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4.2L V8 w/ M112 (+8%) AJ34S 2003 S-Type R 82,XXXmiles
Misfire Cylinder 5, Cylinder 6
Catalyst damage - Bank 1, Bank 2
Swapped coils around, didn't change the cylinders misfiring
Replaced 8 plugs, 2 coils and the issue went away.
2 1/2 months later the issue has come back with the exact same codes.
Local 'any make, model' mechanic at the Chevrolet dealership says it's ECU - take it to the Jaguar dealership.
Passed compression test, and Jaguar dealership said its likely lower supercharger seal and essentially gave me a run-down of the 80,000 mile servicing it needed. I don't doubt their knowledge of the 5.0 V8, or any of the classic models but I thought it weird that a leak would only effect two cylinders and I had just done all of that routine maintenance myself 6 months ago when I downsized the SC pulley. I decided to go to you folks and a local mechanic before forking out 85% of the cost of an AVos/KB twin-screw kit for the local dealership to start guessing.
I have it scheduled for a smoke test to look for vacuum leaks at a friends garage - but assuming I pass the vacuum test like I did the compression test where do I start after that? Is there anything I'm leaving off and what are everyone's opinions on what I do first and if I've left off anything?
Battery check - only 2 years old but haven't tested since pulley install
8 Plugs, 8 Coils
Valve cover/Cam cover/spark plug well gaskets
Catalytic Converters - on the to-do list anyway
02 Sensors
Crankshaft position sensor
Do I even have plastic camshaft tensioners in the 2003 4.2? Maybe those.
?????
What else?
Will get LT and ST fuel trims logged when I get the car back from the dealership out of town.
Last edited by Alex Shumpert; 09-08-2017 at 02:30 PM.
did you buy cheep coils ? there is a lot written around the place about dud aftermarket coils .maybe shift them around again .and check your fuel trims as jagv8 mentioned . it will tell you if you need to smoke test it or not . there is plenty of posts here and on youtube on how to do that .
if your cats are clogged , its almost aways accompanied loud pinking sound under boost conditions .
Your P/B vacuum connection on the back of the SC intake elbow is most likely leaking and causing at least part of your problems.
Has this been changed and are you aware of it?
Pretty much guaranteed to happen because of the way it's made. A very cheap repair but as you know removing the SC is not easy. Also be sure and replace the dreaded under SC coolant hose.
We have several very in depth threads on the forum if you can't find what you are looking for.
Yes ignore the ECM comment. He is clueless and just fishing around. This forum has the answer we just need to find it!
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Getting ready to go pick her up from the jag dealership in a few and figured I'd help clear the basic questions out.
Yes, I have swapped the new coil packs around after this happened the second time (just recently) and JUST like the first time the coil packs don't APPEAR to be the cause - but replacing them seemed to solve my problem the first time so I may as well purchase dealer approved coils and plugs now to be sure.
P/B vacuum connection?
I want to say I made sure ALL of those were snug when I reassembled the damn thing the third time in search of a leak that ended up being the EGR valve. Will double-check and triple-check that too. I assume it would be easy enough to see during a smoke test?
For some reason I decided to replace the SC valley coolant hose when swapping pulleys. Got to the old one and found out it had already been replaced. Better safe than sorry, I guess. Replaced every gasket last time, and will likely have to do it again? I'm sure that if I have to remove the blower I'm going to be cleaning the injectors and charge coolers this time as well. But that's a good bit of work even having done it three times now.
Last edited by Alex Shumpert; 09-09-2017 at 12:07 PM.
Well the problem is the P/B vacuum connection has a rubber internal O-ring. There is no tightening of the connection.
Take a look here as I fought with this on my 2005 STR. This thread has a number of other links so it's a lot of information and I made the post in an attempt to cover all the bases.
When I got her home the fuel trims suggested an air-leak. Throttle body cleaner indicated it was at the back of the engine when my FT's spiked to -25ST from a +11-+13LT at idle.
Removed everything from air-box to lower-intake plenum and rinsed everything aside from the throttle body with copious amounts of throttle body cleaner. My inter-coolers were nasty.
Sent injectors off to the local shop for testing
Ordered denso plugs, oxygen sensors and A/F sensors, along with an aftermarket water pump, and duralast knock sensors, crankshaft position sensor, camshaft position sensors. Removed the PB vacuum fitting as well and installed the brass compression fitting to rule that out as the culprit. Also decided to do the cam cover/plug well gaskets while it was in the garage and an install of the methanol injection system I had laying around.
Possible catch-can install as well - but the one I ordered via eBay ended up being a piece of junk that I wouldn't even put on the Neon down the street.
Parts store is running a good deal on Duralast coils - has anyone had good/bad experiences with Duralast/Wells coils? I can only seem to find the coil boot for the original Denso's. I still have them laying around, but have no experience changing coil boots and they seem to be stuck on pretty tight.
edit: Import Direct Water pump came with a felt/cardboard gasket. JTIS says the water pump should have a rubber O-ring and the forums seem to tell me that the gasket that works without an o-ring is a metal crush gasket.
What gives?
Last edited by Alex Shumpert; 09-20-2017 at 05:01 PM.
Just got off the phone with my INDIE mech - he explained what a coil control driver is and that #5 (and likely #6) may be going out after fighting to spark old coils under increased boost in oily plug wells.
Anyone have experience with this problem? Something tells me that I won't be able to find a cheap FORD fix for this.
Engine re-assembled and both a smoke test and three cans of TB cleaner have confirmed that there is now NO vacuum leak to be found. Engine still has at least one dead cylinder that is easily felt during idle.
Still really confused as to WHY bank one is acting so ridiculous.
I've swapped both A/F sensors around to see if they happened to be defective, and I still get the same response from fuel trims as if Bank 1 is getting unmetered air. MIL indicates codes P0171, P0301, P1316
Battery voltage from the test mode lower than expected - at 12.1v. Replacing it tomorrow.
Assuming the battery isn't my problem either, what next?
What could cause my bank 1 fuel trims to be reading like this? I just had my injectors tested and cleaned up. New plugs and coils in all 8 cylinders. P/B booster has been fitted with a brass compression fitting, anaerobic gasket, and a little bit o' heat shrink just because.
Next culprit is valve springs??
Last edited by Alex Shumpert; 10-02-2017 at 06:43 PM.
by A/F sensors i think you mean o2 sensors ?
a p0301 points towards a bad coil, injector or the wiring for one or the other leading to cylender no#1 so id be starting there .
there very well could be a exhaust flange leak also . just up stream of the o2 sensors .
causing your funky trims .
it has happened to me and i've seen other people come across this too and document it . so also well worth a look as a last resort . i think definitely before you open the engine .
a compression test will show if any valves are bad anyway .
but a leaking flange wont throw a miss fire code .so i dont think its that.
so start by listening to the injectors with a stethoscope to make sure they are pulsing .
if so then test the coil wires leading to cyl#1 , my guess is a broken wire .
have you physically seen the no#1 coil making sparks ?
you can remove the coil with it plugged in , then fit a spark plug in the coil and earth a spark to ground .
Car was left outside last Thursday and Friday. We received quite the downpour both nights prior and the mechanic says the misfire hasn't returned since getting a good soaking on Wednesday. When it returns - I trust he'll find the short rather quickly.
The fuel trims on bank one are still supposedly "wonky", but I haven't personally seen them since the misfire decided to magically disappear.
This points towards either leaking passenger side PCV valve or an exhaust leak for the fuel trims and a short in the wiring for the misfires?
edit: and yes, I meant the upstream 02/wideband sensors.
Last edited by Alex Shumpert; 10-09-2017 at 10:56 AM.
09-08-2017, 02:16 PM
Misfire Cyl 5 & 6 - 2003 STR
Better safe than sorry, I guess. Replaced every gasket last time, and will likely have to do it again? I'm sure that if I have to remove the blower I'm going to be cleaning the injectors and charge coolers this time as well. But that's a good bit of work even having done it three times now.
