Misfire Issues
#61
#62
Join Date: Sep 2008
Location: Damon /Houston, Texas
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A dirty throttle body causes 2 things, poor idle, and stalling both at idle and when on the freeway and you take you foot off the gas. What happens is there is no longer a mechanical air bypass past the throttle blade, and the idle air control solenoid in the throttle body which is normaly just as dirty, cannot comphensate fast enough. Clean not only the part load breather, but the throttle body bore and air bypass port(drilled port just above the throttle blade that comes out just below it.
#63
#64
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Garbage In = Garbage out
Ambient Air -> MAF sensor -> IACT sensor -> Data to the PCM
Accelerator pedal sensor -> TPS sensor -> Throttle body control -> Data to the PCM.
(Air/Fuel mix - less air) + EMISSIONS!
The wrong data to the PCM can cause a misfire.
A stuck,broken,or a slow electronic throttle plate will make the engine run rich in fuel.
Was the MAF & Throttle body replaced because of Frnt-end Accident, or Troubleshooting @ customers expense?
Ambient Air -> MAF sensor -> IACT sensor -> Data to the PCM
Accelerator pedal sensor -> TPS sensor -> Throttle body control -> Data to the PCM.
(Air/Fuel mix - less air) + EMISSIONS!
The wrong data to the PCM can cause a misfire.
A stuck,broken,or a slow electronic throttle plate will make the engine run rich in fuel.
Was the MAF & Throttle body replaced because of Frnt-end Accident, or Troubleshooting @ customers expense?
Last edited by danielsatur; 10-12-2009 at 12:09 PM.
#65
#67
#68
Many thanks to Brutal for taking the time to be as detailed as he has been in this thread. If and when the P303 misfire code pops up again, both Brutal and Rick have convinced me that the best possible action for me to take would be to go ahead and replace the two Intake Manifold Tuner O-rings with the new-style green-colored ones. I'll spring for new upper intake manifold gaskets as well - why risk not doing so? And I think I'll also go ahead and put in a new set of NGK iridium spark plugs. I've determined that my factory plugs are Motorcraft iridium plugs. That makes sense with the engine being essentially a modified Ford Duratech V6. The only thing I hadn't thought of that Brutal mentioned is to go ahead and replace the cylinder 3 coil. I haven't decided on this yet. Remember - when the cylinder 3 misfire (code P303) first appeared in early September, that coil was supposedly swapped with cylinder 2. Well, we had another cylinder 3 misfire (code P303) occur on October 2nd. If a bad coil is indeed the culprit, my thinking is that cylinder 2 should have been the one that misfired and threw a code P302 and turned on the "check engine" light. And that did not happen.
After thinking about and studying all this information for more than a week now, I think that Brutal and Rick have presented the best approach to me by replacing the Intake Manifold Tuner O-rings. Even my dealer's service department has recommended that this be done. And of course, they want to do it at my expense. But I'm leaning towards taking up Rick's generous offer for me to drive the car to his house (3 hours away) and the two of us will do the job in his driveway and get a chance to meet for the first time. That's a lot more appealing than continuing to pay a dealership that just wants to sell me multiple services with no actual diagnostics confirming that those pricey services will actually fix my misfire problem once and for all.
But unlike Rick's car back in March of this year, I'm not seeing or feeling any oil leaks down on the bolts or under the tuners. I don't think I'm hearing any vacuum leaks either, but I will continue to look for oil residue and listen for hissing sounds under the hood. But if our S-Type throws this same P303 code again in the weeks or months ahead, I think I'll order the gaskets and O-rings, pick up a set of NGK iridium spark plugs, confirm with Rick, and head down to his house at his convenience. I think we'll have a great time together and fix this S-Type's misfire problems all at the same time !
Additional information that may prove to be important for our particular car: The entire Throttle Body is new (May 2009), the Mass Air Flow sensor is new (October 2009), and the Air Filter Housing and Air Filter Element are both new (October 2009).
Other opinions and recommendations on this topic are always welcome. Those of us with the original Intake Manifold Tuner O-rings (which I understand are yellow in color) may all be dealing with this issue in the near future. I wonder what contributes most to the failure of these yellow O-rings - age or mileage?
After thinking about and studying all this information for more than a week now, I think that Brutal and Rick have presented the best approach to me by replacing the Intake Manifold Tuner O-rings. Even my dealer's service department has recommended that this be done. And of course, they want to do it at my expense. But I'm leaning towards taking up Rick's generous offer for me to drive the car to his house (3 hours away) and the two of us will do the job in his driveway and get a chance to meet for the first time. That's a lot more appealing than continuing to pay a dealership that just wants to sell me multiple services with no actual diagnostics confirming that those pricey services will actually fix my misfire problem once and for all.
But unlike Rick's car back in March of this year, I'm not seeing or feeling any oil leaks down on the bolts or under the tuners. I don't think I'm hearing any vacuum leaks either, but I will continue to look for oil residue and listen for hissing sounds under the hood. But if our S-Type throws this same P303 code again in the weeks or months ahead, I think I'll order the gaskets and O-rings, pick up a set of NGK iridium spark plugs, confirm with Rick, and head down to his house at his convenience. I think we'll have a great time together and fix this S-Type's misfire problems all at the same time !
Additional information that may prove to be important for our particular car: The entire Throttle Body is new (May 2009), the Mass Air Flow sensor is new (October 2009), and the Air Filter Housing and Air Filter Element are both new (October 2009).
Other opinions and recommendations on this topic are always welcome. Those of us with the original Intake Manifold Tuner O-rings (which I understand are yellow in color) may all be dealing with this issue in the near future. I wonder what contributes most to the failure of these yellow O-rings - age or mileage?
Last edited by Jon89; 10-12-2009 at 10:28 AM.
#69
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#70
Join Date: Sep 2008
Location: Damon /Houston, Texas
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well the old adage holds true in this case. "SIZE MATTERS!" the yellow are slightly smaller than the green and that green coating on the black oring seals to the intake, theyre very hard to remove once they set. And its not so much a matter of a vacuum, or oil leak but also a chance to install updated known improved orings and CLEAN THE OIL FROM THE LOWER INTAKE OPENING WITH THE IMT REMOVED. I personally would spend the money on a couple coils over new upper intake orings(not the IMTs but the intake seals) and theyre probobly cheaper
#71
Brutal,
I thought your misfire theory centered around these factory (yellow) IMT O-rings failing, thereby allowing blow-by oil into the cylinders (primarily cylinders 1, 3, and 5), and thus causing the misfires that I'm getting along with other S-Type owners who are experiencing this same problem.
Now you seem to be saying that you would just replace a couple of coils instead of replacing the factory (yellow) IMT O-rings when you already know they create blow-by oil problems in the cylinders.
What gives?
I thought your misfire theory centered around these factory (yellow) IMT O-rings failing, thereby allowing blow-by oil into the cylinders (primarily cylinders 1, 3, and 5), and thus causing the misfires that I'm getting along with other S-Type owners who are experiencing this same problem.
Now you seem to be saying that you would just replace a couple of coils instead of replacing the factory (yellow) IMT O-rings when you already know they create blow-by oil problems in the cylinders.
What gives?
#72
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COP - Coil check
COIL Check
http://www.automotiveforums.com/vbul...d.php?t=906504
Spark plug Boss seal leak
http://www.automotiveforums.com/vbul...d.php?t=893206
Oil check
http://www.automotiveforums.com/vbul...d.php?t=948190
http://www.automotiveforums.com/vbul...d.php?t=906504
Spark plug Boss seal leak
http://www.automotiveforums.com/vbul...d.php?t=893206
Oil check
http://www.automotiveforums.com/vbul...d.php?t=948190
#73
#74
Join Date: Sep 2008
Location: Damon /Houston, Texas
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Brutal,
I thought your misfire theory centered around these factory (yellow) IMT O-rings failing, thereby allowing blow-by oil into the cylinders (primarily cylinders 1, 3, and 5), and thus causing the misfires that I'm getting along with other S-Type owners who are experiencing this same problem.
Now you seem to be saying that you would just replace a couple of coils instead of replacing the factory (yellow) IMT O-rings when you already know they create blow-by oil problems in the cylinders.
What gives?
I thought your misfire theory centered around these factory (yellow) IMT O-rings failing, thereby allowing blow-by oil into the cylinders (primarily cylinders 1, 3, and 5), and thus causing the misfires that I'm getting along with other S-Type owners who are experiencing this same problem.
Now you seem to be saying that you would just replace a couple of coils instead of replacing the factory (yellow) IMT O-rings when you already know they create blow-by oil problems in the cylinders.
What gives?
and oil leaks. The cam gaskets many times get blames for oil leaking on the exhaust and changed and not the IMTs. I have opened up intakes to replace imt orings and literally had oil pour out all over the exhaust. Is there a permanent fix? not from Jaguar, sometimes it just is what it is and would take maybe a redesign(wont happen) of the intake/engine. new engines are already out and time marches on...Of course these are all just my hypothesis, and maybe dont amount to more than thinking out loud. I just know what I do in these situations I have have very few recheckes for this issue. They do return, but is usually a few years down the road. about the same your seeing on a 3-4 year old car.
you know maybe someone could drill and tap the intake right there, install a line and catch can that would hold vacuum and could catch the oil and drain it out. Then you could market it on Ebay and retire in the Bahamas....
#75
#76
It is my understanding that Ford did NOT install any Intake Manifold Tuners in its Duratech 3-liter V6 engine that it placed in Ford cars. If the Intake Manifold Tuner is such a problem-causer with vacuum leaks and oil leaks on many if not most of the Jaguar cars that use this modified Duratech engine, why did Jaguar opt to include IMTs and create more problems by doing so?
#77
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Location: Damon /Houston, Texas
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it is my understanding that ford did not install any intake manifold tuners in its duratech 3-liter v6 engine that it placed in ford cars. If the intake manifold tuner is such a problem-causer with vacuum leaks and oil leaks on many if not most of the jaguar cars that use this modified duratech engine, why did jaguar opt to include imts and create more problems by doing so?
it is one thing that really makes the engine behave like two different power plants. That and vvt's
orings are not a big problem, 2 generations of parts and they got it right with the green ones.
Without intake manifold tuning valves you really would be unhappy with the cars drivabilty and performance compared to what you have now
#78
#80