However it's not a V8, it's the same 4.0 straight 6, AJ16 used in the X300 cars.

 

Give a slight tug on the wires coming out of the ECU connectors , this is a total now broke wire commitment

You can pull the rubber individual wire seals ( spray lube first ) on the back of the connectors and give a peek , my wire seals were missing

 

Will do when I have the car here next, probably tomorrow or Friday.

 

Update....
I checked the ECU pins, no corrosion.
So I bought another ECU from a Jaguar XJS breaker.

With this one fitted it DOES go into closed loop mode - from the picture below you can see 'CL' at the top (was 'OL' before) and I can see the O2 values changing up/down as they should.






However....
You may notice that the engine speed is at 981 there. And that's the lowest i've seen with this ECU, after a few stop/start cycles it sits around 1300rpm!
I've discussed it with the ECU seller, who thinks it's an issue with the idle control servo, however I think unlikely as it idles fine at around 650rpm with the original ECU fitted.

I've noticed a difference in part numbers, which might be relevant:
Original ECU is p/n: LHE1410EC - and is dated 1096
Replacement ECU is p/n: LHE1410BH - and is dated 1295

So either:-
- The replacement ECU is 'good' with regard to O2 feedback and closed-loop operation, but has a fault in regard to idle control,
Or
- Because of the different part number (and being a year older), the replacement ECU has some difference regarding the idle control, and maybe needs a different idle control servo to go with it.

Any ideas?!

 

Your TPS is fitted to the old ECU. What you're explaining is textbook need for a TPS reset. The TPS needs to know there's a new ECU....just like an old ECU would need to know theres a new TPS.

Any dealer should be able to do it. There are some shops with fancy equipment that may be able to do this as well. Takes minutes to perform.

 

I'm flagging the O2 sensor values

My ELM 327 authorization key went away so can't look at

Off the top of my head and reading , 3.5 ( ? ) volts the O2 sensor returns

The reader device may not switch to the uncommon Titania based O2 sensors

With respect to the IAC valve the replacement ECU may or may not have the R - 493 TSB done to match the updated or not IAC valve body

 

Maybe, but I don’t think it matters too much what values are displayed, the main thing is that the (replacement) ECU is now in closed loop mode.

Looking at info about that TSB here, it is related to EGR, which this (UK) car doesn’t have.

The suggestion from Vee above is interesting, and logical.
I found this thread mentions something similar, and a manual adjustment that could work also.
I’ll investigate both options.

 

True on the EGR

Vee had a suggestion of giving the IAC connector pins / blades a slight twist to make better connector , his suggestion was for the MAF but in this case similar IAC connector pins / blades

Good to see in closed loop ( with it's agreement / command ) but it is only as good as the O2 sensor signal given ( not a go to close loop command ) the ECU to calculate with for your fuel trims , mixed numbers target 0 . 0 but + or - 3.0 good in real world limitations ( pulse width time increments related to the file size of the ECU maps / data arrays

The O2 sensor return values are probably in the Jaguar 801S doc

 

Air / fuel mixture leaner than 14.7:1 – reference voltage high (maximum 4.89 V)

Air / fuel mixture richer than 14.7:1 – reference voltage low (minimum 0.015 V)

Reference 801S doc page X ( eyes bad now ) in the O2 sensors section in the AJ16 section

Wiring guide pin out sheet the same information

 

This information relates to your final engine regulation outcome of idle speeds

You can do the ECU orientation first but you may want to look at other variables beforehand as may not be addressed as they adjust the ECU and now you're biasing the ECU / TPS relationship to mask the other variables ( if those variables have an issue )

Within a year or so someone reported that he " recovered " his idle by cleaning the EGR valve body

There is a position sensor inside the EGR valve body that does give you a live data sensor position error value , target 0 , this is reader device PID label EGR_ERROR

The IAC does not have a position sensor to verify it has arrived to it's commanded position

But Vee has an IAC exercising / verification procedure

The smog pump has 2 check valves , one electrical solenoid valve inside the smog pump ( the electrical connector has a diode in it and saw once where the pigtail was burnt , and an external in the piping to the exhaust manifold a large check valve body

They have gone through 3 smog pump part # changes

suppose to run for 60 seconds only at engine start up , relay and 2 fuses involved

Then we come around to the EVAP vacuum system , with the AJ16 engine there are 2 systems during production , a single large rectangle box vapor canister or 2 , the single uses a Rochester valve and the 2 uses an electrical valve instead of a Rochester valve

This EVAP system correction does recover the idle from reading others ( mostly Rochester change as the electrical valve instead is few and later years and California manufactured with it )

When you pull the fuel cap off do you get a vacuum draw after engine shut down?

 

The idle isn't consistent.
Started the other day from cold, idle was around 1000. Drove ~45 miles. At this point the idle in gear around 600 and around 800 in neutral.
Left car for ~2 hours. Re-started, idle then 1600 and didn't recover for 45 mile journey home. Tried engine off/on, no change.

Following day, idle is back to 1000ish.
Today i've checked the absolute throttle position % with both ECUs (and engine off, but ignition on).
Both show exactly the same range, 11.8% - 92.5%.
Surely if the TPS value was out, it would show different values ?

Ran it for a few minutes on the old ECU, idle initially around 1000 then reduced to 750, by which point coolant was upto around 50C.
Swapped back to the replacement ECU, idle around 1200 again!

 

So we can say no need to put hand on butterfly shaft to ensure idle is at mechanical stop , throttle return spring comparison

Vee's IAC valve exercise ?

Slight twist of the pins on the IAC valve connector ?

ECU connectors inspection ?

The IAC is 4 wires at the ECU in a pic coming , missing 2 pinching tabs as the socket gripping the ECU pins , slight tug on the 4 wires as they enter the ECU connectors

Sockets Black # 3 , 16 , 28 , 29

 

It's on the end stop, yes.

I did the procedure in the workshop manual, which didn't help.

Contacts all good.
However I have made progress, will describe in another reply.

 

TPS value at rest was 11.8% (with both ECUs). I noticed that the old ECU didn't seem to compensate for engine load (EG AC on or in-gear) and the new ECU did. Maybe the old ECU was happy with 11.8% and the replacement isn't?!

Curiosity got the better of me.
I unmounted the TPS.
With TPS unmounted it read 1.2% - therefore the rest position of the TPS on the shaft causes the 11.8% value.
Engine wouldn’t start with it that low.

I elongated the mounting holes into slots, now 7.5% in rest position.
It now idles around 750rpm, which is better, maybe a little too fast still - but acceptable! Took it for a test drive, I can see it remain in closed-loop mode except for full throttle and over-run when coasting.

I’ll see what it’s like with a cold start tomorrow.

I guess it really wants calibrating if I can get system to do it, as moving the TPS must have reduced the value at full throttle, but that’s a minor issue currently.

 

Engine load can be a relationship between the TPS and MAF ( TPS wide open / MAF low )

The MAF will read 1.2 volts DC at the proper idle speed on the middle wire at the MAF connector

Proper MAF part # as there is a supercharged version ?

This as a separate thing to shift your ignition timing

 

OK, will check that.

I think so, will check it.
I've moved the car back to storage today, but the cold start idle was normal, so hopefully all good for now.

A friend of mine works for an independent Jaguar specialist garage, I spoke with him, he doesn't think their equipment goes back far enough to reset the TPS etc for this age car, but he'll check.
The car will go to visit him soon to check the tailpipe emissions - it was him who found the emissions were too high in the first place!

 

You need a TPS Reset. Just take it to a shop so they can perform the reset.

Make sure you have the VIN number of the new ECU. You’re probably going to need that for the TPS reset.

 

Here in Kansas City with the official Jaguar dealership's they no longer have the equipment in the years of the X300

There is an independent Jaguar shop that may , but I haven't checked them

The exercise we have been going through covers some bases before hand in my opinion and your knowledge base will be up to speed as you converse with the mechanic and the orientation devise toward resolution

I think of it as the cart before the horse

Your TPS was in reasonable range of X % against others ( this is a clue the issue may be outside a TPS orientation ) and may have to return it there to shorten orientation time at shop

The TPS can be adjusted with the throttle body still installed but takes some hand dexterity and patients



The specific ( on paper ) return signal on the TPS connector as it is still installed and at mechanical idle stop is 0.60 + or - 0.02 volts DC on the middle connector wire ( Green / Yellow color ) as it goes over the fuel rail ( nick insulation ) . you can do this with engine not running , key in run

See page 60 and back to 59 for the pin Black 105 - 12 values , you are ROW ( rest of world ) in England

jagrepair.com/images/AutoRepairPhotos/jagxj1996.pdf

There is a mechanical idle stop screw adjustment inside the throttle body and I failed to see it on mine , someone has the details on its proper adjustment and you would have to ask yourself if it was ever tampered with to open that can of worms ( to be squared before TPS orientation )


The correct part # for the MAF on the normally aspirated 3.2 and 4.0 liter is

LHE1620AA

And supercharged is

LNA1620AA , so it is close but different

Genuine Air Box-air Flow Meter-3.2/4.0 Litre (less 6.0 Litre) For Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic | Jaguar Land Rover Classic Parts

Verification of correct ECU part # as there are a lot of them , but they are the same hardware

Genuine Electronic Control Module-4.0 Litre (4.0 Litre,4.0 Litre (california)) For Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic | Jaguar Land Rover Classic Parts

 

Jaguar dealers no longer have the system to communicate with cars this old.
I've tried a local independent Jaguar specialist, who said they don't think their equipment goes back far enough to do it, but he'll check and get back to me tomorrow.

 

Vee has the test equipment number and and I think the alternate substitution as it came out later as he has one

Mongoose ?