tech question: x300 very rough running...
#1
07-17-2010, 02:40 PM
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tech question: x300 very rough running...
I've picked up a '97 XJ6 and lurked here a bit, but need some experienced answers now.... think you guys can help?
130,000 miles, uncertain mechanical history. I know the throttle body was cleaned out(with regular carb. cleaner) 1-2 years ago, and new plugs. It runs like tea-total crap, idles roughly and wont accelerate over about 52mph. The ck eng. light has produced codes P1315,P0304, P0305,306,300,139, and 0340. These are various and persistent misfire codes for cyls. 4,5 and 6. Code 0139 is for the O2 sensor, bank 1 sensor 2, but I'm guessing thats more of a symptom than a cause here.
The one that concerns me is P0340, for the cam position sensor. I see a crank sensor, but where is the cam position sensor? How is it, and/or the crank sensor and coils tested with a volt/ohmeter? Swapping coils wont be helpful if 3 of 6 are problematic.
There is no oil in the coil cavities causing misfires. Fuel pressure seems adequate and the fuel sample has no water in it.
Engine vacum reads pretty normal, so valve or catalyst problems are unlikely. Vacum is slightly low @ 15psi, so retarded timing seems possible.
Thanks in advance for your efforts! :-)
130,000 miles, uncertain mechanical history. I know the throttle body was cleaned out(with regular carb. cleaner) 1-2 years ago, and new plugs. It runs like tea-total crap, idles roughly and wont accelerate over about 52mph. The ck eng. light has produced codes P1315,P0304, P0305,306,300,139, and 0340. These are various and persistent misfire codes for cyls. 4,5 and 6. Code 0139 is for the O2 sensor, bank 1 sensor 2, but I'm guessing thats more of a symptom than a cause here.
The one that concerns me is P0340, for the cam position sensor. I see a crank sensor, but where is the cam position sensor? How is it, and/or the crank sensor and coils tested with a volt/ohmeter? Swapping coils wont be helpful if 3 of 6 are problematic.
There is no oil in the coil cavities causing misfires. Fuel pressure seems adequate and the fuel sample has no water in it.
Engine vacum reads pretty normal, so valve or catalyst problems are unlikely. Vacum is slightly low @ 15psi, so retarded timing seems possible.
Thanks in advance for your efforts! :-)
#2
07-18-2010, 05:07 AM
I am NO expert on the X300, YET, only what I have established since owning mine.
Keeeping it basic, codes not used for what I say.
Coils are an issue apparently, so a new set may be on the shopping lsit.
The "cam sensor" as such is I believe the pulse generator thingy in the hole where a distributor lived in a previous life. It may be faulty, or mis-timed.
The crank angle sensor, you found that I think, is a suspect after 100k miles, but it usually goes total, not erratic, so the engine just does NOT run.
Really BAD spark plugs, so bad the coils cannot fire them will give your issues.
Injectors not firing, which I THINK is to do with the cam sensor thingy, it sets the seqence of the injector firing order.
Throttle body may be FULL of gunge again after 1-2 years if the engine has been run conctantly with issues.
Getting back to basic steps one at a time are the only way of properly finding the bug/s.
Others will come in with testing procedures for things you requested I am sure, as well as ideas of cause of your issues.
Keeeping it basic, codes not used for what I say.
Coils are an issue apparently, so a new set may be on the shopping lsit.
The "cam sensor" as such is I believe the pulse generator thingy in the hole where a distributor lived in a previous life. It may be faulty, or mis-timed.
The crank angle sensor, you found that I think, is a suspect after 100k miles, but it usually goes total, not erratic, so the engine just does NOT run.
Really BAD spark plugs, so bad the coils cannot fire them will give your issues.
Injectors not firing, which I THINK is to do with the cam sensor thingy, it sets the seqence of the injector firing order.
Throttle body may be FULL of gunge again after 1-2 years if the engine has been run conctantly with issues.
Getting back to basic steps one at a time are the only way of properly finding the bug/s.
Others will come in with testing procedures for things you requested I am sure, as well as ideas of cause of your issues.
Last edited by Grant Francis; 07-18-2010 at 05:10 AM.
#3
08-12-2010, 02:41 PM
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Please, exam all the coil packs carefully for cracks on the coil body and tip. Any crack on the coil will cause an arch between the coil and the block resulting in a misfire. I had the similar problems on my '95 XJ6 VDP about 4 years ago and ended up replacing all the coils. Ouch!!
If you replace your coil pack, it is also a good idea to replace the rubber gasket on the cover. One of the reason for the crack is the water vapor entering this chamber. Buy the OEM coil pack for replacement you will be happy in the long run.
If you replace your coil pack, it is also a good idea to replace the rubber gasket on the cover. One of the reason for the crack is the water vapor entering this chamber. Buy the OEM coil pack for replacement you will be happy in the long run.
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