I'm trying to deal with a very high idle after refreshing the intake gaskets and cleaning the throttle body and intake tubes. Did not touch TPS, I double checked everything is plugged in. I adjusted both throttle cables and attached a new throttle return spring (the extra extension spring). New crankshaft position sensor brought it down from ~2200 to ~1800. Pushing the throttle at all and there is significant rev hang. I tried to adjust the little set screw but that went nowhere. Its inaccessible, and the steel grub screw seized to the aluminum casting and immediately rounded out. Looking for any last ideas before I take it somewhere and let them try to deal with it.

 

Gasket on the IAC valve ?

 

You will need a TPS reset. Not sure where you're located, but you'll need someone with a PDU, WDS, Mongoose.... you can do a search. It's a very common issue. Not sure what exactly did it, but cleaning the throttle body may have been it.

As a last resort, you may have disturbed the butterfly tolerance. For the AJ16 engine, it needs to be at .002", well at least when new. Whatever it was at, the TPS had probably learned that tolerance, overt time. When you cleaned it, you may have knocked the butterfly out of tolerance. Whatever you did, it altered what the TPS has gotten accustomed to seeing at idle, so it needs to be reset. I see you have the turbocharged AJ16, so that tolerance may be different.

 

Go through all of the above, but also double check you have connected everything back up correctly. I would go all the way back to making sure thei ntake gaskets are properly sealed and that everything on the throttle body is airtight, then make sure that the intake air hoses and sensors are all connected.
Maybe do a smoke test on the intake to confirm there are no stray air sources.
After reading the symptoms again, it sounds very similar to when I had a coolant temperature sensor fail. It might be worth checking that too.The expected temp/resistance values are in the forum, but maybe chek its connected first.

 

With the removal of the intake pipes

Check the EGR connector

Fuel pressure regulator vacuum line

Vacuum line hooked to under the # 3 intake pipe to the EVAP valve under the air filter box

Valve cover large vent line

Oil cap seal seated

Brake booster line

Your coolant temp sensor will read about 1800 ohms with a cool engine

 

Gasket on the IAC was fine so I left it alone. I had previously double checked all the electrical connectors and they were all good to go. Coolant temp resistance was 2200 ohms, engine was still a little warm from testing earlier. Brake booster line could be suspect, I've had trouble with that style of connector before. I didn't even think about the oil cap but that would absolutely leak air in after the MAF, oddly enough. Gave it a check and it seems ok? It doesn't have a rubber gasket just that contoured plastic bit to match the valve cover.

I also checked the cruise control linkage on the advice of someone on facebook. Loosening that helped a little bit but as the car warmed up the idle went back up. Rev hang was no better either.

 

Might be worth checking the shielded EGR hose under the intake manifold is hooked up ok. The one that goes round the back to the exhaust manifolds.
Mine became loose back when I changed the exhaust manifolds a few years back. The joints at the back became loose and just needed tightening up.

 

Seems everytime this comes up, people want to avoid the TPS reset which fixes the problem 99% of the time.

I would mention doing it manually, but with the supercharger, I don't know if you can access the TPS by hand, in place, with the engine running.

 

Last time I called around nobody wanted to touch the car, including the dealerships. The local "European Specialists" won't work on anything before 2000. Its just a pain to drive over an hour to get to a shop and hope that works.

 

The Jaguar dealer in Kansas City stated they do not have the equipment to support the X300 , as probably most areas

Hense the work around solution from the fundamentals of how it works , I'm not there yet

 

You could order a cloned mongoose from eBay. That would take care of it.

I'm not sure where you live, so perhaps there is a Forum Member with a WDS/PDU/VCM that could help.

 

Not familiar, what's a cloned mongoose?

...Never thought I'd say that.

 

https://www.jaguarforums.com/forum/g...station-41970/

It's basically a USB cable with a OBD2 connector on the other end that can interrogate your ECU. Also known as a J2534 cable.

This cable with the right software can reset the TPS, among other things specifically excluding resetting the LTFT, which shouldn't be very important to anyone anyways.

 

Oh I see, I had tried one of those for Toyota techstream but it wasn't working. I didn't really know what I was doing, so I ended up selling the laptop and J2534 cable.

I was able to make an appointment with Schearer's (a euro independent shop) this week so I'm hoping they can fix it. In the meanwhile I have checked the inside of the ECU for water damage, and it was perfect inside. I also replaced the Rochester valve because I noticed the fuel tank had been pressurizing, which was disconcerting.

 

anyone who still has a POS autologic blue box can do it

just get on the phone with every euro specalist and beg them

 

Which part # and manufacture for the rochestor valve ?

I have a Delphi ( GM ) number on a older computer and want to compare options

My tank also pressurizes.as I think the overpressure should exit through the carbon vapor canister

 

Here's what I used, the fit was perfect. Bit cramped but not too bad. I should've checked the tank after my drive to the shop but forgot.
AC Delco 214552
Autozone Duralast PV132
https://www.jaguarforums.com/forum/x...ntinued-81248/

Unfortunately I got news back from the shop, its not the TPS. But my transmission mount is missing and my shock rubber bumpers are toast and the alignment's all out. (Plus all the stuff I actually knew already)

 

I can't tell what the cause of your high idle was.

Are you saying the Rochester Valve was the culprit?

or are you saying the missing transmission mount?

or neither?

 

I was kind of hoping the Rochester valve would be the problem, but it wasn't. Trans mount they just happened to also find. Car was still idling very high for the mechanic today.

 

Thanks for the numbers

My transmission mount as the whole crossmember was cracked and I found a new one in factory wrapper on E - bay

Mine is normally aspirated with the more common transmission and there is a point where you would think some sort of mounting donut isolator thingy should be but this is normal from looking and asking around

For the supercharged engine with the GM transmission the crossmember is different , at least the part #

Link coming

My new crossmember is still out and maybe a pic later

Genuine Engine Mounting Bracket-rear-3.2/4.0 Litre (3.2 Litre,4.0 Litre,4.0 Litre (california)) For Jaguar Xj 1995 - 1997 (from 720125 To 812255) Classic | Jaguar Land Rover Classic Parts

The transmission mounts for the normally asperated as a post going into the central cradle that bolts onto the large cross member

For the supercharged GM transmission it is this

Genuine Engine Mounting Bracket-rear-4.0 Litre Supercharged-automatic (4.0 Litre Supercharged,automatic) For Jaguar Xj 1995 - 1997 (from 720125 To 812255) Classic | Jaguar Land Rover Classic Parts

They were going to have a 2.7 liter deisal option that didn't pan out and that may be the origin of the rubber donut

Was the rocherster plumbed in correctly as i read someone somehow put it in backwards