Same Jeep different problem

daveswaves · Dec 30, 2003

Re: Same Jeep different problem

My experince with a Jeep Cherokee( 340,000 km) would lead me to check the tps voltage and make sure it is "smooth". Use an analog meter, not digital, and monitor the TPS output at the connector. Look for "dead spots", especially around the beginning of your throttle travel. Voltage swing is theoretically from 0 to 5V, in practice it will not be 0, probably around .6 V and will swing up to 4.7 V or so. There are three wires coming out of the TPS, can't remember the colors off hand but one pair will swing from 0 to 5 the other combination (using the center wire common to both) will swing from 5 to 0. One side "talks" to the Transmission control module and the other "talks" to the ECM. With all the mail box starts and stops the TPS gets extra wear.

daveswaves · Dec 30, 2003

Re: Same Jeep different problem

SBN, one more thought, you mention the engine RPM is changing by 300 to 400 rpm as you are going up hill. Could also be the torque converter locking and unlocking. TPS will do this as well.

SpinnerBait_Nut · Dec 31, 2003

Re: Same Jeep different problem

Thanks again daveswaves, but what has me puzzled so much is why it takes so long for it to screw up. Like something is getting heated up and breaking down. I know I am about to have a breakdown.

oddjob · Dec 31, 2003

Re: Same Jeep different problem

SBN, I bought the same Jeep 96' (148000mls)as you 3 months prior. Runs great except when I run on the highway about 2-3 three hours. Almost as soon as I get off it does the same thing your describing. If I fight it ,it gets worse. Then I just trottle down for a moment and the problem disappears until I make the same trip again. I have a brand new distributor, points and plugs etc. Ive never had a problem driving around town unless I "drive it like I stole it- flahthead " for more than a half an hour. It does appear to be heat related along with what has already been stated. Anyway, I'm pulling for ya as I would like to resolve the prob as well. Sorry I didnt give any advise to this thread, but I just wanted to let you know this sounds like a common problem that requires major throubleshooting to resolve.

daveswaves · Dec 31, 2003

Re: Same Jeep different problem

SBN you are right in thinking it may be heat related. the TPS gets a lot of heat from the exhaust manifold. They sometimes develop a crack in the resistance element (carbon) Often happens after your hose down your engine in a car wash when hot.

SpinnerBait_Nut · Dec 31, 2003

Re: Same Jeep different problem

Yea, it has no problem out on the interstate. I set the cruise at 70 and sit back and went on. It did not show up till after I got off and yes OJ, it seems to not help at all to mash it on down, just more of an RPM fluctuation. I have never hit the engine with water, but can't say what went on before I got it though.

LubeDude · Dec 31, 2003

Re: Same Jeep different problem

As we get older, and we spend too much time on our boats sitting on our A**s the muscles in out legs get soft and it makes it harder to hold a steady preasure on the throtle! I wouldnt worry about it any more!

LubeDude

Elmer Fudge · Dec 31, 2003

Re: Same Jeep different problem

Hi SBN, I had a similar problem with an 1986 volvo 240DL and just like Skinnywater said it turned out to be the Air flow mass sensor. Also while the motor is on, fiddle with the fuses,it may possibly be something easily overlooked, like a loose connection on a relay fuse. I hope that this problem don't end up costing you a bundle, what a bummer that would be.

SpinnerBait_Nut · Dec 31, 2003

Re: Same Jeep different problem

Again, I want to thank everyone for the replies and info. I talked to the Jeep dealer's service department and they assured me they could find out what was wrong for $70. I think I will save myself some time and money and let them tell me what's wrong. I will let you know as soon as I find out. Maybe tomorrow.

SpinnerBait_Nut · Jan 3, 2004

Re: Same Jeep different problem

Update; Well found out a couple things. 1) My Jeep is a change over Jeep as in a late '96. Found this out when went to buy a CPS for it. All the parts houses had one for a '96, but was different than mine and they did not have it so, had to go to dealer and after giving him my last 6 digits of my VIN, they told me that it was a change over model and it took a different CPS. Well after $122 and change, no different. Now here is some more ammo for you fellows to see if you can figure it out. It was warm here this am and I was riding around with my windows down. I noticed a faint smell of gas and right after that, it would start running bad again. This time I mashed the gas a little more and it would backfire through the intake it sounded like. Now another clue, I could stop, turn engine off, count to 5, start back up and run like a champ for about 20 minutes or so and it would do it again. Again, I would shut it off and start it back and it would run fine for a little while and right back to the problem. Each time it would do this, I could smell some gas fumes right before it acted up. Please help, I am out of options on this thing.

SpinnerBait_Nut · Jan 3, 2004

Re: Same Jeep different problem

I forgot to add, it is now storing a code 11 which is where it detected when I had the CPS loose. I tried to start it without it plugged in(DUHHH) Would this somehow cause it to do this? After I had put the new CPS on, it ran like a raped ape, no hesitation at all. Would lite the mud tires up. Then when I used it on my run this am, it started that stuff. Just wondering if maybe the code 11 has something to do with it. EDIT: ODDJOB, hang in there. I will find the culprit yet if my money holds out.

daveswaves · Jan 3, 2004

Re: Same Jeep different problem

Let me guess, the dealer said "must be the cps" cause they couldn't find anything else

Other fuel related weird things could be O2 sensor or fuel pressure regulator on the fuel rail. Edit: SBN, the code 11 is because it did not see a crank signal, however, if you had your battery disconnected while you were doing this, which you probably did, the ECM and the TCM will have defaulted to a default value. The engine may be starting itself off "rich" could explain the gas smell and then learning itself lean again. Still could be O2 sensor.

SpinnerBait_Nut · Jan 3, 2004

Re: Same Jeep different problem

Dealer said leave it for 3 days and we will find problem. Regulator is not on fuel rail, it is on top of fuel pump. I have replaced both 02 sensors with new one's.

SpinnerBait_Nut · Jan 4, 2004

Re: Same Jeep different problem

Update; Could it be possible that the coil is heating up and breaking down? The reason I ask is that this morning while out on my run, it started it's stuff and the check engine light came on this time and after I got back home, check the code and it is a #43 which is; "Peak primary coil current not achieved with max dwell time or Cylinder misfire", which could be caused by the coil if I am correct. Anyway, I am going to put one on and see. Will let you know the outcome. I will solve this mystery yet if I don't run out of money first.

SpinnerBait_Nut · Jan 4, 2004

Re: Same Jeep different problem

Ok, another update. Man this is killing me.

I put new coil on and ran it for about an hour or so and it ran like showroom. Uphill and down no problem. I was just driving like a normal person. I stopped on the way back, romped on it real hard, the mud tires came to life for about 5 seconds

, and then it fell on it's face. I let up on the gas and it went on. Now the only problem I have is when I crowd it real hard, it will bog down till I let up on the gas and then it will run like normal. I know what I should do and that is to bomb it, but I really like it and I will get it fixed, but I think I have the most of it whipped now. Will keep you updated. P.S. oddjob, shoot me an email when you get time.

Boomyal · Jan 4, 2004

Re: Same Jeep different problem

It's the main computer. Take it to the dealer. It's a Chrysler system.

SpinnerBait_Nut · Jan 4, 2004

Re: Same Jeep different problem

Another update: This one is a good update. It might also be a duhhhh!!!! I bought this Jeep in October and ever day it has got gas at the same place, 7.5 to 8.6 gallon, ever day, even the very first day I got it. Well, this morning I took it with me on my morning run and it had about 1/4 tank in it, so I decided to go to that special place and get gas but it started really acting up on me, so I thought well the gauge might be a little off and I did not feel like calling wifey poof at 1 in the morning to tell her I had run out of gas, so I stopped at another place and filled her up with good ol hi-test, dumped in a couple bottles dri-gas, and took off. Ran like a champ all the way and back on my 6 hour run. It did still have some hesitation to it, but I think that maybe it don't like the gas at the other place. It is a big chain (FlyingJ) that I would get it at so I figured their gas would be good, but I guess not, but will be sure tomorrow cause he will use it today and I will take it with me again tomorrow to see. All I can say is it is another 100% better than it was yesterday.

oddjob · Jan 5, 2004

Re: Same Jeep different problem

Hey SBN, sorry I havnt gott'n back till now,I havnt been around for awhile. Maybe I should change to high test for a while. I've never noticed the gas smell though. I hate electronics on cars,

Its a deliberate rip-off scheme designed by mfg. I hope to hear more good news from ya, good luck.

SpinnerBait_Nut · Jan 5, 2004

Re: Same Jeep different problem

oddjob, the gas smell was coming from a faulty gas cap. One of many items that is new now.

Does your check engine light ever come on? Have you ever pulled the codes yourself? Let me know, I am getting to be an expert on these critters now.

Boomyal · Jan 5, 2004

Re: Same Jeep different problem

Originally posted by Boomyal: It's the main computer. Take it to the dealer. It's a Chrysler system.

Same Jeep different problem

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