2001 XG300 - Major Driveability Problems

[Euro Hillbilly]

*NOTHING IS PREDICTABLE

I have a 2001 XG300 (3.0 V-6) that has a lot of problems. I will try to explain the best that I can. Every issue is random and I cannot find a common cause or time for the problems to occur.


Problems:

• Erattic Idle (In Park and Neutral) - Idle likes to fluctuate and stick anywhere between 1,200 and 2,50 rpm. It stays at the same place and will not jump up or down.
• Low Rpms (In Reverse or Drive) - Revs are very low when put into gear, at a dead stop before giving throttle. Revs are anywhere between 550 and 900 rpms.
• Backfiring Through Intake/Loss of Power (Driving) - When driving at any speed or rpm range, the engine will randomly start backfring through the intake and up into the air filter and then smooth out, then repeat randomly. When this occurs, there is a temporary loss of power causing minor whiplash to the car's occupants from the jerk.
• Over-Advancing Ignition Timing (Idle and Driving) - According to live data form multiple scan tools, at idle, the ignition advance is anywhere between 12 and 18 degrees. At random while driving, it will spike as much as 60 degrees. *No correlation between this and backfiring.

What I have done/replaced:

• Checked and Reset Timing (was not off, but I did take the belt off and redo it just to be sure).
• Replaced Crankshaft Position Sensor
• Checked Spade Sensor Ring for CKPS and everything is good
• Checked Camshaft Position Sensor - Appears to be good. Car will not start without it plugged in. I have no test other than unplugging it to make a decision though.
• Replaced Mass Airflow Sensor
• Adjusted/Checked Throttle Position Sensor
• Replaced Spark Plugs

I mentioned hooking a scan tool up; the car will throw a DTC every now and then. I will erase it to see if the same one pops back up, but it never does. It is always a different code. These codes range from a misfire to ECT to random electrical issues to TPS issues.

*Edit: I don't drive the car anymore. The only time I start it up is when I replace or adjust something. Even if I test drive it, it is never on a road, always on my private property. I don't want to be a traffic hazard.


Any Help is Appreciated. I am planning on selling the car when I get it fixed, if ever. I do not want to lose money on it, but I also do not want to screw the next owner by doing something that is not the correct way.

THANKS EVERYONE!

[Moppie]

G'day, welcome to AF.

Sounds like it's possessed!

It sounds like the computer is throwing a wobbly, might be faulty, or it might be something really simple like a bad ground connection.


I've moved the thread into the engineering technical forum though, we have some pretty experienced mechanics as members, and hopefully one can help you sort this problem out.

It can't be good driving it with spikes in timing, misfires etc. Either for you, or the car.