Spudmat, a closer, further look at your fuel hoses should reveal the fuel feed inlet hose coming up from the chassis side rail to the inlet connection at the rear of the fuel rail, this will contain a rubber section suitable for insertion of a pressure gauge.

When checking the Jaguar parts diagram I did discover they have the diagram nos back to front.

Their diagram shows No 8 as the fuel feed hose (PN- NNA6053BF)) and having a male connection, this should be No 12, the fuel return hose which connects to the FPR at the forward end of the fuel rail and has PN NNA6054BF.

The fuel return hose on their diagram as No 12 and showing a male connection, is actually the fuel feed hose and connects to the fuel inlet connection at the rear of the fuel rail. The metal tag on my hose (showing PN NNA6053BF) to the inlet verifies this.

So basically they have the diagram numbers swapped, handy for when purchasing these parts. No 8 is the return hose and No 12 is the inlet hose.

Parts diagram and location of fuel rail inlet attached.



John Herbert

1996 XJR

 

Sorry, parts attachment has male/female connections captioned incorrectly revised attachment.

John Herbert,

 

i mean yeah most certainly could be exhaust leak.
i am aware there is a couple cracks on the manifold.
i have done my best to seal them up with jb weld high temp exhaust putty.
the exhaust manifold bolts are tight.
under acceleration the STFT dropped into higher levels of negative and when backed off it would settle back closer to where it should sit.

would not have thought however that a slight exhaust leak could lead to the car running rich to the point that it could/would stall.

*pics incoming*

 

yeah i was looking at exactly this too.
so what it shows as #12, the inlet hose to the ear of the fuel rail, there is a rubber hose section.
so i suppose i would need to cut into this hose and install a gauge there.
i would obviously want to be 100% certain of the diameter of the hose so i have the right fittings before cutting the hose in half.

 

As long as the manifold putty is not separating from the casting skin

Exhaust donuts change to new , could be eroded ,easier said than done

Bed time in the States

 

just checked.
and see the putty has cracked in line with where the manifold crack is.

and whilst this is an issue that my contribute to some change in stft and some level of rich running.
it surely could not be the issue that i am having...

the 02 sensors only come into play once car is warm.
how could it be that a small exhaust leak would be causing extreme rich running on cold to the point of stalling?
surely an exhaust leak would be irrelevant at this point.
and even once warm, a small leak could surely only contribute a small amount....

 

pretty sure i have found what i need to install the fuel pressure gauge.
ordered now.....

 

43 psi at idle , 46 psi at throttle up changed by vac line

Your cracked manifolds are the elephant in the room , your point of up to the point of stalling is valid

Mine would run even at -25.4 and I was able to find manifolds in town as mine were cracked also

But I was not running under load on the road , just driveway runs

I did drive it home from the previous owner

 

yep.
i totally don't expect it to be 100% perfect without properly repaired manifolds.
but, when it is blowing black smoke and stalling that is certainly not the only issue going on.
the exhaust smells of petrol when car is cold.
when it is warm it no longer does.
so yes, whilst it is likely always running a bit rich it is only when it is cold that it is having the big issues.

everytime i have asked about manifolds at any parts guys i just get the response "yeah they always crack, good luck finding a good set".
suppose my only option there is to save some money and buy the extractors from simply performance in UK.
but they are not cheap to get and ship here.

 

To get someone to do the proper procedure before welding to give it a chance to not recrack is hard

You would have to build a very thick boiler plate mount like it is on the car and heat both manifolds and fixture in an oven

You can build a makeshift oven from cinder blocks and burning wood ( ? )

This reduces localized heat warpage during weld to not have a warped cooled down repair , and then you stress it mounting to flat engine block and your back to square one

This after you have grounded out and widened the cranks to receive weld down into cracks

Vee had a part # for the new generic donut gaskets that he gave me for mine that the number is somewhere in the garage , 60 mm pipe OD so the gasket is 60 mm ID , do not damage the on downpipe flange that seals the donut , 4 down pointing studs get in the way , new down pointing studs avail from Welch here in the states as there are many at the hardware store but not correct size , I can get you exact thread dimensions as have some spares off car and a tread size mandrel at the hardware store


Takes a welding torch heat to remove original studs from exhaust castings

 

While not impossible, I have serious doubts that the car would be so severely affected, during open loop only no less, by these exhaust leaks. Remember, at this time, the oxygen sensors are not being read by the ECU at all, so the car could not reacting to something going on in the exhaust piping.

The throttle body could be at fault here. I know this thread is long, and I should take a read, but has the throttle plate been cleaned? I mean, removed from the car and cleaned from both ends? I would then verify if the butterfly is indeed at 0.002"
when idle.

The intake manifold gasket could be suspect too? Maybe it's giving up and allowing unmetered air to get sucked in.

I strongly believe that the problem lies between the ECU, MAF and injectors. The fact that it performs well when the engine warms up and enters closed loop, means it's something that the engine can compensate for. The list of sensors being read is short, and the only sensor left in the lineup would be the MAF. I don't know if we ever confirmed it was working well....

Can we confirm that the OBD2 reader is showing RPMs accurately, when cold running? Does it match what is being shown on the dash?

During startup, when the engine is still warming up, have we tried disconnecting the TPS to see what happens?

 

I could be mixing my at idle -25.4 STFT readings between observations as I had both a totally missing vacuum hose from previous owner ( attached under and on the intake manifold around # 2 cylinder pipe ) and cracked exhaust manifolds since changed

The last thing changed was the exhaust manifolds

A ELM - 327 reading after only vac hose replacement probably was not done as the ELM 327 software authorization key expired after 25 uses as I learned how to reconfigure the PIDs and test runs / uses

 

Completely agree. Exhaust manifolds are a red herring at this point.

 

Have you checked the integrity of all the air intake piping downstream from the MAF to manifold? Any cracks, leaks, hose clamps not tight etc?

 

And the short vac hose on top of the FPR , the red arrow is exactly where I drilled a hole for fuel pressure reading

Capped off with putty ( or just kids clay at the dollar stores ) the brake booster vac line fitting on top of the intake manifold ? driveway test run only

There is a proper brake vac hose fitting release procedure I once saw , I think it is referred to as a banjo fitting

You have a suspect Inlet air temp sensor fitting

Gasket on the IAC valve as has been found to be missing

 

i agree exactly on the exhaust.

the throttle body has not beed removed from the car however has been cleaned fully whilst in the car. Opened and cleaned .
and yes it is fully closing and then also fully opening.
if it was not fully closing would this not just cause high idle?

the obd reading is slightly out compared to my gauge, it is out by 30-50rpm and that remains consistent across app rev range.
my app shows exactly the same as what a jag wds system does when connected.
so i believe the gauge to be just so lightly off.

i have sprayed start fluid all around the intake manifold and there was no change to idle so i do not suspect it to be leaking at all

i did voltage check on the MAF as per what parker said and read 1.26v at idle

i have not tried disconnecting the tps.

 

there is nothing to indicate any leak
an air leak there would cause excess air ie lean running tho correct?

 

Also just note. Whilst it may well be running rich all the time the black smoke and stalling is not consistent on every cold start.
it did not happen for a couple months. Then started again.
then it will happen for a day or two and then not for a week.

and yes parker i will look to get a gasket for the iacv however i do not believe that to be the issue as the ecu should be telling the iacv to open and close to keep the revs at target range.
so if itnis sitting a little closer it should just open a little more.
just got to find a gasket.


also i am trying to do many jobs atm so it is hard.
car is due for full fluid change.
brake fluid, tranny fluid and engine oil.
i need to get onto my rear handbrake shoes.
i am looking to swap my alternator.
removed the one from
my other car and cleaned it up.

also just questioning.
what does the secondary airpump that is connected to the exhaust do?

 

" and yes parker i will look to get a gasket for the iacv however i do not believe that to be the issue as the ecu should be telling the iacv to open and close to keep the revs at target range.
so if itnis sitting a little closer it should just open a little more.
just got to find a gasket. "

Air being sucked in is a concern , but it may be a negligible amount to effect vacuum

The IAC stepper motor may be a sequenced steps toward close to a final " fixed " idle opening and not regulating / modulating

The secondary air pump ( smog pump ) is run by a relay and a capacitor in the loom ( this loom can get fried ) that runs for 60 seconds only , there is a check valve / solenoid both inside the pump and a larger check valve outside the pump

There is more info in the 801s doc

I personally found a pump that was internally water damaged and stuck , there have been 3 part # changes for whatever reason

You can place your hand on it and feel for rumble at start up

 

Ok so here is a sample of two different behaviours of the fuel trims.

first is driving after cold start.
note there was no black smoke or stalling this morning.
car felt to run normal

second is once warm after i parked i revved it in park and neutral.
whilst both climb it seems warm was less erratic.

it seems that it does run more rich once acceleration is slowed/stopped.