Hello all, this is my first post… I've been reading from here on and off for a couple years. Here is the issue that I am having: after a long Indiana Winter and a dead battery I decided to get the Jag up and running. my car was running a little rough and idling a little high...so I decided to look at the coils and plugs, because I have had that issue before. It turns out I had a broken plug. The porcelain was literally snapped. Since that was the first cylinder I checked I thought I was in luck because it would be such an easy fix. I replaced the plug in the idol dropped down a little bit approximately 8.5 K in park. I went for a road test, But it still didn't have the power it should. I looked at the other plugs and noticed that oil had gotten through the seal and fouled cylinder three. So off with the top and the gasket...cleaned it up with solvent reapplied. The issue was still the same, but now the idle was higher approx 10k. The check engine light was on this whole time but since it had all the other issues I had it cleared so it would hopefully read the new issue. The scanner now is showing that it is the throttle position sensor. So here are my questions: 1. did the TPS "learn" a new position with the car running on 4-5 cylinders? 2. If I unplug my battery for a certain amount of time will it "relearn" the proper setting? Thanks in advance for any help!

 

1. I don't think that's how it works.
2. No.

What is the code?

You will need to take it to a shop that has jag specific software to reset the TPS. The only other option is to adjust the TPS manually. That means you loosen the two screws holding the TPS to the throttle body and hope that there is enough play to get it to the right position. If there isn't you would have to remove the TPS and use a dremel or something to enlarge the screw holes on the TPS.

Theoretically, if you took a multimeter reading from two of the three prongs on the TPS (I forget which two of three, but its a simple trial and error process) you should get a reading of 0.6v. That assumes it was properly set and no one used Jag software to reset the TPS to another base idle voltage...

Does this make sense?

This is all assuming that the TPS is in good shape and that the throttle body is clean...which I suspect it is not. If you have to remove the TPS, you'll be removing the throttle body. It's a great idea to take the opportunity to clean the thing out thoroughly at that point.

 

Thank you for the reply. It's not my scanner, I took it into advance auto and they told me it read throttle position sensor. About a year ago I cleaned the throttlebody (because I had a sticky pedal) it was running great. That was only about 1000 miles ago. It does make sense what you said about the TPS, it just seems weird to me that all three of those problems would happen simultaneously after starting it up from being in storage, unless one causes the other...at least that was my line of thinking...it's probably wrong lol.

 

Step one: Remove throttle body and clean it out. You'd be surprised how many problems that causes.

Step Two: Buy a code reader. You can by one for $15. I have this one and it works fine:


You can probably find one on eBay for less than $10.

 

Should it say Ford?

The side I had clean before

 

Blue wire is not connected. I'm fairly certain I didn't do that

 

It is indeed a Ford part, so don't worry there, but I'm pretty sure you found your problem. Reconnect that blue wire and I suspect you'll be back to normal. At least you won't have a TPS check engine issue...

 

Hooked it back up and it did indeed bring back the power. The idle is still a little high so I started reading the forums and it seems there is some(?) debate about a gasket/hylomar between the TB...I didn't put anything on. Do you think I have a slight air leak causing high idle?

 

Did you clean the IAC valve while it was out . There is a TSB on replacing the weak throttle return spring .

 

When you say 10k do you mean the idle is 1,000 rpm or 10,000 rpm?

 

I removed the tps before I sprayed carb cleaner, but I only concentrated on the throttle body. Should I take off the iac valve to clean it or just hose it down with carb cleaner? Should I use some gasket material to mount the TB?

 

I meant to say 1k but it is probably more like 1100 while it's in park

 

You're not gonna want to hear this, but you will have to take it to a shop with jaguar software to reset the idle.

Its a common issue with the AJ16 engine.

You can attempt to add something between the throttle body and the intake manifold (I did, and it's probably my thread you read) and you might want to replace the gasket at the IACV, including the little rubber o-ring. They're cheap things to do, and I would be curious to see if it helps, but I fear that you'll need the $150 reset.

Make sure you do what you need to do to the IACV with the throttle body off. Access to those little bolts is not direct and they tend to snap. If you have it off the car, you'll have free and clear access to get those bolts off.

 

Hold it upright to not get the cleaner into the IAC stepmotor as it can be damaged if it gets past the Teflon motor seal . I had my TPS off and didn't lose the 800 idle . But that's just my one example . You had one leg off in the wiring so it may have gotten thrown off .

 

Thanks to all who have replied! I plan to take the throttle body off again so I can address the gasket/grease seal... What is the general consensus of what material to use? I have: gasket material, grease, and high temperature permatex. Are these acceptable? Do I need to order a non-curing seal? While it's off I will clean the IACV... do I need to take it off? What type of cleaner is safe? I have: carb cleaner, maf sensor cleaner, and electrical contact cleaner. Which one is best? Do I need something else? I'll certainly take it to the shop if I do everything that I can. Seems like I already missed a few 😁

 

Might be able to get a red nozzle tube into the IAC valve body if the poppet is open without removing the 2 little bolts . You are looking to clean the actuating sliding surface of the poppet center post . A 9 volt battery will actuate the valve being mindful of the flammability of the cleaning solvent . Carb cleaner is good with the MEK in it but is very poisonous to your liver or kidney as it absorbs through your skin . You can elongate the mounting holes on the TPS while it is off and reintall it leaving the final torque for after you adjust to 0.60 volts . I did mine as the throttle body was installed . This may get the sensor in range and may avoid a reorientation .

 

I think it's better to take that IACV off if you can. I'd certainly replace the o-ring in there as you'll probably find it as thin and fragile as mine was.

if you search my posts, I think I mention what o-ring I used, however it was just one that I thought fit best from a standard o-ring assortment package I had previously purchased at advance auto.

I used hylosil (or was it hylomar?) between the throttle body and intake manifold. It's a blue non-curing gel that I would recommend using only to cross one more variable off the list. Permatex makes something similar as well, fuel and oil resistant, so it makes sense to use it there as you'll still get some oil blowback through the camcover hose connected to the air intake.

 

My IACV doesn't have a O-ring. No rubber o ring, just aluminum that sits in TB.

 

Mine does.

See the pic for where it goes. I used a regular rubber o-ring. I believe I also had the metal washer too.

https://winkay1.en.ec21.com/JLM12185...2_9589524.html

I would get a new gasket as well...part #JLM11490. Maybe use the Hylomar AF, or Permatex 85420 on both sides of the existing gasket instead?

I found my old thread.
https://www.jaguarforums.com/forum/x...ket-not-44083/

Just flip to the end.

 

I got it sorted out. There was enough play in the tps. It was originally .595 volts and the idle in park was 1100. I moved the tps as far the other direction as I could (very slight movement) .665 volts and idle is now st 800 in park.