Hi - I have a 95 X300 Xj6 - yesterday i went for a run mid afternoon - maybe 17c and did not miss a beat. I had just checked for codes OBD2 and none. Went out at night and returned home 9pm - ambient temp maybe 5c - car stalled all the way home (short distance only). I ran in the drive for a while and continued to stall - intersting was the door lock lock and unloced as if it was driving. Anyone got an clues. Ill check the Intake air sensor today nad have just repalced the coolant temp sensor. Lock mechanism activating makes me think of road speed ? Any hjelp appreciated. Matt

further info. Have checked coolant and input air temp sensors, TPS and MAF and all good. Removed and cleaned camshaft and crank sensors and seem to be good. All this seems to have improved situation to point car does not totally stall now just hesitates and then runs again. On the OBD2 I do notice the voltage goes down to about 13.2 but cannot tell whether this is because the car is stalling or the cause? Is it possible to have a temp related curcuit issue like a fuse that is separating when cold?

 

Other then the voltage going to 13.2 during one observation you are still above a fully charged battery so we'll leave that alone for now

We will look at the power to the engine ECU as there are 2 sources

Right engine bay fuse box relay # 9 ( relay can be swapped from the left engine bay fuse box relay # 7 which in reality only runs the car horn )

Large ECU controlled relay ( right # 5 ) which is controlled by the ECU and brings power back into the ECU ( this can be swapped with the same part # relay in the area like the fog , headlight , A/ C clutch )

The large relays can be hard to separate without some penetrating oil as you flip them upside down

Your security door lock cycling may be related to the right engine fuse box relay without researching

Marked the crankshaft harmonic balancer pullies for separation ?

 

Thanks all for advice - I have found two problems that I think I need to fix and maybe related

1: The fuse panel in the rear trunk connector bolt to the large cable is loose and I susepct a poor connection. This provides power to the BCM so maybe that is linked and could explain strange locking and unlocking of doors with stalling? I understand that the BCM also powers the ignition circuit ???

2: I removed and cleaned all terminals for the Crankshaft Position Sensor - when re-intalled the car did not stall just hesitated - lost RPM and voltage but continued running and then recovered back to idle speed. Does this suggest a faulty Crank PS? If the Crank PS is faulty and not sending signal would that cause the car to stall as it has no reference to firing cycle ? I am guessing that no signal for a second or so could cause a stall based on the fact the car will not start without Crank PS?

Cheer All

Matt

 

The CKPS single signal in the 2 wires is used in fuel pump enable , spark timing , injector timing , RPM gauge

Any of these can fail to be seen properly in these 4 areas without giving a CEL code

Both relays mentioned above can also be intermittently failing

The BCM enables starter motor engagement and rotation , not so sure on after that point in engine starting sequence off the top of my head

The door lock cycling could be from the security lock control unit which is powered through the trunk fuse box terminal post and the dedicated fuse in the row is hot at all times

The engine will defiantly stall with a loss of the CKPS , It will start with a faulty Camshaft position sensor and only rely on the Crankshaft position sensor and takes more starter revolutions

The loss of RPM and voltage at the same time points to the instrument cluster possibly not being powered , it's power comes through a fuse in the left heelboard fuse box and the associated fuse box relay ( also referred to as ignition positive relay , there being 2 ) in the corner being intermittent . It can be swapped with the same left engine bay fuse box relay ( horn )

 

Hi all - update on this issue (or issues I think now - still suspicious of Crank Sensor) - further analysis using OBD2 has identified that my LTFT is -85.2 on both banks and does not move at all while STFT seems Ok. This says to me that there is way more fuel than required or less air being delivered. Throttle body is all clean and appraently working fine. TPS and MAF seems to output correct voltages so I am left thinking either fuel pressure regulator putting in to much fuel or both O2 sensors upstream - but having the same -ve LTFT seems a little suspicious and suggests a signle component rather than both O2's going out exactley the same. Anyone had such high -ve LTFT and worked out the cause ?

Cheers Matt

 

Try swapping the O2 sensors around at the connectors.

 

I had green corrosion on the rear O2 sensor connectors

The shielding wire grounds for the O2 sensors are the small terminal post on the rear firewall

Missing washers on the sensor installation in the pipe bosses seems to have an effect

The washers can be obtained from a cheap copper spark plug box

 

Thanks for reply - Do you mean upstream or downstream ??