That was your lungs.

Can it flow XX gpm @ zz psi?

Are you willing to risk bridging the fuel line with some hose for testing?

Or tee in a second filter in parallel?

The simplest of all would be to replace the Mahle with the genuine
Jaguar unit. Certainly worth a try when compared to the cost
and difficulty of fuel pump replacement.

 

Ok.

Too used to interpreting direct readings as used in the former incarnation of the engine.

 

Which code?

Agreed but it in these sort of cases, would you replace only one? If one is going the other can't be too far behind. Some things you just have to replace in pairs...

My thoughts on (the assumption of) why the pumps aren't delivering what they should, possibly;

Motor/s are tired
Clogged up internal filters
Internal check/releif valve leaking
Impellor worn/eroded

If they are being spun faster than they normally would be to deliver the demanded flow rate (and this is an assumption based on the pressure being higher than 55psi) then something is wrong with them.

These pumps should be capable of delivering for well over 500hp, i'm nowhere near that...

The pumps and internals aren't serviceable, so replacement is the fix for any internal issue...

AND I have heard of a few "high mileage" XJR's and STR's that have needed new pumps, not to mention Charlies fun with his XKR.

Is there a code for "poor fuel pump performance" ? I don't think so...

So I can just chuck parts at it & hope...

New MAF, new Fuel Pressure sensor, new IAT2 sensor, what else?

True, but I have flow through the intercooler circuit, and no code related to intercooler problems e.g. P0096, P0097, P0098, P1474

The upstream O2 sensors are wideband https://www.jaguarforums.com/forum/x...5/#post1066841 and to be honest were on my list of "things that will need doing" I was going to change them when I had new cats installed, but the money for that went into getting the diff rebuilt, again...

What will monitoring the wideband tell me, if it shows going lean at the point of hesitation/detonation, it just confirms that there is a fuel delivery issue. If it doesn't then I need new upstream sensors, but again i've got no codes for that & as you confirm the fueling at WOT is based on the fuel map.

Seems plausible. But what's more likely, wiring degradation (no moving parts) or pump degradation (lots of moving parts)

The car is 10 years old and done 108'000mi, can we honestly expect the pumps to be performing at their best at this stage? I doubt it...especially since there have been reports of other vehicles needing replacement pumps...

Yeah but I replaced the Mahle filter with a genuine Jag one yesterday, drained the tank, put in new fuel, and it's still doing it...

 

Just wanted to say, thanks everyone for your input.

Tomorrow i'm off on a 3 week business trip. So the XJR is parked up & nothing more will be done for at least a month.

 

P0171, P0174, P0191, P0300 et al

List incorrect fuel pump output as possible conditions.

 

Heck no. The last thing I want on these type of anomaly problems is for you to throw parts at it.

It was more a matter of giving you ideas for parts to TEST to see if they might be the root cause. IIRC, there are pinpoint tests in the Workshop Manual for each of those components as well as the DataLogger in IDS/SDD to see what signals the ECU thinks it's getting.


BTW, other than the WOT hesitation and detonation, do you have any other indications of lean running? Your plugs look like they've been running rich.

 

But I don't have any of those...

Testing involves driving at WOT and if it keeps pinging then I'm afraid damage will occur, if it hasn't already...

Nope. No indication of lean running at low revs or during normal driving.

Well, not exactly.

After it first happened I was sure that the car was feeling sluggish at low revs & part throttle, did not feel as responsive as it usually was.

This car used to shove you in the back with 1/3 throttle from a standing start. Half throttle while cruising would be "oh wow", it wasn't like that anymore.

But yesterday after changing the fuel filter & putting in new 98 it felt like that again at low revs. But still pinging/hesitating up top.

Could just be the placebo effect...

 

You should be able to test each of those components without running at WOT. I haven't looked at the pinpoint tests, but they usually are pretty good.

I agree that until you know what's causing this, you should avoid WOT. No sense risking blowing a gasket or damage.


The lack of overall lean running, and the condition of your plugs, is why I keep coming back to something like a dodgy MAF, FRP sensor or vacuum leak.


EDIT - That's what I'm saying, if your pumps weren't working correctly, you should have one of those, but you don't.

 

If it keeps pinging could be the knock sensor seeing you have already put High octane fuel in it

Do these engines have variable valve timing could also be that sensor
As for Mahle fuel filter nothing wrong with that brand I prefer Mann Hummel but I also use Mahle as well

I don't think its the pumps!

I know this may sound crazy check you harmonic balancer have a good look

On my XJR6 it had come loose and the idiot at the dealer just re-tightened it

In the meantime when it came loose it bent the key and damaged the key-way on the balancer took 6 years and thousands of dollars to figure out why it always had a hesitation on take-of only found out when I replaced the water pump thought I would do the weeping crank seal at the same time hey presto

Just an idea

Its going to be a hard couple weeks away on business knowing the old girl has a problem

 

Well I figured i'd get an expensive fix out of the way, so I put in new pumps.

It's still pinging...

 

sigh ... i opened this thread after the pump removal tool thread earlier today
expecting tales of joy.

As you know, pinging is lack of fuel or too much advance.

You have SDD, have you done any data logging while out on a drive?

The particular items of interest would be:

- STFT, are the injectors going crazy trying to add fuel
- injector duty cycle
- O2 sensors, are they failing to keep fueling at the desired A/F ratio due to failure
- ignition advance, unlikely but might as well know

At the same time, a fuel pressure gauge taped to the outside of the windscreen
to monitor fp.

BTW, at WOT none of the closed loop trimming mechanisms are involved.
The ECM jumps straight to static tables that determine fueling and timing strategy.

++

 

Bummer.

It appears you have a situation where under certain conditions it is running lean, but not because of a lack of ability to deliver fuel, but because the ECM is telling the system to limit fuel delivery.

So I would think you need to concentrate on the things that would give false readings under those conditions -- MAF, O2 sensors, FRP sensor, etc.


Separately, I didn't know you were going ahead with replacing the pumps and was about to post to this thread that I mentioned your issue to a mechanic well versed in pwm fuel pumps used in Fords so it might translate to our cars. He said that if he suspects a weak or failing pump he measures the current draw of the pump, and if it draws more than 10amps that's when he'll look at replacement.

Sorry I didn't get to posting that sooner.

 

It also been suggested that carbon build-up could also cause pinging.
Given the age/mileage i'm thinking that it might be worth looking into a carbon clean. Can't find anyone local with the equipment though...

I'm also wondering if the engine oil might have something to do with it.
Changed the oil at the end of December, Penrite HPR5 5W40 full synthetic Penrite Oil - A Better Class Of Oil only reason I mention this is that it's one thing that changed on the car in the last few months, and "Auto-ignition of engine oil droplets" is a possible cause?

No I haven't logged these, because as you say ==>>

Yep, so i'm wondering what could be causing open loop fueling issues. It's based on rpm, throttle position, upstream wideband O2, knock sensors and mass air flow, and the fuel tables. One of these is not right somehow.

OK so it actually shouldn't be too hard to get a gauge on the line. It was staring me in the face the whole time. I was looking for the schrader valve which threw me off.



The hardline changes to a soft plastic line with a push-lock connector, you can see it in the left of the picture. The schrader valve isn't on that line. There is a 2nd line which looks like a return of some kind, I guess for the emissions. It's low pressure by the looks (plastic clamp) compared to the molded high pressure line on the left.



The high pressure line disappears into a black hole behind all those connectors, but I imagine it connects to the fuel rail back there. Funny because the JEPC shows the incoming fuel line goes on the rail below the pressure sensor, and outwards, not inwards. I dunno...





The pressure sensor is at the back of the engine on the left side looking forwards (not the right front like the XKR, or earlier XJR) and it does have a manifold reference tube. If it's meant to measure the differential pressure between the fuel rail and the manifold e.g. 15psi boost, 70psi fuel pressure = 55psi as per the books then getting 70psi shown on the SDD wouldn't be right? Maybe the manifold line is blocked/crushed? Maybe the sensor is duff?



The schrader valve is on the opposite side, on the other fuel rail (the little blue plastic cap) and you can see the fuel temperature sensor on that rail (grey connector)

If I was going to put in a gauge it would be on the incoming hard line, the scrader valve is virtually inaccessable....

But yeah, i'm wondering about the fuel pressure measurements.

Should be displayed as 55psi, not higher, right?

And it occured to me that the drop that I saw could be because manifold boost is dropping off in the high revs? (overdriven Eaton, loses boost in the top end?)

I think I need a better understanding of how the pressure sensor works. If it's meant to be measuring 55psi and it's not, that's something to look into further...

 

Yep, so i'm thinking;

O2 sensors, were on my to-do list anyhow. 34by151 here in Sydney has the same year XJR with similar miles. He replaced his O2 sensors. I do think that age/mileage means they won't be at their best. My plan was to replace the cats and do the O2 sensors at the same time. Might also have something to do with the car running rich, I understand that as they age they read lower AFR numbers, since it's safer for the car to go rich as they wear/fail than lean.

MAF, can't rule it out. Does the output drop off a cliff in the top end? Not sure how to test that...

Fuel Pressure Sensor. It's unclear to me if it's really reading correctly. Could also be that the sensor is ok but the manifold boost line isn't?

Knock Sensors. If they aren't working correctly, but electrically OK so there's no code. But that's a massive job and opens up a lot of "while I'm there I should do" things. Big snowball...

Thanks for asking around Mac.

One of the reasons I wanted to put in new pumps was that the X350 XJR that got the twinscrew prototype needed new fuel pumps, and it was also a fairly high-mileage car. So I figured after 10 years & 108'000 miles they wouldn't be at their best.

As it turns out, I can clearly hear the new pumps whirring away (with the back seat and plastic plugs out) and hear the fuel being pumped in the lines, whereas the old pumps were not really audible, there is a clear distinction in the sound between old and new. So that makes me feel a bit better.

I think i'll also reflash the ECU, at the very least that will clear the adaptations...

 

I've got the opening post open, because I'm confused as usual.

A couple of random thoughts first:

-- is the IAT sensor working properly?
-- is the TPS synchronised with the physical throttle plate opening

I'm sure of the Schrader valve, but not so sure about the alternate locations
shown in the picture. I would be careful to ensure that they are indeed what
you suspect they are.

Speaking of fuel lines. What if some flexible part of the fuel line has developed
a flap in the inner surface. When that happens with a brake flex hose it can
chop off backflow and cause a mysterious sticking caliper. What if in your
case a flap cuts off fuel flow at higher demand?

A mechanical fuel pressure gauge will completely clear that mystery.

On the AJ27 4.0L SC, fuel pressure is specified as 3 bar over boost IIRCC.

Therefore, for a fuel pressure gauge measuring against atmospheric as in
the case of the windscreen mounted gauge, it would be 3 bar + boost.

The intent on the part of the engine is to maintain FP relative to intact
tract pressure at 3 bar both for metering purposes and to ensure that
the injector pintle can overcome boost pressure.

Leading to, is your boost sensor working properly?

How does it run with the SC belt removed at WOT?

I would still log.

For one thing, some of the parameters are in play to some degree,
and you can log whether the vehicle is indeed in open loop.

All comments about FP are based on my knowledge of the AJ27 SC behaviour
with a smidgen of knowledge about the 4.2 you have.

 

In answer to your random thoughts Plums, yes the IAT is measuring, and quite accuratley. The throttle body calibrates itself every time you start the car, it cycles through close-open-close before it fires.

There is no boost sensor on these cars, the MAP is between the throttle body and the inlet of the supercharger. 15psi has been called out, because stock engines run ~13psi, this one has the smallest possible top pulley so ~15psi. Plus 55 + 15 = 70

Did some measurements with the SDD...man I wish I still had my Android phone, Torque was so much more user friendly...

Regarding the fuel pressure, no dropping off with the new pumps fitted, held ~480kPa (70.5psi) at WOT to ~5800rpm until I backed off because of the pinging. I doubt there is any problems with the fuel system.

Short & long term trims were fairly normal (from what i've seen in the past)

Wideband only comes in mA or you can look at the "equivalence ratio" (someone school me please) but both banks were more/less the same and hung around 0.8%-1.2%

Now, the MAF is where it gets interesting, here are screenshots from a WOT run in 2nd, starts off light throttle in 2nd about 4800rpm 90km/h and then nail it up to 5800rpm just under 120kmh

You can see the MAF rate jump when I get on the throttle, up to 311g/s @ 5050rpm, but it kind of flat lines over the next 800rpm, up to 332g/s @ 5770rpm

That does not seem right to me...



























Anyone know if that's a normal increase at that sort of rpm?

 

Sorry no time to read the whole thread so some thoughts anyway

Cheap Android tablet maybe?

Even at WOT the PCM relies on some sensors such as MAF and (er, I expect IAT/IAT2 and well, er, CKP? CMP?). Maybe one is weird (bad wiring or whatever).

I suppose a poor ground or sensor power might upset things, giving weird sensor values sometimes.

70psi fuel sounds a lot. Don't trust me on that but it just does - is it right?

 

Since you are guaranteed to be paying attention, I'll just mention that in
order to answer your post I have to first go to page 1 of the thread and
login. Logging in from the tail of the thread is always a failure.

Back to business ...

The fuel pressure report was using a mechanical gauge?
Don't want to rely on sensors that may be wrong due to defects.

If it was, I would write off FP as a problem for now. And packrat
the old pumps as emergency spares.

I cannot see the pictures from dropbox, so I'll work with your
narrative.

Keep in mind that I have no idea of what your MAF *should*
read. Maybe someone can take some comparison readings
to clear that up.

But, an under reading MAF will result in pinging because
the engine will freewheel with the actual air being received
while the ECM feeds only enough fuel for the falsely under
reported airflow as *seen* by the MAF. The result is a
lean mix = ping.

With your pulley, you may have crossed the limits of the MAF.

Or, the MAF could be weak, defective, dirty. One thing to
clean is the heater wire. The sensing is via the perceived
cooling of the heater wire due to airflow over the wire.

The other thing to be aware of is fuel injector duty cycle.
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.

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.

Do you have a flap in the airbox that is failing to open?

Intercooler pump, is it functioning? Overheated charge
will also cause pinging.

Engine coolant sensor?

Is the intake tube properly seated? Air bypassing here
will not be sensed by the MAF.

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

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.

++

 

I bought a cheap Android tablet but it was too cheap and it crashes with Torque running, and when it does run it's buggy....

Yeah 70psi sounds like a lot, but too much fuel can't cause the problems i'm having...

 

And on second thought ...

have you done anything to the intake tract upstream of the MAF
that would disturb the way the MAF "sees" the air flow?

Did you happen to remove any screen that is intended to reduce
turbulence for the MAF?