably wont fix your problem, but its free, easy and painless to check and amazingly overlooked item. Good luck with your XJ!

birchlakeXJ said:

Have you ever seen a check engine light? If so, you must pull the codes and see if that can help lead you to the problem.

The problem is definitely not the computer itself (not with 3 replacements) so I would check out the throttle position sensor as scully mentioned and idle air control circuits (including wiring/connectors) pretty closely.

Use electrical contact cleaner on the connectors to the computer, idle air control, TPS. If the connector is dirty and has resistance, it can give you troubles.

Don't throw any more parts at it. You need to "test" your way to a solution. Throttle position sensor can be tested with a manual and a meter. You really need to verify this piece of hardware.

Click to expand...

strickland.thomas said:

It sounds like you may have already checked this solution, and Winterbeater suggested it already, but an extremely overlooked problem a lot of people seem to have is loose battery terminals.

Ive seen at least a half dozen cars get all sorts of crap bought for them when I could just walk up and pick the terminal right off the battery lug! When you have however amount of hundreds of CCA flowing through a connection, that sucker needs to be on there so tight you need a cheater pipe and a thermite grenade to remove.

This is all just my .02, and it probably wont fix your problem, but its free, easy and painless to check and amazingly overlooked item. Good luck with your XJ!

Click to expand...

x3,

you need to find the problem. there must be a an electrical problem if a new/used computers where needed to get it to run fine for a while and then the problem comes back.

test the tps, map sensor, and coolant temp switch along with cleaning ground from battry to block and from head to firewall.

for the cruise control, check the vacumn line and test the brake light switch on the back of the brake pedal arm as it is part of the cruise control curcuit.

Ill check everything. Put the old comp in and the cruse worked, the engine ran bad. Put the new one back in and the cruse didnt work, but the engine runs so much better.

Trust me the battery terminals are good.

Im getting tired of finding stuff wrong and not being the problem.:dunno:

I found a crank sensor wires melted. Cool, i mean its not cool but cool it could be the problem. Went and got a new one for to much money and changed it. I also found a group of ground wires that i mist, cleaned them but the werent that dirty. I also got some eletrical cleaner. Cleaned all the plug ins i could fined. All were clean to begin with. Traced all the wires i could.

Reconnected the battery and started it. Started fine ran good for 5 seconeds spit and sputerd and just quit. Got back inside all the things inside are are still running. Tried to just start it and it started. Stumbled for a sec and was idling fine.

I ran this thing for 20 or so minuts messing with stuff trying to get it to do it agian. I had almost every sensor unpluged. Temps, CPS, MAP, Ox, TPS, and it still kept running. The crank sen was the only one that killed it. I would of freaked if the wouldnt have done it. I couldnt get the problem to come back.

Also on the drivers side fender twards the fire wall. there is this little tan thing that has a wire going to each end of it. When i pull off eather one of these wires the engine dies. I have no idea what this is. Does anyone Know?

I have had so many problems like this that i could change comp and every sensor in the book and still do no good. I really wish i could figure this out.

tan ceramic thing is the fuel pump resistor-- reduces the current to the pump to reduce operating noise. It should die with either wire removed (no fuel)