doesn’t take 3 pages to explain this

the AJ16 ECM has a poorly implemented base idle adjustment system. to rectify this you can screw around with the tps holes or you can press one button with IDS and kick the can down the road.

 

you are correct, but,
it can also be helpful to discuss all the things that can cause the issue,
and potential other ways to fix it as some people will not have easy access to the unicorn tool and it will likely only get harder to find the tool as time goes on.
the more potential ways to fix an issue the better IMO.

i love a good discussion.

 

I am fortunate that I have the IDS/SDD/Legacy available on a laptop together with the required VCM to connect with the car, this enables you to carry out both the O2 sensor adaption and TPS adaption. I can assure you it does work.
Very disappointing that your proclaimed "Jaguar specialist" does not have this equipment available and was able to complete a TPS adaption.
Surely that should be completed before heading down the ECU replacement route, which from memory also recommends a TPS adaption after change of ECU.

John Herbert
1996 XJR

 

yeah i am a little disappointed it is not solved. I had heard many good things about him.
only good things.
and that he is supposedly the best and the man to go to.
really happy with the other work he did and it is clear he has vast experience and knowledge on all things jag.
If you were not so far north i would come up and plug into your laptop….

he did say that if i get a new ecu it would likely need to be programmed to my module and he could sort that if needed. So i dunno

 

On your black ECU connector the IAC valve sockets are here

Do you have any missing pinching 2 tabs in each socket ?

Do you have the dedicated ground strap on the case of the ECU to a ground stud ?

Vee had a suggestion of putting a slight twist on the pins / blades of the MAF and this could be done also for your IAC valve connector

I'm a big believer in good grounds and one ignored is the large woven engine block ground from the lower starter mount bolt

Best got from under with a 13 mm at the starter and a 10 mm on the car frame

I can't remember if the starter bolt has a nut on the aft side but the upper starter bolt definitly does

 

Setting your TPS back to factory spec isn’t going to help anything anymore. 0.6v was what it was set to over 20 years ago. Since then, the ECU has adapted to a new voltage for idle.

Adjusting everything, including the butterfly is a great idea if you were just about the get a reset done. I would strongly suggest you call around and make absolutely sure there isn’t a shop that has one.

I wish there was a tool that could be easily shipped out as a loaner.

If all else fails, I would take a chance on a Chinese clone from eBay for a one shot deal.

You could still adjust that TPS manually.

I think those are your only two options at this point.

If you chose replacing the ECU route, you would indeed have to snag the throttle body, with TPS from that same car, then you’d have to hope that it didn’t have a high idle issue as well, and then you might also have to mess around with the oxygen sensor plugs as well. It certainly could work; but there would be absolutely no guarantee it would.

I would much rather go with a Chinese Mongoose knockoff from eBay.

 

" You could still adjust that TPS manually."

You can play with it on one side or the other of your current TPS mounted idle reading that you spent money on someone orienting your ECU to

It can be done without removing the TB but takes alot of patients under there from the top down.

Make sure you keep track of the around 0.60 abouts as you naturally release the throttle as the mechanics settle down to the idle stop (spring ? )

A decision would be if to fiddle with something someone adjusted for you or the suggestion above on inspection and cleaning the grounds and ECU socket inspection

You observed an issue with the IAC valve , someone did find a alternate IAC valve and the question is if the shop you went to swapped out a same part # from a X300 as the final variable of consideration is the IAC idle position gap dimension and air flow through allowed

To know if the ECU is not commanding the IAC as it schedules down to the final idle gap is to read each of the 4 command wires

This would not be a calibrate verification but just to know you have a dead command leg signal

Your expected leg command signal is in the range of 0 to 12 volts DC

The IAC connector should not need to to be installed for this test

 

You do have a gasket on the IAC valve as it can be missing from reading others

 

well i thought he had the system and was going to do a reset. but apparently not.

i am trying to get in touch with someone to organise a rest.

not sure if i wanna go around playing with bending pins.

there was a gasket initially, the gasket is not currently there. however the idle is the same with or without it.
there is a good o ring in place and there is no leak from the seal.

you ae correct i don't really want to play with things as i know they are adjusted how they should be and i am hoping to organize the reset.
as if i start playing with things and moving the TPS maybe it will then need more than a rest.

certainly can check wiring and voltages tho

 

it is actually one of the mods here @Cambo who is the one in sydney with access to the system.
I spoke with him one time in the past and was going to organise him to do it when i had the car at the mechanic for the crank seal leak but then i ended up delaying that repair and using another mechanic.
Once i get back in contact with him hopefully i can organise the reset.

 

With the testing of the IAC command signal of the 4 wires you can look at them one at a time

bring the RPM up and let it settle down to idle and watch during this duration

one wire at a time will go through a change in voltages as the IAC schedules down to the idle position

No voltage present would indicate a bad ECU output

Do this for all 4 wires

This would require the connector stay installed as the engine behaves properly or not properly and other sensors come in play like MAF

Someone I think was Vee had a IAC reset procedure that may resolve things

A different IAC valve gasket would effect the poopet gap maybe and throw off the expected position and flow rate

Too thick of a gasket would be too large a gap and higher RPM , but you did observe a correct idle speed after a dead battery state a couple of times

 

And i did try the iacv reset procedure thing, and yeah the results were that it was opening and closing as it could reach low idle. But it was not staying there after finishing the test

 

So that rules out the IAC valve as it mechanically reaches the proper position

The drivers in the ECU are powering the 4 wires

so this leaves the ECU deciding how to manipulate the drivers

before sourcing another ECU determine what sources of information the ECU brings into the equation of how to drive the 4 wires

one of those is the rate of TPS closure or a definate idle position voltage reading before or at the null value of oriented 0.60 or near

and what flukes can interfere with these sources of infotmation

Grounds

Shorting coils to the coil wells should be insulated with the plastic shoulder bushings on the valve cover bolts but.....

the voltage value of the AC arcing signal getting into the DC signal sensor wires

Engine block ground

 

It seems that the IACV reset is more of a test procedure, at least for the AJ16 engine. I’m not sure how the AJ6 responds to the test.

Id cross off the IACV as a suspect. I know there should be a gasket and an o-ring at the IACV. The oring is rarely there, but adding it has never resolved any problems for me.

You really are a simple TPS reset away from having a good idle.

 

I don’t know why they want to struggle for absolutely no reason.

If they can’t get an IDS at least buy a launch clone like the thinkdiag I know it’s in there, works 100% on the GEMS wallet rovers.

 

it is not a matter of wanting to struggle or not.

it is a matter of being able to get the reset done.

there is only one person i know of in my city who can do it and i have tried to get in contact with them but have not been able to.
so until i can get in touch with them what am i supposed to do?


you say something here about thinkdiag launch clone or something? This is the first i am hearing about anything other than dealer level WDS being the option.
if you could provide info as to what i need to get, where i could get it and how to use it would be helpful

 

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

this is a great (but long) thread on WDS, IDS, PDU, Mongoose, VCM, etc. I know it’s long, but take the time to get through all 600 posts. You’ll learn a lot about what is out there to help reset your idle.

 

I will try to get the time to read it all.
hopefully there is some info pertaining to some equipment/software i can get to make it happen.

maybe the 4 pages worth of chat is worth it as it is the first i have seen of this.
i was always under the impression that i needed to find someone with a WDS and that was it. as that was all i reading over and over again.

maybe in there is an option as to something i can do

 

At the risk of perpetuating the eternal spiral, Spud, I take it you are happy that your TPS isn’t simply worn out? You mentioned that your mechanic “washed it out” , which if often considered the kiss of death, as the unit is not readily opened up to clean it properly, and cleaning it wouldn’t remove the wear.
Why not fit a new TPS, and see what happens? You are already racking up costs, and it is a much more logical step to take than replacing the ECU. Even the most fervent TPS adapters have acknowledged that it can and often does work straight out of the box without adaptation. Even if it doesn’t solve the problem ( my bet is that it will) it is worth eliminating it , and it is a de facto maintenance item as the car ages.

 

it is a potential option to replace it.
when i took it to the mechanic i was expecting one potential outcome to be “replacement of tps”
of course i can only go off what i was told and that is that the unit is ok.

and now i have just found out that it seems unlikely i can get a tps adaption i don’t think there is many other option. The option i thought i had to get someone to do it is no longer an option.
i just want to make it clear as it seems to get lost the only reason i am here looking for various potential options is because i am unable to get this tps reset done.
if i could i would have done it.

but maybe it is just best to stop talking about this topic and just deal with it and drive around with a high idle.
until maybe one day some combination of replacing ecu, tps and tb fix it.
or i rip the aj16 out and replace it with something else i can work on easier. Like a Barra. (Aussie Ford 4.0l I6 solid *** motor)
(but that just opens a whole other can of worms with security module and replacement ecu)