I'm not showing any codes with my BlueDriver scan tool.

96 VDP 4.0 has a high idle 1100-1500 depending on mood.

I've pulled the throttle body off and cleaned well and pulled Idle Control Valve from TB and cleaned that well. Cleaned up all wiring connections along the intake train. Two of the wires on the throttle position sensor plug looked like they had been spliced into at some point. Cleaned and re taped those wires.

Put it all back together and still have high idle. When I disconnect throttle cable and speed control linkage the butterfly seems to positively close, although my scan tool shows 3% throttle position at idle, and idle still high.

I haven't had much run time with this car, and I've been troubleshooting its other problems, so I'm assuming this high idle existed before I bought it. It didn't run at all when I bought it due to a shorted wiring harness in the trunk.

The car really runs smooth and drives nice now but high idle means having to apply brakes to cruise at less than 35 mph.

Any suggestions on how I can test components before replacing stuff?

 

The first thing I would do is to set the TPS calibration with PDU, WDS, IDS, etc.
Setup and Configuration, then choose NEW TPS INSTALLED? YES.

I have read about people cutting slots in the mount holes to 'adjust' the TPS.

bob

 

Is there a cost effective diagnostic tool I can buy to do the TPS calibration? Would a system like this work? Can the software be downgraded to work with X300's?

Jaguar Land Rover Diagnostics kit IDS SDD JLR 131 +138 + Cable + Laptop Deal | eBay

 

I have an old laptop with Windows XP pro service pack 3. How would I go about getting a copy of IDS 118.5?

I'm assuming I could interface the laptop to the car with this:

OBDII OBD2 Cable for Land Rover Jaguar Vehicle Communication Module VCM II VCM2 | eBay

Do I also need a VCM module?

 

Bob knows best! Likely, your car received a new ECU or TPS somewhere along the way, which usually leads to a mismatch in the calibration for the idle speed. The usual method was to have the dealer run the throttle adaption, but all of that equipment is long gone from dealer shops.

So find an indy shop with the equipment, or take a chance on putting it all together yourself (which would be cool if it worked), or cut slots to manually adjust the physical position of the TPS until the idle comes down. I think those are your only options. Let's see if anyone else can suggest more.

No actual experience myself with the hardware/software used, but you've probably seen the past discussions here about VCMs, IDS 118.5, etc.

Glad the rear wiring harness replacement got her going again.

 

+2 on Bob's and SleekJag12's advice.

It may be possible to assemble the necessary system to do the throttle calibration yourself, but there's a substantial expense and learning curve, plus a very real risk of bricking your Engine Control Module (ECM) or some other expensive component. The safest route would be to find a good independent shop with the equipment and expertise necessary to carry out the calibration.

The one thing that caught my eye is the fact that two of the wires to the TPS had been spliced or repaired. The TPS is a potentiometer, or type of variable resistor arranged in a voltage divider. The ECM sends a reference voltage to the TPS, and as the throttle position changes the resistance of the TPS changes, resulting in a varying return voltage to the ECM. The value of the voltage tells the ECM the position of the throttle. If the splices in the wires added any resistance to the electrical circuit, that could affect the ECM's interpretation of the signal and contribute to your high idle. A TPS calibration will probably resolve the matter.

Are there any signs the engine is running rich? How do the fuel trims look (there is some debate as to how reliable fuel trims are on X300s due to the early OBDII implementation)?

When you pull the vacuum hose off of the Fuel Pressure Regulator (FPR) and briefly crank the engine, is there any sign of wet fuel at the vacuum hose fitting on the FPR? If so, the diaphragm has failed, allowing raw unmetered fuel to be inhaled into the intake manifold.

Cheers,

Don

 

Thanks motorcarman. You were correct. I eventually found an indy mech that actually could do the TPS calibration on a X300, rather than just said they could over the phone. The car idles proper now. Recommendation goes to Bob at Import Auto Group in South Holland, IL.

I would love to acquire a copy of IDS v118.5 to load on my old laptop if anyone knows how to get one.

 

You can load the software but what are you going to use as a VCM???
Jaguar does NOT speak Windows.

bob

 

You mention attempting to obtain IDS v118.5 which yes does now appear difficult to obtain.
Jaguar Administration Bulletin 13/5/11 indicates that v126 would become available June 2011 & further notes that "module programming for 1996-1997 X300 will be supported with this IDS"
Am I correct in now assuming that v126 which is available for downloading at a cost of $50 to $70 would be suitable together with a Jaguar recommended VDI.
Jaguar does recommend Da Vina & I note it is freely available from $250 to $110. The cheaper ones no doubt are china clones but do look identical.
My only question is that the bulletin also comments for x300 that vehicle line fully supported apart from flash programming AJ16, AJ26 & A27 ecms.
I also note that Windows does appear to be supported by Jaguar.

John Herbert

 

The MONGOOSE type interface will not work with anything earlier than SDD 125.

The original ROTUNDA VCM will interface Windows XP and DVD IDS 42 (introduced in 2006) to something like SDD 130 or 140 something.

Lots of info and discussion here on the forum.

You might be better off trying to find a WDS. That will work from 1995 to 2006 and some Jaguars to 2008.

I have 3 WDS (PTUs) and have successfully diagnosed 2008 S-Type R modules. The WDS recognized the VID number as 2006 S-Type R so I agreed and it proceeded.

FORD GENRAD WDS are sometimes listed for sale on eBay and the software is easily converted to Jaguar (Same unit for Ford, Aston Martin, Jaguar and Mazda)

$400 seems to be the going rate for an old WDS.

bob