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It has been doing this for a few months (maybe a ~1000 miles). It only gets driven about 6K per year. It has 123K on it now. I replaced the Plugs and changed the valve cover/plug gaskets a month or so ago mostly because is was leaking some oil onto one of the plugs. That didn't seem to have any effect on the misfires.
While driving at any speed, it runs great. Come to a stop at a light or sit idling a while (less than a min) and it starts missing, whether it is cold or hot.
My daughter drives it to school most of the time and has to sit in a line to get into the parking lot. She's had it completely stall out on her a couple times. One of those times it went into limp mode and the check engine light came on (hadn't been on just from the misfires). Turning it off/on got rid of the limp mode, but the check engine light has now stayed on.
I went to auto zone and they read the codes as P1316 (which I've seen means it is misfiring too much - no duh), P420 and P430 - which I've seen means a "bad" catalytic converter.
I'm thinking that it is not a coil or I'd have problems while driving at speeds.
I've seen a variety of posts on misfires, but most are coil related.
Don't underestimate the possibility of a coil. They do not always fail in a predictable manner.
P0420 and 430 are a somewhat notorious bugaboo on the X300s, at least the early cars. Lots of possible causes and cures....and some anecdotal evidence of them popping up as phantoms codes due to a software type problem.
I battled misfire problems several times on my x300/XJR. usually a coil failure but one time (to cut a *very* long, painful story short) it turned out to be spark plugs....even though the existing plugs were almost brand
new.
As Doug alluded, but did not categorically state, many X300 coil failures are being reported (by Doug and others) with a variety of symptoms. The X300 ECU is known (consent decree with the EPA and all that as proof) to be terrible at identifying misfires correctly. So, a misfire at any temperature or engine speed is POSSIBLY coil related. And replacement is the only sure fire way to diagnose.
I am attaching the 1995 X300 DTC Summaries manual which shows possible causes for all the Diagnostic Trouble Codes.
While the P0420 and P0430 do indicate "Catalyst efficiency below threshold," the cause is not the catalytic converters themselves, but something upstream. The possible causes listed in the manual are:
Exhaust leak (probably ahead of or between the O2 sensors)
Upstream O2S slow response
Upstream O2S sense wire open or short circuit
Intake air leak
MAFS fault
Forgive me for "thinking out loud," but I'm about to head to bed:
The fact that you are getting the P1316 without P0300 and any cylinder-specific P0301-P0306 codes would typically lead us away from suspecting a coil, but as Doug and Ross have already mentioned, the X300 coils don't always trigger the expected codes when they start to get funky.
Since both of your cylinder banks are triggering codes, we can probably rule out the O2 sensors, unless you have leaks at both exhaust manifold gaskets or joints where they meet the downpipes/catalytic converter.
Mass Airflow Sensor problems typically trigger different or additional codes, but its worth carefully cleaning your MAFS with a special zero-residue cleaner spray, both the internal wire and the electrical connector.
Intake air leaks typically trigger additional codes such as P0171 and/or P0174, but not always.
This brings to mind is that cars equipped with PCV valves can develop misfires at idle if the PCV valve sticks in its open position. That makes me wonder if you could have an air leak somewhere in one of the hoses associated with the engine breathing system:
It might be worth checking those hoses carefully for any cracks or other leaks, along with all the vacuum hoses around the intake manifold. And you may as well check all the air intake pipes and fittings for leaks too.
The manual listing for possible causes of P1316 refers us to the possible causes of the P0300 codes, one of which is low fuel pressure, which could lead us to suspect the fuel filter, fuel pressure regulator, fuel pump, etc.. But issues with any of those tend to show up more at high rpms rather than at idle. But if it's been awhile since you changed the fuel filter it might be a good time to replace it just to rule it out as a possible cause or contributing factor (they're widely available and inexpensive).
Regarding the stalling your daughter has experienced, a possible related culprit could be low transmission fluid, which Jaguar has associated with stalling when slowing to a stop or to make a slow turn (the TSB is in the download area, I think).
I looked at all the air hoses and they all look to be in good shape.
The Trans fluid is good also
The PCV valve is the mystery to me. I went to autozone and they tell me it does not have one. I also haven't seen a picture of one online, although Jagbits does say they sell one.
In my experience (not that much), the PCV (PVC?) valve is in the hose that comes out of the valve cover, so I was looking at that, taking it apart and making sure the connections were good. I saw nothing that looks like a PCV vale, but I did see the yellow thing in this picture. It seems to be in the place a PCV usually is, but doesn't look like one to me. Anyway, it comes apart and seemed to be not connected properly (it seals with an O ring). So I put it back together. Things seem better, so that may have been my air leak (although need to drive it more - my daughter will take it to school this week and I'll get her to report back.)
So, my question is: what is that little device? it has a hose at the bottom that goes and connects to the metal tube the Oil dip stick goes in. Seems like a return for extra oil that may come out of the valve cover. The other hose going off to the right, connects with the device in the picture you attached above. What I read is it is some sort of heater (using water from the radiator) to heat the air that passes through?? That device seems to connect to water and air/vacuum hoses. Anyway, I'll report back in a week or so and see if sealing that device properly fixed the issue (btw, it just sort of clicks together)
Since both of your cylinder banks are triggering codes, we can probably rule out the O2 sensors, unless you have leaks at both exhaust manifold gaskets or joints where they meet the downpipes/catalytic converter.
Cracked exhaust manifolds are quite common on X300s and sometime replacing them fixes P0420/430. Sometimes not.
In my experience (not that much), the PCV (PVC?) valve is in the hose that comes out of the valve cover, so I was looking at that, taking it apart and making sure the connections were good. I saw nothing that looks like a PCV vale, but I did see the yellow thing in this picture.
I'm not aware of X300s using a PCV valve. Mine didn't....although I had the supercharged version which might be different
It seems to be in the place a PCV usually is, but doesn't look like one to me. Anyway, it comes apart and seemed to be not connected properly (it seals with an O ring). So I put it back together. Things seem better, so that may have been my air leak (although need to drive it more - my daughter will take it to school this week and I'll get her to report back.)
Possibly #3 in this picture? I dunno....a bit of a stretch....doesn't look quite the same
There was a TSB recommending a change in the breather system design. I can't remember the details. Maybe this widget....whatever it is....has something to do with that?
Sorry if my previous post was confusing. I didn't mean to imply that your car has a PCV valve. It doesn't. On the XJ40/X300 engines the crankcase breathing systems operate without a PCV valve, but since a stuck-open PCV valve can cause misfires at idle on cars that have PCV valves, that led me to wonder if a problem with the crankcase breathing system could cause similar misfires at idle on your Jag.
Regarding that part in your photos, I believe it is the oil separator breather, Part 10 in the diagram below:
Don,
I think it is the #10 in your diagram. I think it was open and I snapped it back together - it has an O ring inside it which I hope seals it. If that was open and causing the breathing system to be open, would that cause misfiring while idling?
It still is misfiring, but a little less than before.
Bob
The fact that the misfires occur while idling certainly suggests an air leak, so I guess the answer must be yes, a leak in that oil separator could be your problem. Did you replace the O-ring you found inside it? If not, it might be worth replacing. If you can't find the right size O-ring and are tempted to try a sealant of some kind, be certain to use a sealant that "sensor safe," since the fumes of some RTV silicones can ruin O2 sensors.
If sealing the oil separator doesn't help, you might look into the ignition coils again. As Doug and Ross have emphasized, problems with coils are very, very common, and failing coils have been known to cause strange, hard-to-diagnose gremlins. It might be worth shuffling your coils to different cylinders to see if you can get get one or more of the P0301-P0306 codes to trigger, which might help you identify a failing coil.
Try spraying WD-40 in the areas where you suspect air leaks. If the idle goes up, chances are you found the air leak. WD-40 is combustible and acts like fuel. So instead of more unmetered air getting into the engine you will be getting more fuel/air mixture, which will make the PRMs go up.
P.S. Always keep a fire extinguisher handy when you conduct these kinds of experiments. Don't ask me how I know this...
I know this thread is kind of old but I am having a similar problem.
I was getting a random misfire code P0300 after changing the VCG, spark plug tube seals, plugs and coils. After inspecting the coils I noticed the pigtail wires for the #1 coil were cracked and touching causing a short. I wrapped the wires and checked for anymore cracks changed the coil and put everything back together.
Now I'm getting a P0301 code I have switched the coils around checked the injectors and the EGR valve. I don't think I have a vacuum leak anywhere. I'm really going crazy trying to chase down this problem. Any Ideas???
A little back story I recently had to drain the fuel tank and lines due to contaminated fuel. I replaced the fuel filter and I thought I had fixed that problem. Could this be related? I would imagine if the fuel was still contaminated it would cause more problems than a cylinder 1 misfire right???
Any help would be greatly appreciated. I want my car back
My first impression is that your most likely suspect is the wiring for the cylinder 1 coil, since you've already noted the cracked insulation and short. Since you've swapped coils and the misfire stayed at cylinder 1, the problem must be upstream of the coil.
If you have a voltmeter, you can check for 12V on the Black/Light Green wire at the coil electrical connector. Whenever the ignition is on, all the coils should have battery power on their BLG wires from the ECM Controlled Relay.
If you have a spark tester that will work with a COP system, you can easily test the cylinder 1 coil for proper operation.
If you don't have a spark tester, try disconnecting the cylinder 1 fuel injector and listen for a drop in engine rpm. If you have a vacuum gauge, you can connect it to a port with constant vacuum and watch for the needle to react when you disconnect the fuel injector. If the rpm doesn't drop and the vacuum gauge needle doesn't move, the coil is probably not firing. Repeat the test a few times to be sure. For reference, perform the test on another cylinder to confirm that the rpm drops and vacuum gauge reacts.
Another possibility is that the ECM electrical connector or circuitry was damaged due to the short in the wiring. The ECM grounds each coil in sequence to fire them, so if you have 12V on the BLG wire, the problem may be in the ground path through the ECM.
A less likely possibility is that the fuel injector for cylinder 1 became plugged during your episode with contaminated fuel.
My first impression is that your most likely suspect is the wiring for the cylinder 1 coil, since you've already noted the cracked insulation and short. Since you've swapped coils and the misfire stayed at cylinder 1, the problem must be upstream of the coil.
If you have a voltmeter, you can check for 12V on the Black/Light Green wire at the coil electrical connector. Whenever the ignition is on, all the coils should have battery power on their BLG wires from the ECM Controlled Relay.
If you have a spark tester that will work with a COP system, you can easily test the cylinder 1 coil for proper operation.
If you don't have a spark tester, try disconnecting the cylinder 1 fuel injector and listen for a drop in engine rpm. If you have a vacuum gauge, you can connect it to a port with constant vacuum and watch for the needle to react when you disconnect the fuel injector. If the rpm doesn't drop and the vacuum gauge needle doesn't move, the coil is probably not firing. Repeat the test a few times to be sure. For reference, perform the test on another cylinder to confirm that the rpm drops and vacuum gauge reacts.
Another possibility is that the ECM electrical connector or circuitry was damaged due to the short in the wiring. The ECM grounds each coil in sequence to fire them, so if you have 12V on the BLG wire, the problem may be in the ground path through the ECM.
A less likely possibility is that the fuel injector for cylinder 1 became plugged during your episode with contaminated fuel.
Cheers,
Don
First off thanks for your help.
I have an inline spark tester and I tested the coil and it was sparking. So my next question is If I have spark on the tester and 12V on the BLG wire could the problem still be in the ground path?
Again thanks in advance for any help in resolving this matter.
Have you tried disconnecting the fuel injector for cylinder 1 while the engine is running and listening for a drop in rpm? If the rpm doesn't drop or change, perhaps the injector is clogged or not operating properly, which is one potential trigger for P0301.
Have you tried disconnecting the fuel injector for cylinder 1 while the engine is running and listening for a drop in rpm? If the rpm doesn't drop or change, perhaps the injector is clogged or not operating properly, which is one potential trigger for P0301.
Cheers,
Don
I did the rpms did not drop. However I also checked the voltage at the green wire on the coil plug and it has no voltage. Does that mean the short fried my ecm? I'm going to try switching the injector to a different cylinder to see if the problem moves.
I crossed my wires in my earlier post. It's the injector harnesses that should have 12V on the Black wires with Light Green tracer lines (BLG color code). The coil harnesses should have 12V on the White wires with Pink tracer lines (WK color code). The Light Green/Blue wire on the cylinder 1 coil is the ground path to the ECM. Sorry I misled you - tired brain.
Did you try disconnecting an injector on another cylinder to see if the engine rpm changed? That might help confirm that the cylinder 1 injector is not working.
I did try the other injectors rmps dropped on all but cylinder 1. I do have 12V on the white /pink wire at the coil. I will check the voltage at the injector today. If the voltage is there my problem is likely a bad injector correct?
I'm sorry to be so difficult but could you expand on the green wire from the first coil (ground path). Should there be voltage to this wire? If so what should I be getting?
I will check the voltage at the injector today. If the voltage is there my problem is likely a bad injector correct?
Bad or possibly just clogged or obstructed. One of our members recently found a piece of debris lodged in the fuel rail above one injector.
Originally Posted by Brandon Wright
I'm sorry to be so difficult but could you expand on the green wire from the first coil (ground path). Should there be voltage to this wire? If so what should I be getting?
You might be able to read an AC voltage - I'm not sure. The voltage on the green wire is the result of the ECM opening and closing the ground path to fire the coil, so it's probably more of a pulsed on-off voltage rather than direct current or a sinewave alternating current.
Thank You So much for your help. Yesterday I pulled the injector and bought a connector at my local auto parts store in a attempt to clean the injectors. It turns out the injector on that cylinder was bad it wouldn't pulse at all. I went ahead and checked the others while I was there. They were all operating properly and now they have all been cleaned and reinstalled with new O rings. The new injector is on its way.
12-08-2015, 10:19 AM
95 VDP misfires while idling cold or hot
