What is this thing? (pic)

The '92 and the '95 don't have it, but the '96's do. The throttle body is in dire need of a bath, but after a quick look, I don't know if it's mounted on the TB or intake manifold. Thanks.

TPS Throttle Position Sensor
:eeks1:


Dave

Nope, TPS is in the backround. Thats the MAP.

I don't know. Isn't the TPS on the rear of the TB, connected to the throttle plate shaft?. We're chasing a lumpy cold idle, so we need to clean the TB, and judging by the amount of carbon, I'm thinking cruddy IAC. Anyway, my son is under it right now replacing the rear brake line, so I'll wait till he's done. I want him to try to diagnose the problem.
Like I said, the '92 and '95 don't have this jigger on them, but they do have a TPS. Thanks...

962drrhino said:

Nope, Thats the MAP.

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That was my first guess. Is it part of the TB, or is it manifold mounted? Is it part of OBDll? Why do the two older ones seem to run better, and get better MPG?. All these questions.........

MAP sensor

Yeah it's the MAP sensor. Earlier years had it on the firewall with a vacuum hose leading to it, but later years had it directly on the throttle body.

Thanks guys! Now it's time to get dirty and pull it off.

All you should need is a torx or phillips screwdriver, don't be worried if you have to pull pretty hard to get it off - just work it back and forth while pulling, it's connected via a small right angle rubber boot/grommet/fitting. If you ever need a spare I have one on hand, part number 5602 8303 though it would take a day or two to arrive in the mail.

Well, we cleaned the TB, including the IAC chamber. Very dirty, but now all clean. Recent cap, rotor, wires, plugs (Champs). Started it up, idled nice for about 15 seconds, then started loading up. It clears easily, settles down, but then starts to load up again. If it had a carb, it's like the choke was pulled too tight. We're going to try injector cleaner, but does this sound like dirty injectors? This XJ is a Classic, with a very late build date, and the injectors are different from the other '96, possibly this car has '97 injectors.
As a side note, we replaced the hard and soft lines to the rear brakes. No better, still a hard pedal. Maybe time to look at booster, although it still holds vacuum. Any ideas?....

Sticky calipers maybe? Not sure, the only thing I've done with my brakes is replace lines and bleed them.

I wish it were that easy! Recent calipers, with nice movement when cycling the pedal. I went through similar problems with my '96 Country, all new hardware and cylinders, crappy pedal feel. A month ago, I finally got around to doing the hard line- very rusty, and the rubber one to the axle, just because it was old. Wow, now it has brakes! Feel great, work great. Now we try junior's car. So far, not so good It has new everything, all except the booster. I don't think it's the culprit, I'm leaning towards the proportion/distribution block beind dirty. Lots of crud when bleeding. It looks like another trip to Harry's is in order!

that makes sense too I guess - could be clogged up? I bet you could simply disconnect the current one, open it, blast it out with compressed air, and reassemble.

I think the worst brake line I ever saw was the one on a friend's dodge ram pickup - his brakes were always really weak and soft, and I kept telling him we needed to fix the darn thing before it blew up. One day it blew a whole bunch of brake fluid out the back end but we couldn't quite figure out where it came from, so we filled it up and bled it because he claimed it was fine shocked, the fluid from the rear right was pretty chunky and dark brown... a week later, the line just plain exploded. It turns out the hardline to the rear axle on the body was so badly rusted that the previous owner had "fixed" it by wrapping approximately ten layers of electrical tape shocked::scared::shocked::scared around it and then filling it back up with fluid. Two inches of the line disintegrated when I removed the tape... shortly after that a new line was installed, and suddenly the brakes were normal again...

kastein said:

It turns out the hardline to the rear axle on the body was so badly rusted that the previous owner had "fixed" it by wrapping approximately ten layers of electrical tape

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I hope it was at least Scotch Super 33, maybe 88? Not 'japwrap'.
When he gets home from work (he took his '95- a whole 'nuther story), we're going to bleed it again. I bet we find more bubbles. These beasts seem to have a special place to hide extra air, just to make them more frustrating. It took me almost two years of fiddling around to get my '96 nice. My '92 on the other hand just seems to respond to this stuff more straight-foreward. I was going to install the later dual diaphram booster and newer MC, but I just like the feeling of the older setup better. It has over 200k on it, and of the four XJs, it runs and stops the best! Go figure...

Booster test: pump the brakes engine off several times until vacuum is depleted. Hold pedal down hard, start engine, pedal should drop.

Yes, it does act this way. Could a booster fail softly? Im my experience, with engine off, you will typically get three or four cycles before you lose assist. This one gives one good cycle, second one starts to get hard. Sounds like it's starting to go?

Just an update on the brakes. Took a ride to Harry's on Saturday, got a booster from a '95 Sport, 54k miles (thanks Obama- orange paint on engine). Swap it in. VIOLA! Power brakes. Works great. The confusing part is that the old booster didn't outright fail any of the common tests for checking a power booster. I guess it was failing soft, slowly becoming stiffer. For $25 it beats buying a new one, especially if it wasn't the culprit.