hi after a six month rebuild on my 4.2 v8
and getting a new code B0300 network management expulsion that has been doing my head in
took car to jaguar dealership today

Some have said it was my scanner

Well dam jaguar nz got the exact same code as i did
BO300

this is where I get confused
$800.00 nzd later we think might have found the problem
3 coils stop working under load

yet when coils were tested by auto electrical shop they said they were fine

so this is what I have found out 8 coils working fine at idle and crusin 3 coils go to sleep under load but come back on once lift foot off Accelerator

no misfire codes no Restricted performance on Instrument cluster

jaguar nz also tested the ecu and wiring all working perfectly

Yes they were brand new coils from sng Barratt
this has been a 11 k engine rebuild
I honestly didn't see this coming

Thanking you
Darrol

 

For what you describe, should be a P code. Also, there's no B0300.

The tool is almost certainly wrong. I'd use a better one e.g. IDS/SDD.

 

Even WDS sometimes gets the DTC prefix wrong. (usually at the bottom of the list stating NO DEFINITION)

Just go with P0300 and solve the problem.
A random misfire does NOT always mean IGNITION COIL.

 

when I took my car to jaguar new Zealand yesterday B0300 NETWORK MANAGEMENT EXPULSION was the only fault they brought up as well

 

Can you please elaborate how this was determined?

Years ago, I had a big automotive scope that showed secondary ignition patterns. You did a snap accel and could see if any cylinders displayed an unusual pattern under this brief load. This was for regular systems of the day, with a single coil and distributor. You could really tell a lot about conditions inside the cylinder, such as a fouled plug or even possible low compression. However, I'm not aware of any means to run a similar test with a coil-on-plug system. So please provide more details about how this diagnosis was reached.

You mentioned three coils not working properly. Normally I'd say just replace them and move on. No guarantee any parts are good just because they're new. (Forum members, feel free to sing along on the chorus.) But not knowing how the coil problem was determined, I'd really like to know more details before spending your money. At the very minimum, you could swap the suspect coils with other known-good positions to make sure the faults follow.

And I bring this up again in the most courteous manner possible, but what symptoms are you experiencing besides the mystery B0300 code? Any rough running? Hesitation? Check engine light? Those mind-reading pills I got on eBay seem to have been a scam. Might be easier for everybody if you just told us instead of making us guess.

 

Hi this is what I know
as I have only really found out what they did today
I still have not got my car back yet

Took car for its first run checked for fault codes before leaving no codes car went great no issues at all got home checked for codes had B0300

Cleared codes another run no issues no Restricted performance light fault B0300 back a gain

started to really bug me

so we Took car to jaguar dealership for the day
And along with a friend who used to work there but now dose computer engine Diagnostics

he had made a program to read what a coil was doing
by using a piggyback connection going to his laptop

Car was put on to a rolling road and testing was done
I was told 3 coils would stop working under load for around 5 to 15 seconds and B0300 code kept coming back
but for some reason was not given a p0 fault

They then replaced the 3 suspect coils with my old ones
re did the testing no B0300 fault
then put the 3 new ones back in retested had B0300 fault back

They also did comparison test all cylinders at 185 psi
then tested with engine running compression was 300 psi at 3000rpm

have a lot going on at the moment as our daughter has lost everything including her home when cyclone Gabriel hit new Zealand last Tuesday

When I find out more I will post it
Thanks
Darrol

 

This member of the chorus sure thinks that you got three bad coils right out of the box, What brand were they?

Sorry to hear about your daughter's misfortune!

 

hi thanks

I purchased 8 coils part number AJ810445
I purchased these from sng Barratt in the uk
brand Denso /jaguar
These were what barratts recommended
these cost me with exchange rate $170.00 nzd each plus shipping
so all up coils cost me $1560.00 new Zealand dollars

 

Interesting. Reading between the lines, this is not an official Jaguar test procedure, but rather it's something your friend devised? Is that correct? Sounds quite ingenious, but I wonder if it can give false indications of a problem. In other words, perhaps it is too sensitive under certain conditions, or electrical interference from other sources can throw it off.

I'm very curious how this program works. I don't know of any means to measure the coil output (high voltage), unless you had something physically connected between the coil and spark plug. So once more reading between the lines, I'm guessing this program somehow monitors the input (low voltage) side of the coils. The program then interprets the current flow through the input side to deduce what the coil output must be in a perfect world.

One thing I have learned the hard way as a mechanic: When your test results don't make sense, you need to revisit the test procedure. For example, I've had a meter fail in such a way that it would not indicate above a certain level. Below that point, all looked good and it behaved as expected. But when the meter should have shown a higher value, it stayed low. Talk about a head scratcher. Lots of possibilities like that.

I've also had LOTS of instances when electrical interference (from other circuits) would skew test results, especially when measuring very low-powered signals. This could easily be what you're seeing.

Another thing that makes me suspicious is if you lost three coils simultaneously, you should notice a big drop in power. You may not notice one cylinder, but I think three at once would be hard to miss. You'd also have a power imbalance and get P030x codes for those specific cylinders, but I'm not sure how long must elapse before getting individual misfire codes. The brief time may not be enough to register.



So this kinda sounds like you've successfully isolated the problem to these three suspect coils. With the three old coils reinstalled, all is good. Is that correct? No performance issues or the mystery B0300 code, right? If so, are you mostly just trying to understand why the three suspect coils were causing the B0300 code? You may never have a good answer on that one. You might never know why, just that it is. You may have to settle for that.