Sold Jaguar XJR6 Double Madness - Double Sold

[Broadsword]

Yes, so ELA remains up for grabs if someone else wishes to dive in. Thanks for visiting Jag central Mr. Hooli. It was nice to meet you. I feel I'm getting a little closer to progress with the Turquoise Shed. I've come across a procedure someone came up for partially propping the inlet manifold in the air with all the fuel lines and cooling pipes still plumbed in, and thus getting access to the throttle body. I took the elbow off the charge cooler, which has revealed more of the throttle body. It doesn't look obviously broken but there is several millimetres lateral play on the shaft compared to ELA. There is less oily grubbiness in the intake system than expected, which is nice.

 

Interestingly while we were flicking through the many receipts in ELAs service history one of the service slips mentions diagnosing a sticky throttle and uneven idle. They then fitted a new throttle body (back in 2006). Interesting coincidence.

[bangernomics]

Who did the red bike sell to in the end? Need to add them to my follow list as have had a veto on xjr due to house apparently?

[Jazoli]

Who did the red bike sell to in the end? Need to add them to my follow list as have had a veto on xjr due to house apparently?

 

Me

 

Updates will be coming on the collection fred at some point.

[bangernomics]

Me

 

Updates will be coming on the collection fred at some point.

Add me to the list when it becomes available will you.

[Jazoli]

Add me to the list when it becomes available will you.

 

Might be best if you post on the thread as I will forget, Its not going anywhere yet though

[Broadsword]

Not much to say on this thread recently since I've been scratching my head wondering what is keeping the Turquoise Shed from running.

 

I took a deep breath and set about taking the throttle body off. It is a pretty tough job on a cold driveway. It isn't that the system is complicated, it is purely due to the way everything is crammed in there. My way of doing it was to remove the air filter box, MAF, ducting to plenum, the plenum itself, the elbow going from blower to charge cooler and the bit attached to the back of the charge cooler which joins the intake plenum to a large air hose below going direct into the throttle body. Access to the two 7 mm bolts holding the bit on the back of the charge cooler is nearly impossible so you need to take the intake manifold off. The charge cooler is welded to the intake manifold so with the manifold bolts off I elected to prop the whole thing at an angle in the air, which negates the need to undo fuel and coolant lines. With the manifold out of the way you can just about get that strange ally air duct plenum off the back and pull it off the air hose. It was fighting me every step of the way since the air hose was welded to the duct. It was then equally difficult to get the air hose off the throttle body. It looked like it has never been off.

 

The throttle body is bolted to the blower with four 10 mm bolts which came out easy. A little tug and the TB pops off. There is no gasket. Before that you need to disconnect the throttle cable but that is easy. The last step is to disconnect the coolant lines from the TB. Oh and don't forget to unplug the idle control valve and throttle position sensor. The coolant lines were particularly stuck and it took ages to pop them off without doing damage. After all that the TB was liberated, which felt like a victory.

 

Suffice to say the TB was very dirty. It was also partially seized. The idle control valve area was particularly clogged up with carbon. It took a while to clean everything up. I had the idle control valve out to clean that area properly but did not touch the throttle position sensor since it is either broken or working in which case me removing it would render it out of spec anyway. All I did with the TPS was look if the resistance value changed as I opened and closed the throttle flap. The values seemed to change from 500 ohms to 1500 in a seemingly consistent fashion. It seems to do something then.

 

On the end of the throttle body where you find the springs and quadrant for the throttle cable there was considerable play on the shaft. This appeared to be preventing the throttle flap from moving smoothly. Cue a box of fibre washers I had bought for £2.99 ages ago proclaiming they would come in handy one day. Now was the day. A couple of washers were ideally suited for taking up said slack. Now the cleaned up TB operates smoothly. Not much more I could do with it so the next day I put everything back together. Reassembly took about 2 hours, which is pretty good.

 

Nervous first startup and oh dear things have gone backwards. The engine won't idle at all. Either keep your foot on the throttle or it will just die. Operation of the throttle pedal is now very smooth, however, and I suspect it can be revved more freely, but it was running rough so I just sort of kept things at about 2500 rpm for a bit.

 

I have also checked that the fuel pumps are working properly. If you crack the flue line open at the fuel rail, petrol gushes out so I think the pumps are working ok. Everything is still pointing to the throttle body so I have ordered a spare from eBay. At £60 including postage for the correct throttle body it is worth a go. Chances are the throttle position sensor is playing up. A live readout on OBD2 scanner was giving erratic numbers when the engine was just about running. Bouncing between 0% and 23% with me pulsing the throttle just trying to get it going. From my understanding at idle you should see 10%.

 

So no good news in XJR6 world right now. Got zero interest in ELA either, which is depressing. As soon as I put it on for sale, several inexpensive (mostly broken) examples have flooded the market, which might not be helping things.

[Guest Hooli]

That looks fun* to get too, no wonder it's never been cleaned.

[Broadsword]

There is another one of these out there for sale with exactly the same sort of problem, and I have come across a few suffering from similar issues before. I had a word with the owner of the other broken one for sale. He had done an enormous amount of work, replaced absolutely everything under the sun *EXCEPT* the throttle body on his.

 

Always exactly the same story: they sat for an extended period forgotten and start to run poorly after that. It's like a strange disease that these cars catch when they are neglected. It would quite nice to get to the bottom of this with that in mind. I think the last thing people want to tackle is the throttle body. Now that I've done it once I can get everything off pretty quickly again, not a real problem. If you subbed this job out to a mechanic you would loose a great deal of money hence people give up.

 

When the replacement throttle body arrives I will disassemble everything again but leave the TB plugged in and try to probe the voltage out the throttle position sensor, which I should then be able to compare to the replacement part. Ideally I would have a clone of the dealer-level diagnostic software, which lets you calibrate the TPS and probe all the modules properly, but I can't find one for sale that I'm sure will do the job.

[Guest Hooli]

Can you find out the values it should have from the manual? I've not read it to see if they are in there, I just know they are given for my bike to make the TPS easier to check.

 

Talking of the bike, I had a failed TPS on it years ago that passed every test & gave a smooth reading when tested. Yet it didn't work on a running engine. Turned out the ferrite core the coil is wrapped around had cracked so the vibes from the engine was moving it in & out of contact with the bit that swipes it. Just a thought if you're stuck for explanations.

[Broadsword]

The value should be around 0.54 volts at idle from my research. The workshop manual doesn't go into fine specifics like that though. I suspect that Jag technicians just plugged in the diagnostic unit and worked as instructed by the unit. I've seen a video of the procedure and the computer tells you what to do basically.

[bangernomics]

There is another one of these out there for sale with exactly the same sort of problem, and I have come across a few suffering from similar issues before. I had a word with the owner of the other broken one for sale. He had done an enormous amount of work, replaced absolutely everything under the sun *EXCEPT* the throttle body on his.

 

Always exactly the same story: they sat for an extended period forgotten and start to run poorly after that. It's like a strange disease that these cars catch when they are neglected. It would quite nice to get to the bottom of this with that in mind. I think the last thing people want to tackle is the throttle body. Now that I've done it once I can get everything off pretty quickly again, not a real problem. If you subbed this job out to a mechanic you would loose a great deal of money hence people give up.

 

When the replacement throttle body arrives I will disassemble everything again but leave the TB plugged in and try to probe the voltage out the throttle position sensor, which I should then be able to compare to the replacement part. Ideally I would have a clone of the dealer-level diagnostic software, which lets you calibrate the TPS and probe all the modules properly, but I can't find one for sale that I'm sure will do the job.

Have IDS/SDD but in mcr.

[Broadsword]

Do you know where I can buy one of those units and roughly how much they might be?

[bangernomics]

Do you know where I can buy one of those units and roughly how much they might be?

Old dell laptop, image of hdd (I'd use a new sdd), and a cable. Probably about £250 all in or less if you have the laptop and go with a crap hdd.

 

Trying to remember what the cables called as it needs a hardware signature akin to hasp

 

Google about for the jag cable, I should do a batch and bung em on eBay but nobbers. I've also got the MB Star stuff somewhere too and most LPG stuff.

[Broadsword]

I have an old Think Pad that might work for those purposes, it is slightly harder to determine what the correct dongle/cable thing is. Looks like there are/have been suitable clones out there. Software is probably the easiest bit.

[The Moog]

Fair play for you working in the cold - not something I would want to do today.

 

January is a bit of a tough time of the year to sell anything with people skint after Christmas

[Guest Hooli]

The value should be around 0.54 volts at idle from my research. The workshop manual doesn't go into fine specifics like that though. I suspect that Jag technicians just plugged in the diagnostic unit and worked as instructed by the unit. I've seen a video of the procedure and the computer tells you what to do basically.

 

Aye the voltage is more important than the actual resistance anyway as that is what the ECU will actually use. I'd assume if you can get a probe it when fitted that opening the throttle with the ignition on would show a smooth increase in voltage all the way to full throttle from a good TPS.

 

My bike not being very advanced gave the resistance to set the rough position of the TPS before checking the voltage.

[Broadsword]

Well, trying to sell ELA on an eBay auction went nowhere, but I’m not going to rush readvertising it. I think people will be more interested in the very cheap ones on there for the next few days. For the time being it will only be on sale here for the shitters price of £2800.

[bangernomics]

I have an old Think Pad that might work for those purposes, it is slightly harder to determine what the correct dongle/cable thing is. Looks like there are/have been suitable clones out there. Software is probably the easiest bit.

Called mongoose or something? I paid £70 for mine, hdd image was for an old dell so I that's what I bought.

 

I'll have a rummage about for you, weirdly the software was the tough bit to keep activated. Go beyond a certain update and bang it stops working and it's reinstall time. Go beyond a certain date, guess what...bang.

 

I reset the bios date on mine so it never moves forward according to the software. I actually wrote the date in sharpie so I wouldn't forget it as no Jag for a few months . Currently browsing the cheaper end after being told Ela was out of bounds.

[Broadsword]

No Jag = sad times. I’m hoping that going through this process with the Turquoise Shed might answer the question. “Should you risk buying a cheap XJR6 with strange running issues?” Also I think it is worth trying to save them since number may dwindle quickly. Many have been lost to racing and butchering for the glorious drive train.

 

Thanks for looking up the diagnostic thing. I mean having that sort of proper diagnostic software would be quite a luxury. I might manage without but the idea of being able to calibrate things, have proper live sensor data and to be able to real all the car’s modules is an appealing idea.

[bangernomics]

Not wrong, I literally couldn't have afforded to run my last x350 super if I didn't have the software. Every time a light came on or a gearbox limp happened or a handbrake wanted putting into service mode...blah blah blah it'd be £80 and that's the local indie. Perish the thought that stratstones would even talk to me for less than £250.

 

I'll look at making one up and if it's not financially appealing when done I'll bung it on the fleabay of misery.

[Broadsword]

While waiting for the replacement throttle body to arrive for the Turquoise Shed, I started dismantling everything I needed to get the TB off. When I started to crack off the intake manifold nuts and bolts I realized that on the back end of the engine a bracket for a couple of electrical connectors had accidentally got trapped between the manifold and the head. I immediately reasoned that this was why the engine was running worse after cleaning the TB. This was only spotted due to it being a bright day. I corrected the schoolboy error and put everything back together for a quick test run. The car fired up and settled at a highish idle (1500 rpm). Throttle pedal still feels good (might need a better return spring), so I went for a drive to get the engine properly warmed up. Besides it was nearly out of fuel. The car was still bogging down under load. I kept going though driving light throttle, which the car seems to tolerate.

 

Somewhere between fueling and getting home some ideas were formulating in my head. I had cracked off the fuel line into the fuel rail and found that there was ample fuel flow with the ignition on. Then I remembered that when I took the return line off it was bone dry. I had another look after it had been running today. The return line was still bone dry. Looks like it has been dry for some time. I also used my mechanic's stethoscope on the fuel injectors just to get an idea if something was amiss. They were fine and a multi-meter revealed the resistance across the terminals on each injector was the same. Then I fired ELA up, let it run briefly and cracked the return fuel line on the back of the fuel (LUCAS!) regulator. Sure enough fuel poured out. At this point the spare throttle body arrived in the post. Changing the fuel pressure regulator is easy to I will do that first.

 

TL;DR I suspect the fuel pressure regulator on the Turquoise Shed has failed in some fashion. I will substitute parts between cars ASAP.

[Broadsword]

I swapped fuel pressure regulators between the two supercharged cars today. Very easy to do: crack off the two fuel unions (17 mm spanner), pull off vacuum line (vacuum line checked and it appears fine) and unbolt the securing bracket (two 7 mm bolts). This widespread use of 7 mm bolts in the engine bay is quite tiresome I must admit.

 

The fuel pressure regulator off the turquoise shed was grubby looking on the outside but spotless on the inside. The regulator on ELA was full of debris surprisingly, and I mean A LOT. ELA is now happily running on the regulator from the Turquoise Shed (I think it is slightly smoother, but it might by my imagination). I think the fuel pressure regulator being below the fuel rail is a bit of a trap for dirt and it just sat there and accumulated over the years.

 

The Turquoise Shed doesn't run much different with ELA's fuel pressure regulator. It can settle at a very low idle at times now though, like 500 rpm. It still bogs down under real load, it could barely move under its own power today. So these symptoms point towards fuel starvation. An important observation is that no fuel comes out the return line even with the fuel pressure regulators swapped. I took the regulator back off the Turquouse Shed and put a catch cup under the fuel rail outlet, then turned the ignition on. A steady stream of fuel comes of for approx 3 seconds, then it is cut. I did this twice, then marked the fuel level so that I can compare the equivalent on ELA.

 

I also played around with the fuel pump relays. I can't find any blown fuses by the way. These cars have two fuel pumps. The primary is just as any other X300. It's relay is in the fusebox in the boot. Take it out and the car won't run. Both cars do the same, swap relays, no difference. Relays on both cars seem fine then. The car will run with the secondary pump disabled (relay for that is behind the battery for some reason), this was confirmed with ELA. My conclusion is that the secondary fuel pump is for heavy loads at full boost. There are plenty of comments on various forums, but I am only trusting my own observations on this as a lot of people's talk is pure speculation. The workshop manual really gives no detailed information on these sort of things. It doesn't for example cover in detail what the role of the secondary fuel pump is, nor does mention it is different from the primary. I suspect the pumps are identical and I do have a spare if it comes to it.

 

So before returning to the throttle body I will compare the fuel flow against ELA to confirms suspicions of fuel starvation. Then the first logical step would be to change the fuel filter. Then I might have to take the fuel tank out and have a look. It could for example be silted up somewhere, the pump might no be working well, or the pre-filter might be blocked. Who knows. Any of those items could have deteriorated after a prolonged period of sitting.

 

Bonus video footage: A couple of half-arsed 0-60 MPH runs in ELA because I had never done it. It was cold, wet and grip seriously limited off the line so it was sort of 1/2 to 3/4 throttle. The old GM box holds these cars back off the line compared to the X308 XJR definitely.

XJR6 0-60 MPH.mp4

IMG_5741.MOV

[Dan_ZTT]

Sounds like good progress. If you've got a spare fuel pump is the next step to swap that in then? I'm guessing it's not the easiest job but it seems the most likely cause of the problems.

 

I do very much envy you having a duplicate car to troubleshoot with.

[Broadsword]

Thanks. Fuel pump failure is a common issue on XJ40 and X300. I thought it would fail completely though, which is why I been thrown off by seeing fuel flow out the rail.

 

I think this project would have been pretty much impossible without an identical car a few steps away will all known working components. Really want to see the Turquoise Shed running properly. It would be quite and achievement for me with no facilities or pro skillz. Besides, no-one seems so interested in buying ELA. Cheap, more imperfect car XJR6s seems to be selling better. Another turquoise one sold a couple days ago on auction for £1400 with a noisy diff, some rot underneath, bumper hanging off and epic lacquer peel on roof and boot.

[Guest Hooli]

No fuel in the return line does sound damn odd. I think they normally run full flow through the injector rail to make sure the fuel there is cool, with all the excess going back to the tank.

 

Can you blow through the return line to check it's clear? If you crack the pressure regulator off the rail does fuel piss out to prove the rail isn't blocked?

[Broadsword]

Yeah, fuel comes out the rail when you crack the union to the fuel pressure regulator, and indeed fuel comes out the end of the rail when the ignition on. That basically confirms some fuel is being pumped successfully from the tank and that presumably the fuel rail isn’t blocked.

 

What I suspect is the case is with the Turquoise car is that there just isn’t enough fuel pressure to push through the regulator (there must be a trigger point) to the return line. I might blow into the return line just to confirm that isn’t blocked, but I’m pretty sure the fuel doesn’t get past the regulator at all. So at the moment all the cars running problems sound like a fuel delivery issue. I’m hoping it isn’t a combination of that plus say the throttle position sensor since things then get a bit hectic.

 

So my current plan, in a round about way:

 

1. Measure the fuel flow out the the rail on ELA to get a direct comparison between the two cars.

 

2. Assuming ELA delivers more fuel that the Turquoise Shed, then try hooking power direct to both the primary and secondary fuel pumps via the relays in the boot, in turn. I just want to hear them running.

 

3. If at this point I think the secondary pump works, I might use a jumper wire to force it to run, and disconnect the primary pump relay and see what happens. If the car runs well enough to drive better than previously, the there must be an issue with the primary pump.

 

4. Is the secondary pump is bad or it runs and the engine is still starved of fuel, the change the fuel filter.

 

5. Failing all else, remove fuel pumps and have a good look at them at the state of affairs in the fuel tank. That would be after replacing the fuel filter of course.

 

Once I have ruled out any fuel delivery issues I will return to replacing the throttle body since the TPS could of course be an issue.

[Guest Hooli]

T'is logical.

[Exiled_Tat_Gatherer]

Makes for excellent reading fella - I really appreciate the detailed write-up. Hope you can get to the root of it - deserved after all the effort and swap-fuckery going on.

I'm still gutted I couldn't step up for ELA.

 

Best of luck dude.

[Broadsword]

VICTORY!!! The Turquoise Shed Shuttle of Excellence is now derivable. It was freezing today so I didn't want to do anything too ambitious. The easiest thing to do was test the fuel pumps. I have a small power source you can keep in your pocket and just poke in terminals to test things. It's actually a battery pack taking 6 AA batteries, which is not 12 volts admittedly but enough to test some stuff just to get a vague idea of what is happening. Anyway I fed electrons directly into the two fuel pumps and could hear each working.

 

Knowing the primary pump feeds some petrol to the rail I thought what if I put a jumper wire on the auxiliary pump and let the two work together. With the jumper wire in place I fired the car up, reversed up out the drive and pointed the car uphill (we live on a hill so it immediately reveals the bogging down under load, which has plagued the car. At this point the car shot up the hill on boost! Fantastic. A quick test drive (video below) reveals it drives quite normally. Parked up again and let the car get nice and hot, get some heat in the cabin, put a few loose bits and pieces back in place and pumped up the tyres. Very happy with that, I can actually drive the thing. I guess it is a blockage somewhere or a bad primary pump leading to fuel starvation.

IMG_5756.MOV

[Guest Hooli]

Nice result!

 

I think you need to read up on when the pumps should be running to have a better guess at the problem, maybe the secondary pump should only cut in on boost but isn't? Mind you, with a spare car to hand swapping the pump to see if it solves it is probably quicker.