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CEL on 2000 XJ after hard starting

U

ultrasam

NAXJA Forum User
Location
Seattle
I bought a 2000 XJ sport from a couple in Milwaukie OR yesterday.

It runs great, smooth and powerful, but starts pretty hard. It turns over just fine, but doesn't fire unless you stop on the gas, then let off it will fire up. Well, I drove it around a bit yesterday in Portland, and after maybe 6 or 7 starts, the Check Engine Light came on. I was already planning on replacing the spark plugs when I get home to Seattle this afternoon, figuring that was probably the likely cause of the hard starting...but I'm a little upset because I just bought it yesterday, and even had it inspected before I bought it, with only the shocks and valve cover gasket being noted as issues.

Where do I start? Anyone have any experience with this sort of thing?

Thanks in advance...Sam
 
lawsoncl said:
Start by pulling the engine code. Autozone will loan you the reader or do it for you.
Click to expand...

The after starting it and stopping it a couple of times this morning, the CEL went off, but I still went to Shucks and got the code pulled...

P0340...camshaft position sensor

I got new plugs and put those in, the old ones were worn looking, but nothing totally whorrible or out of the ordinary. Shucks said it would be 4 days or so for them to order a new camshaft position sensor. So basically I have 2 questions for those who know more than I do..

1: If I'm getting a camshaft sensor fault, replacing the sensor will solve the problem?

2: could this be related to the hard starting?
 
The P0340 fault code is triggered when the computer is getting a signal from the crankshaft sensor for xx number of seconds and nothing from the camshaft sensor. The computer knows the engine is turning but without the camshaft sensor it can't determine which cycle it's on and when to fire the plugs. If the camshaft sensor is weak or failing it will be most noticeable as slower rpms, such as when you're cranking the engine.

If a replacement sensor doesn't cure the problem, I would check the wiring to the sensor for damage and the plug for the sensor itself for corrosion.
 
Last edited:
lawsoncl said:
If a replacement sensor doesn't cure the problem, I would check the wiring to the sensor for damage and the plug for the sensor itself for corrosion.
Click to expand...

I ordered one overnight from RockAuto.com....for under $50. Shuck's wanted $72ish and 3-5 days to order. Thanks for the info guys. It's good to be back in an XJ.
 
lawsoncl said:
If a replacement sensor doesn't cure the problem, I would check the wiring to the sensor for damage and the plug for the sensor itself for corrosion.
Click to expand...


Well, I got the new sensor today, and it didn't seem to cure the problem. I need to have another look at the plug for possible corrosion, but the wires looked fine from what I could tell.

Anything else that could be responsible for such hard starting?
 
Your not getting any coil circuit codes are you? If you look at the cam sensor drive housing (there is a clamp holding it in the block) does it look as though the housing has rotated? If so you would see marks.
 
MJR said:
Your not getting any coil circuit codes are you? If you look at the cam sensor drive housing (there is a clamp holding it in the block) does it look as though the housing has rotated? If so you would see marks.
Click to expand...

I'll have a look tomorrow after work. Thanks for the tip.
 
Does it start any different hot or cold? Possibly the fuel pump is bleeding down when it's off. Fuel pressure should be around 49psi and hold within a few to 5psi for a few minutes afer being shut off.
 
You have a 2000...

therefore, you have no cap/rotor/distributor...you have that coil ignition rail thing...

did you replace that when you replaced your plugs?

Did you disconnect your neg batter cable for about 30 minutes to let the computer reset?
 
Last edited:
P0340 (M)
Camshaft Position Sensor A Circuit (Bank 1 or Single Sensor)
A rationality error has been detected for loss of camshaft position sensor (no fuel sync). Check the camshaft target wheel (located on the right side camshaft sprocket) for damage or excessive runout. The runout is very critical for proper camshaft signal input to the JTEC. The lateral runout on the target wheel should not exceed 0.012 inch.
 
MJR said:
Does it start any different hot or cold? Possibly the fuel pump is bleeding down when it's off. Fuel pressure should be around 49psi and hold within a few to 5psi for a few minutes afer being shut off.
Click to expand...

When warm it usually fires right up, but not always. I guess to test the fuel pump I would need to buy some fancy equipment huh?
 
JNickel101 said:
You have a 2000...

therefore, you have no cap/rotor/distributor...you have that coil ignition rail thing...

did you replace that when you replaced your plugs?

Did you disconnect your neg batter cable for about 30 minutes to let the computer reset?
Click to expand...

I did not replace the coil rail thing...should I? It seems to run fine once it's going.

I also did not disconnect the battery cable, but I wouldn't logic dictate that if the old sensor was bad, and the replacement sensor good, then it shouldn't have the sensor misreadings right?
 
JNickel101 said:
P0340 (M)
Camshaft Position Sensor A Circuit (Bank 1 or Single Sensor)
A rationality error has been detected for loss of camshaft position sensor (no fuel sync). Check the camshaft target wheel (located on the right side camshaft sprocket) for damage or excessive runout. The runout is very critical for proper camshaft signal input to the JTEC. The lateral runout on the target wheel should not exceed 0.012 inch.
Click to expand...

Can you describe the location of said target wheel in relation to the camshaft position sensor? I'm still waiting on my shop manual to arrive. Thanks.
 
So I'm still having this hard starting issue, and I ran the codes again and found none. The guy at Schucks Autoparts said it is probably one of 3 things:

oxygen sensors

egr valve

throttle position sensor

So I found oxygen sensors for about $40 each at rockauto.com, and throttle position sensor for $50 or so, but I can't find the EGR valve...on any websites. I'm getting a shop manual very soon, but until then, i was wondering if you guys could weigh in on what the schucks guy said and help me out with the EGR valve? Thanks!
 
ultrasam said:
So I'm still having this hard starting issue, and I ran the codes again and found none. The guy at Schucks Autoparts said it is probably one of 3 things:

oxygen sensors

egr valve

throttle position sensor

So I found oxygen sensors for about $40 each at rockauto.com, and throttle position sensor for $50 or so, but I can't find the EGR valve...on any websites. I'm getting a shop manual very soon, but until then, i was wondering if you guys could weigh in on what the schucks guy said and help me out with the EGR valve? Thanks!
Click to expand...

the 2000 has no egr valve, only 87-90 have it.
 
McQue said:
not likely that your 02 sensors would cause a hard start problem...
02 sensors are not even looked at by PCM until you are started and they are warmed up...
Click to expand...

if its not the o2 sensors, and not the camshaft position sensor, what could it be?
 
Have you checked fuel pressure with a gauge on the fuel rail during the hard start condition yet?
 
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