Brendan Tracy

Hey all, I am new, so please excuse any unintentional faux pas. I have a 94 xj, with a 4.0. I have the aw4 trans. I have been having strange problems with my Jeep. I recently replaced the stock injectors, upgrading to the 4 hole style. After that I reset the pcm, Jeep ran fine for a while then started acting up. It took 30+ seconds of cranking to get it started.also the voltage was down. It was charging, but not as well as it should. Then today my alternator went out. Replaced it, and reset the pcm again, just in case. Turned the key, it fired right up, charging at 14vdc, no problems. Went to turn in my core, turned it off, got back out, fired up fine again. Went to eat, came back out, now it's back to acting up. Took forever to fire up, idle is way low 300 rpm or so. Also charging is back down to 12.8-13vdc. Am I missing something?

jordan96xj

Did you happen to have the battery tested when the alternator went out? The symptoms sound like a low voltage start condition (long crank, rough running, low idle that wants to die unless you keep it alive with pedal).

Perhaps the original alternator died because it was forever trying to charge a bad battery.

2nd up for suggestion is to generally clean up all of your battery and alternator connections and ground connections. Shiny metal, tightly fastened.

Brendan Tracy

I did not test the battery, however I did replace the battery 6 months ago. Has been strong ever since. Also I replaced the starter last month. Cleaned the terminals when I replaced the injectors, did not clean them this time, but that was not to long ago, and they were still shiny today.

jordan96xj

How long was a while in this case? Same day? weeks later?

Brendan Tracy

Similar to this time, ran great for a day or so, then back to ****ty. Thought I might have an injector leaking through killing rail pressure when I turn it off, but I replaced all six again, and checked for leaks, nothing that I could find.

jordan96xj

On this point. That doesn't seem abnormal if the battery was fully charged. So I don't think that will be the issue.

What lead to the original fuel injector replacement? Just hoping to upgrade or were there any problems prior to that?

Brendan Tracy

The Jeep is my Daily, and I drive 100 plus a day. Mainly looking for better mileage, which I have seen, and also better starting. Which I definitely have not.

BlueRidgeMark

IT doesn't take long to kill a lead-acid battery if it's not getting fully charged. You need to have it load tested. Hello, Autozone!



No, that's not right. If the alternator is doing its job, and the engine is running, you shoujld see more like 13.8.

Brendan, have both the alternator and battery tested. I think you're going to find that your alternator isn't getting the job done, and running like that may have killed your new battery. You may also have a parasitic draw. That's easy for you to test, but get the battery and alt tested, too.

Brendan Tracy

No, that's not right. If the alternator is doing its job, and the engine is running, you shoujld see more like 13.8.

Brendan, have both the alternator and battery tested. I think you're going to find that your alternator isn't getting the job done, and running like that may have killed your new battery. You may also have a parasitic draw. That's easy for you to test, but get the battery and alt tested, too.[/QUOTE]
Will do, right now I am planning to switch to an optima, and get the 2 gauge kit to replace all of the main power and ground cables.

BlueRidgeMark

2 gauge is a waste of copper. There is ZERO benefit to it. The factory is adequate at 6 gauge. 4 is a nice upgrade. Anything bigger is doing nothing but wasting copper and money.

If you are talking about relocating the battery to the rear, or adding a battery in the rear, then you should look at bigger.

I went to 4 gauge on the main power to the starter, and main ground to the block, and 8 gauge to the PDC and to the fender inner wall. I also replaced that ground screw on the fender with a 5/16" bolt. I removed the old screw, drilled out the hole, then cleaned around it a patch the size of a nickel. I dropped a nice star washer on a 5/16" bolt, fed it through from the other side, and then a flat washer, another star washer, and a nut. Once that was all tight, I attached my new ground cable and then a star washer, and a nut. All of the hardware is stainless steel, with plenty of dielectric grease at every stage. Works great.

Red1992XJ

Agreed, unless you plan to run a winch, 2 gauge is overkill. 4 gauge is probably where you would want to be, 6 gauge isn't bad, but if you are replacing stuff anyway, 4 gauge usually is close to 6 gauge in price. Get that alternator tested before you put in the optima.

BlueRidgeMark

And that only needs to run to the winch, not the main leads to ground and starter.