Fuel starvation and massive detonation - RESOLVED
#101
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Yes the sensor may be wrong, although that does seem less likely now given that changing to new pumps resolved the pressure dropping off. I have since been informed that the other X350 XJR that got new pumps was also doing the same thing. The audible difference between the old & new pumps is also indicative of "better" I am 99% sure there are no fueling problems with this car now (1% on clogged injectors)
![Fuel starvation and massive detonation - RESOLVED-maftest8.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108117d1480975128t-fuel-starvation-massive-detonation-resolved-maftest8.jpg)
I doubt that, the car is making less power than it did 12 months ago (or > 2 years ago) with the same pulley & intake, there were no apparent issues back then. Other engines with more extensive mods have not reached that limit. And they made good power, mine doesn't at the moment...
The injectors from the 4.2 have enough flow for >500hp at stock pressure, the only way they could be maxed out is if they were blocked up, which is one reason why I was thinking of the carbon cleaning. Avos was running the stock 4.2 injectors at ~600hp
But of course, it is supposed to track air flow so it is dependent on the MAF reporting correctly. But, if it ever hits 100 percent, you are hosed without using a rising rate pressure regulator
to compensate. At 100 percent, you just can't get any more fuel no matter what the ECM commands.
to compensate. At 100 percent, you just can't get any more fuel no matter what the ECM commands.
There are a number of pinpoint tests that are in the manual for the X308, and are probably in SDD for the X350. These are
electrical tests.
There are at least 5 pinpoint tests for MAF performance
that you can look at. Requires a DVM.
The whole range of the sensor pinpoint tests is under
powertrain/electronic engine controls/pinpoint tests
electrical tests.
There are at least 5 pinpoint tests for MAF performance
that you can look at. Requires a DVM.
The whole range of the sensor pinpoint tests is under
powertrain/electronic engine controls/pinpoint tests
The flap was removed a long time ago.
Have not been specifically monitoring. BUT in the past I did have overheat issues (stuck thermostat) and there was no pinging then, even at well over 110ºC
As you can tell, I'm looking to the MAF and fuel injector flow as the culprits with the MAF being number one.
You could try digesting the principles in:
AutoSpeed - Airflow Meter Bypass, Part 1
AutoSpeed - The Digital Fuel Adjuster, Part 1
with the goal of at least temporarily inserting a electrical
adjustment to the MAF output at WOT for testing purposes.
If pushing the MAF output to trick the ECU into seeing more
air at WOT makes the pinging disappear, that would be confirmation
of what has to be done.
For testing purposes it would be enough to use a single resistor
with leads running to the cabin through the window terminating
in a switch you can throw at WOT to cause the MAF circuit
to report more air.
That's an AU based site BTW.
++
You could try digesting the principles in:
AutoSpeed - Airflow Meter Bypass, Part 1
AutoSpeed - The Digital Fuel Adjuster, Part 1
with the goal of at least temporarily inserting a electrical
adjustment to the MAF output at WOT for testing purposes.
If pushing the MAF output to trick the ECU into seeing more
air at WOT makes the pinging disappear, that would be confirmation
of what has to be done.
For testing purposes it would be enough to use a single resistor
with leads running to the cabin through the window terminating
in a switch you can throw at WOT to cause the MAF circuit
to report more air.
That's an AU based site BTW.
++
Just to throw another one out there, it's been suggested that a failing Coil-On-Plug could cause this...without codes for misfires or coil-related problems it'd be a case of replacing a bank or the lot. Any ideas on how to isolate a bad COP without knowing which one is bad (or there might even be multiple)
WOT flap removed from airbox, K&N filter, SS intake tube in place of the stock plastic one with bellows, chambers, restrictions, etc. Same as it's been for the last couple of years. No changes.
#102
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#103
#104
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The problem with the images not showing may be that they are
not publicly visible to someone without the user credentials. They
would be visiible to you since you have the credentials cached on
your own machine.
Turning to the one image I can see ...
I would log the following:
rpm
air mass
throttle position
absolute manifold pressure
ignition timing
fuel injector duty cycle
closed loop status
Having those datum in a synchronised timeline would be useful
in seeing any anomalies in the ECM view of the world as well
as identifying where you are at particular points of the test.
not publicly visible to someone without the user credentials. They
would be visiible to you since you have the credentials cached on
your own machine.
Turning to the one image I can see ...
I would log the following:
rpm
air mass
throttle position
absolute manifold pressure
ignition timing
fuel injector duty cycle
closed loop status
Having those datum in a synchronised timeline would be useful
in seeing any anomalies in the ECM view of the world as well
as identifying where you are at particular points of the test.
#105
#106
#107
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Ah OK then.
Well I just went nuts & ordered 8x Airtex coils, 8x Denso plugs, 2x Denso O2 sensors and an Spectra MAF
Rock Auto has a good selection, $930 delivered that's $650 cheaper all up than buying from the UK (Aussie dollars).
How do I justify this?
- The plugs in the car don't look all that great anyhow...
- The MAF is the original unit at 11 years old & 174'000kms
- The coils are original at 11 years old & 174'000kms
- The O2 sensors are original at 11 years old & 174'000kms
Will know more in a week or two...
Well I just went nuts & ordered 8x Airtex coils, 8x Denso plugs, 2x Denso O2 sensors and an Spectra MAF
Rock Auto has a good selection, $930 delivered that's $650 cheaper all up than buying from the UK (Aussie dollars).
How do I justify this?
- The plugs in the car don't look all that great anyhow...
- The MAF is the original unit at 11 years old & 174'000kms
- The coils are original at 11 years old & 174'000kms
- The O2 sensors are original at 11 years old & 174'000kms
Will know more in a week or two...
#108
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#109
#110
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Just ordered a new fuel pressure sensor as well, for $85 delivered it's crazy not to change it...
Because a little bird told me that it can happen that the pressure sensors start to fail, and they read high, to which the ECU reduces fuel flow, which leads to a lean-out...
So i'm told...
Because a little bird told me that it can happen that the pressure sensors start to fail, and they read high, to which the ECU reduces fuel flow, which leads to a lean-out...
So i'm told...
The ECU would reduce fuel injector duty cycle to compensate for higher than expected fuel pressure.
The other way to compensate would be to reduce duty cycle at the pump, but that would be
a coarser and slower adjustment.
The two mechanisms are probably used in concert.
Your reported 70 psi does sound a tad high. A mechanical fuel pressure gauge would have proven it
one way or the other.
I think you just like shopping
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#111
#113
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Plugs, coils and O2 sensors arrived today, pulled the old plugs;
![Fuel starvation and massive detonation - RESOLVED-img_0629.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108502d1480975258t-fuel-starvation-massive-detonation-resolved-img_0629.jpg)
![Fuel starvation and massive detonation - RESOLVED-img_0631.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108504d1480975258t-fuel-starvation-massive-detonation-resolved-img_0631.jpg)
![Fuel starvation and massive detonation - RESOLVED-img_0632.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108505d1480975258t-fuel-starvation-massive-detonation-resolved-img_0632.jpg)
Oops I forgot to take a pic of one of them...it was also sooty, not much brown unlike #1 & #8
The 3rd pic is #1 which is the same plug as previous pics, you can see the difference in colour and deposits compared to before. I guess that's the detonation at work...
4th pic is #6 (left) #8 (right) surprises me to see such a difference in the cylinders.
Haven't been out for a drive with the new plugs/coils, waiting on the fuel pressure sensor to arrive since it'll be easier to install with the scuttle & cabin filter removed.
Depending on work I might put in the new O2 sensors this week.
The MAF that I bought is a dud. Aftermarket item from Spectra Premium via Rock Auto. I didn't even take it out of the bag, somehow the design is completely different, there is no hole in the sensor body for air to pass through. Very strange, so i've sent that back.
In the meantime Avos pointed out that the MAF signal appears fairly normal based on an old dyno sheet of this car, between ~5000-5800rpm the engine only makes 30rhwp more, and the MAF measurement was an increase of about 30g/s over that range, which correlates about right.
So, waiting, waiting, waiting for my fuel pressure sensor...
![Fuel starvation and massive detonation - RESOLVED-img_0628.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108501d1480975258t-fuel-starvation-massive-detonation-resolved-img_0628.jpg)
![Fuel starvation and massive detonation - RESOLVED-img_0629.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108502d1480975258t-fuel-starvation-massive-detonation-resolved-img_0629.jpg)
![Fuel starvation and massive detonation - RESOLVED-img_0630.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108503d1480975258t-fuel-starvation-massive-detonation-resolved-img_0630.jpg)
![Fuel starvation and massive detonation - RESOLVED-img_0631.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108504d1480975258t-fuel-starvation-massive-detonation-resolved-img_0631.jpg)
![Fuel starvation and massive detonation - RESOLVED-img_0632.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108505d1480975258t-fuel-starvation-massive-detonation-resolved-img_0632.jpg)
Oops I forgot to take a pic of one of them...it was also sooty, not much brown unlike #1 & #8
The 3rd pic is #1 which is the same plug as previous pics, you can see the difference in colour and deposits compared to before. I guess that's the detonation at work...
4th pic is #6 (left) #8 (right) surprises me to see such a difference in the cylinders.
Haven't been out for a drive with the new plugs/coils, waiting on the fuel pressure sensor to arrive since it'll be easier to install with the scuttle & cabin filter removed.
Depending on work I might put in the new O2 sensors this week.
The MAF that I bought is a dud. Aftermarket item from Spectra Premium via Rock Auto. I didn't even take it out of the bag, somehow the design is completely different, there is no hole in the sensor body for air to pass through. Very strange, so i've sent that back.
In the meantime Avos pointed out that the MAF signal appears fairly normal based on an old dyno sheet of this car, between ~5000-5800rpm the engine only makes 30rhwp more, and the MAF measurement was an increase of about 30g/s over that range, which correlates about right.
So, waiting, waiting, waiting for my fuel pressure sensor...
#114
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Are you sure there's detonation?
#115
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For me it looks like there's no detionation, but it is possible that there's pre-ignition of the mixture from a carbon deposits in the cylinder(s).
If it was a one of my customers cars - i'd take a good look into the cylinders with a scope.
#116
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As far as I understood the misfires (that is how I read it for now) occurred at wot and high rpm, so the plugs have only been very briefly exposed to that condition.
The mixture should be measured at wot to know if it is good or bad, and ideally also an external gas analyser test (in neutral about 2500 rpm) so you know that the ECU is able to keep lambda perfect. With that you will have ruled out already many potential issues that can cause misfires.
Next would be the cops, malfunctioning ones can show their ugly head only under boost causing misfires.
If that all shows to be fine, and the condition stays bad at wots, it may also be clogged catalysts.
The mixture should be measured at wot to know if it is good or bad, and ideally also an external gas analyser test (in neutral about 2500 rpm) so you know that the ECU is able to keep lambda perfect. With that you will have ruled out already many potential issues that can cause misfires.
Next would be the cops, malfunctioning ones can show their ugly head only under boost causing misfires.
If that all shows to be fine, and the condition stays bad at wots, it may also be clogged catalysts.
#117
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What surprised me was the colour change and clumpy deposits on plug #1 compared to a few weeks ago.
The car has only done less than 30km since this all started, and most of those have been on the motorway with some WOT runs. So the colour change kind of makes sense. But the variation in colour between the cylinders is what has me wondering...
I've had a couple of cars in the past that pinged, so i'm pretty sure I know the sound. But it could also be pre-ignition like MoscowLeaper says.
Yep. For me the plugs looks like the AFR is pretty rich, no evidences of the detonation can be visible on the plugs.
For me it looks like there's no detionation, but it is possible that there's pre-ignition of the mixture from a carbon deposits in the cylinder(s).
If it was a one of my customers cars - i'd take a good look into the cylinders with a scope.
For me it looks like there's no detionation, but it is possible that there's pre-ignition of the mixture from a carbon deposits in the cylinder(s).
If it was a one of my customers cars - i'd take a good look into the cylinders with a scope.
I looked into the carbon-cleaning, there is no-one local to me with the equipment that I could find. The DIY options are Seafoam or the Subaru Upper Engine Cleaner but some people have said that using this on a high-mileage engine that has not been cleaned before could choke up the catalysts because of so much crap being released from the cylinders.
As far as I understood the misfires (that is how I read it for now) occurred at wot and high rpm, so the plugs have only been very briefly exposed to that condition.
The mixture should be measured at wot to know if it is good or bad, and ideally also an external gas analyser test (in neutral about 2500 rpm) so you know that the ECU is able to keep lambda perfect. With that you will have ruled out already many potential issues that can cause misfires.
Next would be the cops, malfunctioning ones can show their ugly head only under boost causing misfires.
If that all shows to be fine, and the condition stays bad at wots, it may also be clogged catalysts.
The mixture should be measured at wot to know if it is good or bad, and ideally also an external gas analyser test (in neutral about 2500 rpm) so you know that the ECU is able to keep lambda perfect. With that you will have ruled out already many potential issues that can cause misfires.
Next would be the cops, malfunctioning ones can show their ugly head only under boost causing misfires.
If that all shows to be fine, and the condition stays bad at wots, it may also be clogged catalysts.
New O2 sensors to (hopefully) reduce the richness.
New fuel pressure sensor will go in to rule that issue out. Looks like it has not been shipped from the UK yet so I will probably have to buy one local at twice the price...
Regarding the catalysts, they are the originals so 108k miles on them, were on my list of things to do, are now at the top of the list.
Once the O2 sensors and FPS have been changed then I will make some more road tests, and head to the dyno to do runs with the wideband in the tailpipe, and more logging with the SDD. Hopefully those runs will be with a good running engine, but we'll find out sooner or later.
#119
#120
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OK so I put in the new O2 sensors, and couldn't help myself, had to go for a drive.
So this is with new plugs, coils and O2 sensors. Still waiting on the fuel pressure sensor to arrive, probably another week...
The scuttle removed, no wipers, no cabin filter.
![Fuel starvation and massive detonation - RESOLVED-img_0655.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108604d1480975258t-fuel-starvation-massive-detonation-resolved-img_0655.jpg)
So it sounds awesome inside the cabin, except for the pinging...![Frown](https://www.jaguarforums.com/forum/images/smilies/frown.gif)
Here's a recording, it's an .m4a file off an iphone, but I had to zip it in order to upload to the forum.
New Recording 2.zip
So this is with new plugs, coils and O2 sensors. Still waiting on the fuel pressure sensor to arrive, probably another week...
The scuttle removed, no wipers, no cabin filter.
![Fuel starvation and massive detonation - RESOLVED-img_0655.jpg](https://www.jaguarforums.com/forum/attachments/xj-xj6-xj8-xjr-x350-x358-28/108604d1480975258t-fuel-starvation-massive-detonation-resolved-img_0655.jpg)
So it sounds awesome inside the cabin, except for the pinging...
![Frown](https://www.jaguarforums.com/forum/images/smilies/frown.gif)
Here's a recording, it's an .m4a file off an iphone, but I had to zip it in order to upload to the forum.
New Recording 2.zip