Topic: need a little help with diagnosing a problem

[gomi]

So this morning I get to go to work and my jeep won't start. I should probably note that it has been cold here and I had not driven her in two days. At the first turn of the key, the engine did not turn over but I could hear the starter clicking. After a few more tries she began to try to turn over but would not start. After work I tried it again and found that if I hold down the gas pedal a little it started up but would immediatley shut off when I took my foot off the gas. After holding the pedal for a minute or two she stayed running, I took her for a drive around the block and noticed that she would idle roughly every now and again while at a stop. Took her back home and she started up normally, but if I pressed the gas pedal to rev it up a bit, when I took my foot off the pedal rpms would dip down very low to the point where she would almost stall. At one point I noticed that she must have lost power because my radio presets and memory were lost. The battery is a year old and the alternator was replaced three years ago. Any ideas? Thanks for any help you boys can give me.

[might4banger]

How cold is "cold"? Could be fuel line freeze up - if it's really freakin' cold out... just a guess.

[gomi]

How cold is "cold"? Could be fuel line freeze up - if it's really freakin' cold out... just a guess.

it's been around lower 20's out, supposed to get colder tomorrow.

[aw12345]

Have the battery tested as well as check the battery cable connections at the battery as well as on the starter and the negative cable at the frame and from frame to engine. Loosing your radia memory settings indicates loss of battery power this will also cause the low idle since the computer has to relearn. Mine does that every time I disconnect the battery for welding

[Jeffy]

Strange that it will start up with the throttle applied.  That's sort of like when the Throttle Position Sensor is disconnected.  Try doing this and see if there are codes.  http://4bangerjp.com/forums/index.php?topic=3419.0

[VA_YJ]

Cold weather tends to kill marginal batteries. Check the electrolyte levels if you can, add distilled water to bring up any cells that are low.  Put the battery on a charger and see if it will take a charge.  If yes, then have it load tested as suggested.  A load tester is basically a resistor that simulates the load of a starter, and you measure the voltage drop as the resistance is applied.  If the battery is good, clean the battery terminals and posts and make sure everything is tight.

When the RPMs are up, your alternator is generating more current, which could be making up for the weak battery.

[chardrc]

id say battery. we had our gc not start this morning. but it was -10 outside.

[Jeffy]

I should also mention if it gets cold enough to freeze take a look at your battery.  Most batteries have sulfuric acid in them.  Sulfuric acid is mostly water and if it gets cold enough to freeze you could see poor performance and it could actually rupture the case of the battery.  You can sometimes see ice crystals inside the battery if it has a opaque case.

Also, since it started I would assume that the battery had enough power to start up.  Once the engine is running, it should be running off the alternator, not the battery.  Since you said it died unless you held the throttle, that make me believe there is something wrong with the Throttle Position Sensor.  If you disconnect it on a otherwise, OK, engine, it will do exactly what you're saying.  Ie., die if there is no throttle input.  Again though, check the PCM/Computer to see if it stored any error codes.  Also take a look at the battery.  You might want to first disconnect the battery and clean up the terminals with some baking soda and a wire toothbrush while you're at it.  Electrical issues can be a PITA and leaving you stranded in winter isn't something you want to happen.

[gomi]

I replaced the battery since it was still under warranty, and she started right up. Has been running like normal ever since so I am hoping this was the problem. I probably should have gotten a better battery to start off with but spent like $40 on it which explains why it probably only lasted a year without problems. Thanks for all of the help guys.

[oldjeep]

I replaced the battery since it was still under warranty, and she started right up. Has been running like normal ever since so I am hoping this was the problem. I probably should have gotten a better battery to start off with but spent like $40 on it which explains why it probably only lasted a year without problems. Thanks for all of the help guys.

Some di-electric grease on the terminals of your new battery would be a good idea, especially if it sits a lot.  It's pretty common on stored vehicles to have no start conditions after they sit for a while due to corrosion.  Taking off the battery cables and cleaning the terminals and cable ends usually solves the problem - coating both with dielectric grease keeps it from happening again.

[dexetr30]

I had a similar problem with having to hold the throttle pedal down but only after my battery was COMPLETELY drained. My wife left the headlights on for 8 hours straight. I think the ecm resets or something similar when the battery is totally drained . I held the throttle down for about 2 minutes at about 1000 r.p.m. I took my foot off the pedal and it ran fine. The battery was pretty shot after that and needed to be replaced. I replaced it with an Optima Red Top.

[gomi]

I was thinking about getting an optima myself, the battery I bought didn't make it for an entire year, but it was a cheapy so.

[Jeffy]

I was thinking about getting an optima myself, the battery I bought didn't make it for an entire year, but it was a cheapy so.

Did they at least replace it for free?

[gomi]

update! Same problem happened again to me yesterday. First key turn nothing, no cranking,power,anything. Then after a few key turns the power and everything slowly begins to get going and if I give her a bit of gas she'll stay running but you have to hold down the pedal for a few minutes. I was late for work so my dad brought her in for me. He took it to pepboys and they told him he needed a new fuel pump, IAC, fuel pump modulator, fuel filter and a few more things. My poor pops went ahead and did it for me even though I told him to wait till I hear back from the boys at 4banger. Total cost.....$1099 wtf! guess what, same thing happened to me this morning so I guess they did not fix it. Took it back and left her for a few hours, just got her back and the mechanic told me he "just hit the switch on the ignition"?? and "it should be okay now". I sort of got upset and told him that that sounded like he did not know what was wrong and got my dad to spend $1099 on nothing. Any ideas??

[Jeffy]

update! Same problem happened again to me yesterday. First key turn nothing, no cranking,power,anything. Then after a few key turns the power and everything slowly begins to get going and if I give her a bit of gas she'll stay running but you have to hold down the pedal for a few minutes. I was late for work so my dad brought her in for me. He took it to pepboys and they told him he needed a new fuel pump, IAC, fuel pump modulator, fuel filter and a few more things. My poor pops went ahead and did it for me even though I told him to wait till I hear back from the boys at 4banger. Total cost.....$1099 wtf! guess what, same thing happened to me this morning so I guess they did not fix it. Took it back and left her for a few hours, just got her back and the mechanic told me he "just hit the switch on the ignition"?? and "it should be okay now". I sort of got upset and told him that that sounded like he did not know what was wrong and got my dad to spend $1099 on nothing. Any ideas??

Yeah, sounds like they just threw parts at it and it happened to fix itself by that time.  I'd check the battery connection again.  How cold is it there?  Overnight?  The clicking is a sign of not getting enough power.  And according to dexetr30, it seems the TJ's don't like drained batteries and start throwing fits.  You might want to check the battery cables themselves to see if there is any corrosion anyplace.  This is a real problem with some cheap batteries with screw on terminals as they tend to vent at the terminals, it eats at the connector.  I think the TJ uses clamps though.  Still a good idea to check.

Oh and what kind of battery do you have?  Pict? might help too.