Stalling...

This usually happens if I stop for coffee and then go back to driving, for example. Big time hesitation on startup, knocking, stall out, the works. Alternatively, it will start relatively normally and then stall under electrical load, not from accessories, or lights, under load from the windows (which will fail to work during these events). Once and if I get it going the problem usually passes...(stalling at 50MPH with no brakes and no power steering is not good) If the problem is occurring silently while driving, I can stall the car by trying to open/close a window at highway speeds. This presented as a grounding problem two days ago, I ran the mains and replaced one fitting, wire brushed the ground contact and the battery terminals. I had backfeed into the running lights and all sorts of whacky things.

I'm also showing a P0705 code and intermittent P0152 (with the knocking).

I had the alternator tested and at 1500RPM it was putting out 30 AMPS, replaced with new 120AMP OEM alternator, problem persists. Battery?

Only mods in the area are a custom mains replacement with welding cable, optima battery and a dual battery system with dedicated house batteries on a diode. I had a headlight plug break with backfeed into the high beam circuit, that was fixed. No other work recently...

I'm thinking battery at this point, and I'm a little ticked at the new alternator sitting under my hood...maybe fuel too?

01' XJ...rocking the YJ until this is ironed out...from toaster to matchbox

Have you resolved your ground issues? That is job #1. Your battery should be LOAD TESTED to determine condition if you are in the least concerned. Load testing is the ONLY accurate way to determine battery condition.

P0152 is the upstream (pre-cat) oxygen sensor. I would investigate the wiring/connector for this sensor and consider replacing it as it is the sensor that the input is factored in for determining fuel/air ratio. How many miles on your oxygen sensors? From my experience, they are generally good for about 100k, some more some less. You can get replacements for under a hondo.

The P0705 could be as simple as the neutral safety switch adjustment (NSS). Pretty common for the automatics. Below is a link to this procedure.

http://www.jpmagazine.com/techartic...eep_cherokee_neutral_safety_switch/index.html

Good advice from BirchlakeXJ.

You aren't getting the cylinder number 3 misfire code--yet--but I find the "if I stop for coffee" comment quite interesting. Do you shut off the engine and go inside or through a drive up?

If you are shutting off the engine, do this--next time you stop for coffee pop the hood and leave it open. Lets see if "heat soak" isn't at least part of your symptoms.

birchlakeXJ said:

Have you resolved your ground issues? That is job #1. Your battery should be LOAD TESTED to determine condition if you are in the least concerned. Load testing is the ONLY accurate way to determine battery condition.

P0152 is the upstream (pre-cat) oxygen sensor. I would investigate the wiring/connector for this sensor and consider replacing it as it is the sensor that the input is factored in for determining fuel/air ratio. How many miles on your oxygen sensors? From my experience, they are generally good for about 100k, some more some less. You can get replacements for under a hondo.

The P0705 could be as simple as the neutral safety switch adjustment (NSS). Pretty common for the automatics. Below is a link to this procedure.

http://www.jpmagazine.com/techartic...eep_cherokee_neutral_safety_switch/index.html

Click to expand...

The groud issues seem to be resolved. Like I said, I ended up preping the ground surfaces and replacing a connector on the battery neg. to ground cable that I wasn't 100% happy with. That solved some of the ground issues (back filling of the lighting circuits) but not the main problem.

One of the contacts at the battery isolator was loose as well (alternator power input). Since fixing that I have not been able to reproduce the problem, but given the nature of this issue...that doesn't really mean much.

When it stalls, I always have power to crank.

The O2 sensors have around 100K on them but I believe that the P0152 is a product of the stall not the cause of it. I have had O2 sensor codes before when knocking which usually happens when it gets its monthly fill of premium fuel (which it had ~Tuesday). I got this code yesterday during a stall, cleared it and have only seen it once through this whole ordeal. The P0705 is new and uniqe to these events.

joe_peters said:

Good advice from BirchlakeXJ.

You aren't getting the cylinder number 3 misfire code--yet--but I find the "if I stop for coffee" comment quite interesting. Do you shut off the engine and go inside or through a drive up?

If you are shutting off the engine, do this--next time you stop for coffee pop the hood and leave it open. Lets see if "heat soak" isn't at least part of your symptoms.

Click to expand...

I usually get a misfire and the O2 sensor error with premium gas...essentially after short stops and restarts, never any issues while driving though, and the windows and their envolvement is beyond me...

the more I get into this the more I want to get my old alternator back to test at another shop...

Hood down on a good soak from a drive around the block and it is still reproduceable. The thing that is bothering me is all the funny colors and patterns my rear running lights make during one of these episodes.

Vehicle running, knocks and stutters when operating windows and when attempting to move. High RPMs do not solve the issue, but if I can ride out the stutters it eventually kicks in and works just fine. Vehicle off, 12+ volts from the battery, which is just enough to roll one window up at a time but it kills the interior lights. I'm back to defective replacement alternator, but the rear lights seem like a ground issue to me...

Remove/isolate the second battery.

Post up what happens.

joe_peters said:

Remove/isolate the second battery.

Post up what happens.

Click to expand...

The second set of batteries, two Optima Blue Tops in the trunk are fed off the isolator in the engine compartment, it drops the voltage to the primary battery by about .75 volts and always has. They are completely isolated...are we thinking that heat soak to the diode is causing a current drop? I can bypass the whole thing...

I tried taking a short drive, sitting hood up 10 minutes, no problem; short drive, hood down 10 minutes; no problem...its now sitting for 30 and I'll try it again. I can't seem to reproduce the issue now.

Nothing on the 30 minute soak, but its about 30 degrees cooler outside now. I can't get it to reproduce. This has to be a heat issue.

Well, 99-01 XJs there is a TSB on the heat soak problem. Seem that the problem is more pronounced if you have the 50 state emissions package--two mini pre-CATS in the exhaust manifold--but does present in all XJs made during those years.

Toss in ethanol and hot days--perfect storm.

TSB fix is a wrap for the number three injector. Some (most) have no luck with it, runs about $8 at the dealership.

IF leaving the hood open eliminates the some of your symptoms, consider adding a timer to the aux fan to run it for about 5 minutes after the engine shuts off. Sample timer: http://www.at-fairfax.com/P1786-ELK-960.htm

I wanted to see if disconnecting the extra batteries reduced some of your symptoms.

There is a TSB for 99-01 XJs (99+ 4.0s, all of them) for heat soak. TSB fix is to insulate the number 3 injector--works for some, but not all. If you have the 50 state emissions--two mini pre-CATs in the exhaust manifold--it might not work for yours. Toss in ethanol and hot weather, its kind of like the perfect storm for heat soak.

Here is a timer you can put in for the aux fan to have it run for about 5 minutes after the engine shuts off: http://www.at-fairfax.com/P1786-ELK-960.htm

joe_peters said:

Well, 99-01 XJs there is a TSB on the heat soak problem. Seem that the problem is more pronounced if you have the 50 state emissions package--two mini pre-CATS in the exhaust manifold--but does present in all XJs made during those years.

Toss in ethanol and hot days--perfect storm.

TSB fix is a wrap for the number three injector. Some (most) have no luck with it, runs about $8 at the dealership.

IF leaving the hood open eliminates the some of your symptoms, consider adding a timer to the aux fan to run it for about 5 minutes after the engine shuts off. Sample timer: http://www.at-fairfax.com/P1786-ELK-960.htm

Click to expand...

I've had heat soak before for sure but all of these electrical symptoms are new...especially the 30 amp max output from the alternator (not sure if pre or post isolator). I'm wondering if heat might be getting to the isolator?

the low voltage in acessory position says battery or downstream from the battery though...

Turns out the Transmission Range Sensor (P0705 code) and the headlights share a common ground point on the left (D/S) engine bay. Backfeed from the headlamps illuminated the high beam light (dimly) on the dash. The ground points were questionable so they got buffed up. I have to wait until dark to make sure the headlamp light is off, but it appears to be at this point. I also ran a ground from the heatsink on the isolator to the negative post. I am unable to replicate the problem today, I don't think it is hot enough outside.

I also bypassed the second battery system and isolator but as I cannot replicate the problem results are inconclusive and I'm going to go back to the origional configuration until I can replicate the issue.

Pulled the aux. fan fuse and got it hot enough to cause 4 different emissions errors, the temp gauge sensor to go nuts and the usual heat soak rough start and run but NO electrical symptoms whatsoever...

I need to load test the battery, but I cut out the alternator and ran on battery for a few minutes without a hiccup...