4x4JeePmaNthINg
NAXJA Forum User
- Location
- Colorado
Check engine liget came on today and the code is for the battery temp sensor. Could this be a culprit rather than bad gas?
Check engine liget came on today and the code is for the battery temp sensor. Could this be a culprit rather than bad gas?
the battery is very new, Interstate. I replaced it when my alt died because a few weeks later the battery lost too many cranking amps.
I checked the sensor and its plug which all seemed fine. I can get the battery/ starter tested however if ive never experienced these symptom pre/post occurence would you still think i should get these items tested? I havent had a hickup since.
Then I would stop by the place you bought them and have them use a tester on the running rig, and test the battery and starter for capacity and load.
I have a multi meter but what is ment by checking for load and capacity? also why am i checking the starter?
Then I would stop by the place you bought them and have them use a tester on the running rig, and test the battery and starter for capacity and load.
I have a multi meter but what is ment by checking for load and capacity? also why am i checking the starter?
Bad alternators can damage a battery, and a bad battery can damage a starter or an alternator, or voltage regulator (Old rigs it was in the alternator, new models it is in the PCM computer)..and a bad starter can damage a battery. By bad starter I mean one that is partly shorted internally pulling too much current, but still seems to be working with a fresh battery.
With a volt meter you have some one crank the engine, while you monitor the battery post to post voltage. If it drops under 10 Volts while cranking, something is wrong. BY testing the voltage you are testing the coupled battery-starter system. If the voltage drops below 10 volts, it does not tell you which part is bad. The stores can load test the battery by itself with a resistor pile in their tester to see which is the problem.
Your first thoughts on a vacuum issue may be right, it could also be a marginal O2 sensor system, where the sensor gets too cold at idle and switches to open loop, that could be a blown fuse, damaged sensor wire (they damaged easily due to their locations), bad relay on the older XJs, or bad heater in the O2 sensor. That too can be tested with a volt-ohm multimeter. The dip in idle and recovery is from the PCM switching from closed loop to open loop mode.
The PCM changes the IAC (Idle Air Controller) setting-air feed rate to manage the air to fuel ratio in response to the O2 sensor data. So if the IAC is not sticking, id look at testing the O2 sensor system, wiring, fuse, and sensor..
Here is a how to thread on O2 sensor testing
http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+sensor+test
both upstream and downstream O2 sensors are bosch and less than 3yrs old. for whatever reason this issue is only after a good drive then sitting idling for a while. the only other issues since are the battery temp sensor code that went away same day.
Ill continue to inspect your recommendations and update whats going on.
If it is vacuum how can i test the lines? tried smoke but saw nothing- probably not the best test. Ill pull the TB this weekend and clean IAC/ inspect tps.
I haven't tested fuel pressure since I upgraded the injectors a couple years ago. She fires up instantly so I don't think it's pressure related. I think it was 49psi at the rail with very slow bleed down after turned offrom, never below 35.
......? well you postednever mind. question already answered....
That sounds more like a heat soak and or fuel pressure leak down issue after the pump/engine is turned off problem to me.
So today i got to work early and i let the car run while i listened to the stereo. I got the same symptoms of rough idling like a consistent misfire after 15-20 minutes of sitting idling. I have brown dog motor mounts/ straight pipe so when this happens its very noticeable.
After peeking around in the engine bay i have found my second from the grill cylinder/ exhaust manifold tube has a large crack. My theory is that at idle the heat is building through the intake and causing the previously mentioned heat soak. the crack is maybe like an inch+ on the out side of the exhaust tube.
what say you, good bet?
also this is not my stock manifold and is an oem replacement with the accordion looking flex areas, off topic, but im open to new replacement recommendations.