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Seems the #6 coil is bad. You'll want to change that. It should fix you right up.
The #6 coil is the one closest to the firewall, furthest from the front bumper.
Make sure you buy the ones Made In Japan, which SNG Barratt sells. You can also try the QYL coils which people have reported good experiences with for a lot less. Most all other aftermarket coils, and possibly even the ones the dealer will now sell you, will not last long. 6 months to a year at best. There are several threads, but that's the Readers Digest version.
Seems the #6 coil is bad. You'll want to change that. It should fix you right up.
The #6 coil is the one closest to the firewall, furthest from the front bumper.
Make sure you buy the ones Made In Japan, which SNG Barratt sells. You can also try the QYL coils which people have reported good experiences with for a lot less. Most all other aftermarket coils, and possibly even the ones the dealer will now sell you, will not last long. 6 months to a year at best. There are several threads, but that's the Readers Digest version.
Thanks so much for the reply. My boy got home with it late last night and so I finally got to run it this morning. It is indeed running rough like it's missing a cylinder. The coils and plugs in there presently are about 7 months old (I think you called that one). The coils are QYL from Amazon. I tried swapping out #6 (last cylinder before the firewall) with one we removed 7 months ago and it made no difference. So I removed all the coils and plugs in case there was something I could see. Most of the plugs were carbon black (pics attached. Sorry they're fussy. They are in order, with #6 being the right most with the whitest center). Plug 5 was the worst with a little carbon buildup. Most of the spark plug tubes had a little oil in them (teaspoon), while #2 had oil covering the plug entirely. I'll order new gaskets once this issue is fixed. I bought and installed a new set of plugs (I was already that far and they do stock them locally) and re installed the coils in reverse order (#1 was at #6 and #6 at #1) hoping I might see the error move position. Unfortunately the code was the same. I have another set of coils on order and due to arrive Friday. Same brand. But if it fixes the issue I'll look into ordering a better set. For now these will get here the fastest. If the new coils don't fix the issue, what would be my next best place to look?
It may not be the coils....you need to seal off the oil from entering the cylinder wells. That oil and moisture can easily short out the coils....
First thing I’d do is change the plugs, and then replace the spark plug gaskets. URO makes some and they are perfectly fine to use. Stay away from the other aftermarket brands like MTC. You can always buy OEM from the dealer if you want. While there, you may want to change the camcover gasket as well. You’ll need OEM, from the dealer, as I haven’t found an aftermarket source that works for the AJ16.
Anyways, once cleaned and dried, and I’m talking about the cylinders AND the coils themselves (remove rubber boot and shoot air down the hole and wipe down the metal cylinder part, reinstall and see if anything has gotten better. If not, then swap to the new coils you have on order.
Just to add to the great input you've already received from Vee, you really do need to get the threads in the spark plug holes cleaned up as best you can. Since the threads are the ground path for the spark plug through the cylinder head, head bolts, block and engine ground strap, oil baked onto the threads can add considerable resistance that can prevent the plug from firing properly. Obviously, replacing the cam cover and spark plug tube gaskets is the ultimate solution, but you also need to do what you can to reduce the oil on the threads of the plug holes.
I start by using a hand-operated vacuum pump with a catch jar and section of tubing attached to reach down into the plug wells and suction out as much liquid oil as possible. You can also use the spray head of a large spray bottle (e.g. a Windex glass cleaner bottle). Remove the spray head from the bottle, insert the long tube into the plug well, hold a cloth over the spray nozzle and squeeze the handle to spray the oil into the cloth. A third option is to twist paper towels into long "swabs" and twist them down into the plug well to soak up the oil.
I then use a little brake cleaner or other zero-residue solvent and a long-handled bottle brush with plastic or brass bristles to clean the threads in the plug hole. It's no problem if a small amount of solvent leaks down into the cylinder.
I follow up with a shop cloth and long flat-bladed screwdriver. Wrap one corner of the cloth into a ball around the tip of the screwdriver and insert it into the plug well. Twist the screwdriver to collect remaining solvent and oil. Work it as far into the threads as possible, taking care not to allow the screwdriver tip to poke out of the cloth and scratch the threads. Repeat with a fresh corner of the cloth until it comes away reasonably clean. Use compressed air if available to dry the plug well with a few quick bursts.
Before reinstalling an old plug, clean its threads with a small hand-held wire brush or a wire wheel, taking care not to damage the electrodes. Spray with electronic cleaner or brake cleaner and allow to dry naturally or with compressed air before reinstalling and tightening to the correct torque.
Thanks all for the great info. I'd never considered that the oil could cause a coil to short out. I will remove all the plugs and give everything a thorough cleaning. It'll take a few days as I work the weekends. I'll be back with an update after it's completed.
Hi all. Today I cleaned up the oil, re sealed the leaky valve cover, installed brand new spark plugs and also brand new coils. However the engine is still not smooth and the error codes continue (P0306 and P1314). Also, I can smell the fuel when it's running. Not sure if that's from a cylinder not firing or maybe it's just running very rich? How can I tell? Again, any assistance appreciated.
If if you’ve been unable to move it by moving the suspected coil, and the spark plug has been changed, and the gasket on that cylinder is holding tight, you may have a deeper issue.
That would lead me to suggest that you may have some corrosion on the ECU contacts or the wiring is failing you. After that, the prognosis gets worse.
If you can get that code to move to a different cylinder when swapping coils, or make it go away altogether with a new plug or seal, we could be back in business.
p0306 is what we’re focusing in on. Here’s a good thread:
If if you’ve been unable to move it by moving the suspected coil, and the spark plug has been changed, and the gasket on that cylinder is holding tight, you may have a deeper issue.
That would lead me to suggest that you may have some corrosion on the ECU contacts or the wiring is failing you. After that, the prognosis gets worse.
If you can get that code to move to a different cylinder when swapping coils, or make it go away altogether with a new plug or seal, we could be back in business.
p0306 is what we’re focusing in on. Here’s a good thread:
Thanks Vee. Tomorrow I will swap plugs and coils between 5 & 6 just to confirm again it stays on 6. I'll also try disconnecting the battery for 10 minutes, just because it's something I haven't tried yet. Is there a chart listing pin outs for the connectors to the ECM? So I can test the continuity to the coil? I've looked up the location of the ECM, but there was some disagreement as to the exact location. Either under the hood near the passenger side firewall or in the passenger compartment behind the foot board. I'm asking because I'm at work now and won't be home till tomorrow. Any verdicts?
Thank you Lady P. Those diagrams will be a great help. I am not near the car presently, but I hope to get to it soon. I want to be sure I understand correctly before I dig into it. So at each coil there should normally be (key on, but engine not started) 12 volts (ish) across the two wires (green/black if I remember correctly) and when the engine starts the black wire pulses to ground triggering the spark? Also, what would be the process to put in a replacement ECM should it come to that? I thought I read that any replacement ECM has to be matched to the car? I have seen some repair services offering to rehabilitate the ECM, but I don't know what those services normally charge. Has anybody done this?
The Black X notation is the location on the Black ECU connector . To double check the wire color see link below page 57 with wire color codes on page 16
You will not see 12 volts or B + between the 2 coil wires as the ECU has not provided the timed ground path unless engine running
you can get a ground path other then the valve cover as it's electricaly insulated from the engine block by design
The ECU's are the same across the world hardware wise but are different in the software
There is a ECU available in Kansas Kansas City that has the R - 493 TSB accomplished which has a different stet of data maps in the PROM's to match the upgraded EGR valve
To match the ECU to the present engine with the TPS set at a certain point would be to measure the donor car TPS sensor setting and adjusting your car TPS setting and they should match in theory
The spec on the TPS is 0.60 + or - 0.02 volts DC on the idle mechanical stop on the middle wire of the TPS connector or the Green / Yellow wire as it goes over the top of the fuel rail , you can nick the wire insulation
You can check with the engine not running , just key on as the ECU will power the connected TPS
The TPS sensor can be loosened up to adjust without taking the whole throttle body off but requires patients and a couple of beers
Another way to look at it is a trail and error method where you put the TPS on 0.60 volts and test drive . Then put on 0.59 . Then on 0.61 and soo on till you find the sweat spot
The ECU purchased may have a TPS sensor " null setting " of 0.61 or whatever so you'll have to find it
The TPS sensor has mounting hole of a certain size that don't offer much adjustment slack but can be drilled up a size to get more slack
It is may opinion the O2 sensors will relearn their new perimeters after a while of driving
Last edited by Lady Penelope; 03-03-2019 at 02:58 PM.
Thank you Lady P. I'll be going through the info you've posted over the next few days. This morning I swapped the plugs and coils for cylinder 3 and 6. There was no change other than it took about 20 minutes of run time before the errors popped up (P0306 and P1316).. The last time they popped up within 2 minutes. It's also pretty obvious that there is a misfire, as the engine wobbles a lot. In any case I've beaten the coil and plug thing to death and time to move on to the wiring and ECM as the cause. Unless, could this be a fuel injector issue?
I suppose it could be an injector issue, but I find that unlikely, as, I believe, there are codes for failing injectors. I don’t recall anyone posting seeing them, which is the cause for concern. It’s a little bit of work to free an injector. If you were able to swap injectors (do not swap it into the same place you moved the coil, move it to #4?) you could rule that possibility out.
If you start going down the wire route, I believe I have the specs for the pigtail you’re going to want to replace. I’m assuming you’ve sprayed electrical contact cleaner on the contacts?
A continuity test should provide proof that the wire is good, but might not reveal an intermittent short. ECU could prove to be faulty as well.
I suppose it could be an injector issue, but I find that unlikely, as, I believe, there are codes for failing injectors. I don’t recall anyone posting seeing them, which is the cause for concern. It’s a little bit of work to free an injector. If you were able to swap injectors (do not swap it into the same place you moved the coil, move it to #4?) you could rule that possibility out.
If you start going down the wire route, I believe I have the specs for the pigtail you’re going to want to replace. I’m assuming you’ve sprayed electrical contact cleaner on the contacts?
A continuity test should provide proof that the wire is good, but might not reveal an intermittent short. ECU could prove to be faulty as well.
Is there another connector at the firewall for the cable? Or is it a direct connection from ECM to the coils? If it's a faulty ECM, what's involved with swapping in a used one (provided I find a worthy replacement)? I read somewhere about having to reset the "immobilization". ??
There is no wire slice or connector in between the coil to the ECU connector as the ECU provides the ground path spark command
The O2 sensor return wires back to the ECU are the same uninterrupted wire
There have been reports of corrosion on the wire bundle getting into the wire conductors as it passes through high on the firewall with a grommet seal . This wire bundle contains 1 / 2 of your engine regulation wires
Vee , you still need that grommet seal as another X300 arrived in KC
There is a Innova 4400 coil tester machine in the back room of some but not all O'Reily Auto parts stores , call first .
The store personnel are not up to speed on this machine or it's operation so you may have to operate it yourself
Just let them know you are aware of the dangers of coil operation and have some heavy leather gloves to give them confidence
The adapter in the kit drawer is the lower adapter # as is a very generic connection or it could be the one around # 34 off the top of my head
Keep in mind the power switch is on the back of the machine
For what ever it's worth all of my 110 K mile original Lucas made in Japan coils passed
The Innova tester does not give you a number value but a pass / fail
There is a specification sheet on the Wells brand replacement sheet referred to as the Wells # C1079 off the top of my head with a figure of 35,000 volts which is higher then most
It is my opinion that this is not a true test at warmed up temperature were they fail , it may be the delay observed in the codes appearing
In the big picture of the coil operation there is 4 things to look at
Any one or all of these factors add up to a total degradation valve of a coil to the point it under performs causing observed problems
Quality of coils power source
Condition of coil
Coil plug tip
Return ground path and ECU switch quality , this switch quality would be hard to measure in the short time it accrues but you can ensure the ECU has good ground wires
Some have wrapped the barrel section of the coils with easily available Kapton tape to better insulate it from arcing to valve cover
The quality of power for all 6 coils is dependent on the pin 4 ( White / Pink wire ) on the Papa Indy 1 connector located behind the wiper fluid fill cap , this connector can get corroded from history
There are basket filters on the inlet side of the individual injectors that get clogged up , the filters can be popped out and replaced or maybe cleaned with a MEK chemical based solvent . I have seen a pic of a very gucked up fuel rail
Thank you again Lady P. I'm going to owe a lot of rounds at the pub when this gets fixed. Tonight my boy removed the ECM and took a pic of the numbers. I'll post that soon (I 'm at work). There was no corrosion. He plugged it back in and it still runs poorly. So much for re seating the cables. He noted that the cables did not come far down and were difficult to manuver. Is that pretty much it? Or can they be brought down further (coiled up somewhere)?
Unfortunately there isn’t a lot of slack down there.
The connector, at the coil, if you want a new one is a Sumitomo 6195-0003. You’ll need about 67” of wire if you wanted to rerun it, using the same path.
If that grommet on the X300 is the same as the one on the XJS, heck yeah, I’d love one!
Vee , I'll look at the new arrival in the land of many dreams or broken dreams
BobbyDing , there is not much slack on the ECU connectors and I found removing the ECU mounting helps
On the ECU sockets look for 2 tabs in each socket / squares that must pinch the ECU side pins / blades , sometimes one of the 2 tabs is loose or missing
The coil connector has a rubber seal in it that can swell from chemicals and possibly not let the pins make a good connection , You can remove the seals and give it a try
There are the 2 / 12 wire connectors next to each other that look alike located just behind the washer fluid cap that can be checked easily , These 2 connectors also carry several engine regulation wires one being a single wire for all 6 coils power
Finishing upper post overnight
Last edited by Lady Penelope; 03-04-2019 at 09:24 PM.
02-26-2019, 10:09 PM
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