Put my XJR back together after changing primary tensioners. Runs smooth, purring like a kitten. Drives fine, but, have had 2 "restricted performance" show up. Not every time I drive it. Seems random. Car has full power @ 13 psi with both stock pulleys, so I think both fuel pumps are working fine.

After the first time I did a hard reset.

After the second time I just turned off the car, then restarted it and the "restricted performance" was gone. Again, no codes while it read restricted performance or after. Filled it with gas and went for a drive with no messages.

The only thing I can think of was that I went down a steep hill with less than 1/4 tank of fuel and was turning some. This may or may not be relevant, I have no idea.

Any ideas?

 

WD:
In my NA XJ8, I would get RP with no stored OBD codes for a transmission fault. Apparenltly, they also come from Throttle body issuesw, since folks have reported no code RPs that were fixed by either cleaning TB connectrs or installing new or rebuilt TBs.

 

I'll check the connectors.

 

Dragon:
Ain't it about time for you to get AE with Jag extensions or VCM or Mongoose? There are only a few things you need to get to that the el cheapo scanners won't do, but the "other' modules can be important. Rading the adaptation tables might be enligtenng at your level of performance.

 

My buddy who lives very close just bought one.

My "hope" is that if I stop changing things, the car will remain stable for a long time.

I just put it back together a few days ago with the stock pulleys. Now I'm "only" running 13 psi of boost today at 70 degrees F. My original plan was to do the 1/4 mile with the stock pulleys, then swap back to the +4 lower and run it again, but after learning what a hassle it is to remove that pulley, and how busy I am these days, I want to just do as little to the Jag as I can right now and keep it as a reliable daily driver.

The car is a real pleasure to drive, especially if I'm not worrying about something possibly breaking.

 

Aw shucks. We were learning a lot from your experiments!

 

Look at the connector for the TPS.


Denso gold plated the pins on the TPS. Jag used tin plating on the terminals in the connector. There was a service bulletin about the problem. On customer complaint, Jag would replace the female connectors for the TPS.


If you find that the terminals in the connector are silver colored, clean the terminals with electrical contact cleaner and use a silicone dielectric grease in the terminals before reconnecting the connector.


While you are at it, check the terminals for the connectors for the two located on the left side of the throttle body.


This drove me nuts for a few months with intermittent restricted performance.


After cleaning and adding "BULB GREASE" I have not had any more trouble.


My car is a 99 NA AJ27, but bad electrical connections are bad electrical connections.

 

Via my 0-100 mph in 10.5 seconds video, I have successfully proven I've added 8-8.5 psi and approx 100 HP, at only $35 per HP.

What I've learned:

There is no good signal wire available to use a NOS controller, so without being able to have the safeties of RPM window switches I aborted trying NOS.

The nameless cats sound amazing, add approx 10-15 hp across the whole rpm range, but will not pass smog in CA. I tried them, and really liked the sound and extra power, but ended up deciding I didn't want to spend that kind of money for the HP/$ ratio and needing to swap them off and on at smog time.

I really like the akebono brake pads. The slotted rotors, not so much, they make far too much wind noise, I would never do the slotted rotors again, just solid disks with proper real ducting.

You can gain +4 psi without spinning the blower any faster by:
larger 92mm MAF, larger intake tube, bored TB, port matched TB, porting the eaton does make it run cooler and adds +1 lb+, running water injection @375 ml/min BEFORE the blower makes the air more dense and helps it seal better, making it cooler and much more efficient.

Then if you add a +4 lower, you truly get +4-4.5 more boost. My gauge stock read 9.5-10 as ALL 4.0s do. The 11.6 that is often mis-quoted is for the 4.2 motors which already come stock with a larger lower pulley.

I had 9.5-10 psi stock on my former 2002 XJR, and also on this 2000 XJR, per my gauge, then 13/14 with the above mods on stock pulleys, and 18/19 with the above mods and only a lower +4 pulley.

If you are running water injection, even at 18 psi, the stock spark plug heat range is good, the 1 step colder is too cold.

A $30 12" pusher fan from siliconintakes.com in front of the stock inter cooler radiator makes a big difference in cooling. At 18 psi I had less heat soak than when stock.

The car, in that configuration was a solid mid 12 second car, and that build can be duplicated for less than $3,500 complete.

Beyond this there isn't much more to try at this point without having to upgrade the rear end, stud the heads and add the 4.2 head gaskets to make it able to handle the extra power.

 

Here is an idea a guy on this forum suggested; I recommend it.

"My "hope" is that if I stop changing things, the car will remain stable for a long time. ";

 

Heh, yes, we will see if this Zebra can change his stripes

The boys at Muppet Labs will have to put their innovations to use somewhere else.

...but if I just change this one last thing......

 

You guys were right!

I cleaned the connections and added some bulb grease. No more restricted performance

 

After owning "baby" for a few weeks I had a restricted performance come on yesterday afternoon. It ran rough under heavy acceleration, but after 5 minutes the light went out and she ran fine again.
Assuming I'm going to get this again () and that I'm somewhat mechanically challenged:
1. What is the TPS connector and where is it?
2. Where is the TB connector?
3. Anything else I need to know regarding fixes for this previously mentioned?

Thanks Gentlemen

 

I have attached some photos showing my connectors. One of my connectors has silicon tape around it because the latching system was damaged.

You will want to remove the intake tube so you will have better access to the 2 TB connectors on the passenger's side. Then remove the connectors for access to clean them. I used a spray electrical connection cleaner, then some bulb grease applied via toothpick over the female holes on the connector, since I had better access to that side. Might as well do all 3 connectors, which is 2 on the passenger side, and 1 on the drivers side.

I'm able to get my skinny little monkey hands in there to grab the connectors. I use a flathead screwdriver to push on the tab locking the connector in place, then wiggle and pull the connector off. They snap back in place much easier than they come off.

Now that you own a Jaguar, you will NEED a code reader.

 

Why is the coolant hose to the throttle body bypassed?

 

I was wondering if anyone would comment on that...

I ask why not?

The car is never exposed to freezing temps here. Example, today is 79 degrees F.

I didn't see the need in heating the TB.

Could this cause any problems in 70 degree weather?