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.