CPS failure on low mileage vehicle?

[Spudboy]

I have a 2001 XJ, 4.0, Auto. It has 43K miles on it. Ran fine yesterday, parked it overnight, today it won't start. Turns over strong, but no go.

Fuel pressure is 46.5 psi. All fuses are good. Swapped around some of the relays and made no difference. No codes stored. Have not found a test procedure for the coil packs, but I'm assuming I'm not getting spark.

All signs point to a bad CPS but everything I read suggests it should be good to 100K plus. I haven't been able to locate the connector for it so haven't tested it yet.

So, has anyone else run into a CPS that failed at such relatively low miles? Does age matter more than miles?

 

[old_man]

CPS's can fail anytime. I've seen many replacements last only a week. I personally had one that lasted only a month and it was a factory unit.

 

[5-90]

I have a 2001 XJ, 4.0, Auto. It has 43K miles on it. Ran fine yesterday, parked it overnight, today it won't start. Turns over strong, but no go.

Fuel pressure is 46.5 psi. All fuses are good. Swapped around some of the relays and made no difference. No codes stored. Have not found a test procedure for the coil packs, but I'm assuming I'm not getting spark.

All signs point to a bad CPS but everything I read suggests it should be good to 100K plus. I haven't been able to locate the connector for it so haven't tested it yet.

So, has anyone else run into a CPS that failed at such relatively low miles? Does age matter more than miles?

Look toward the rear of the fuel rail and intake manifold to find the connector - it's a three-cavity job with only two wires in it.

And, while you're back there, look down at the CKP. Then look around it. Bear in mind the operating environment - accelerated wear or failure of a borderline part is certainly possible. It's - what? - two inches away from the #6 exhaust primary tube?

 

[Spudboy]

Thanks.

I did look at the back of the fuel rail and only saw a connector for one of the O2 sensors. It's got to be back there somewhere.

 

[birchlakeXJ]

You definitely cannot predict when a component will failure.

Crankshaft position sensor is the primary suspect here.

Without the input signal from the crank sensor to the computer, you will have no spark and you will have no fuel going TO the fuel injectors.

 

[McQue]

2001 XJ CPS SENSOR IS A 3 WIRE SENSOR...+5VOLT, SENSOR SIGNAL, SENSOR GROUND.
LOCATE THE SENSOR ITSELF ON THE FLYWHEEL BELL HOUSING DRIVER SIDE, AND TRACE THE WIRES BACK...I THINK YOU WILL FIND THE CPS PLUG IS IN A VERY TIGHT SPOT AT THE LOWER BACK OF THE MOTOR DOWN LOW ON THE DRIVER SIDE. IT PLUGS INTO THE ENGINE WIRING HARNESS BACK THERE, AND THE HARNESS COMES UP PASSENGER SIDE OF THE MOTOR, TIES INTO EVERYTHING ON THE PASSENGER SIDE OF THE MOTOR, COMES AROUND THE BACK OF THE BLOCK ALONG THE FIREWALL TO DRIVER SIDE TO GET TO THE POWERTRAIN CONTROL MODULE.

 

[Spudboy]

Thought I would update this. New CPS solved the problem.

For future reference for those working on an '01, the connector is on the same bracket as the transmission shift cable (back end of the bell housing on the driver's side). There is a connector for one of the O2 sensors on the same bracket.

Thanks for the tips above.

 

[dukie564]

haven't you heard? It's ALWAYS the crank sensor :shhh: