Good evening from Cyprus!!
Hi to all of you, i am Dimos!!
I am a new owner of an old lady, car lover (this is my 49th) and wannabe technician (would love to be a professional...!!)
I had no problems with my car since one day i decided to replace the fuel pump - previous owner pured some very bad quality petrol, as he said. Changed the battery too, but the issues (difficult cold start and shaking like a drunk train in idle etc) and codes starting to appear one by one, until i decided that hard reset was a good option, and so i did it. OBD today gives me only P1647, an issue i knew it existed since the beggining of my co-existance with this beauty. I don't think fuel pump needed to be replaced after all...
- Cold start is difficult
- Is this O sensor issue enough to cause such a poor performance when the car moves in low speed? when accelerating it "gaps", chocking like and it changes the speed after 5000rpm. It all becomes normal after 60Mph but when decellerating and steping the gas to change speed the problem returns.
- Does the "relearning" process after hard reset takes so long and is it so annoying?!
- I haven't change the sparking plugs but i don't know what and if the benefit will be...
- Today i spoted that dash light was fading out when steping at the gas to accelerate...

I apologize for my English, is not one of my strong points as you see -)
This is my first post but i am messing around quite some time and admiring your knowledge and the "bypasses" and "short cut" solutions you find!!!
Thank you in advance for your time and you kind help!!!!

 

Dear all, i am back!
So, today i did something because i was pissed off and i didn' t know what to do, before i remove the TPS and TB to clean them, as better as i could.
I started to uplug some of the sensors while the car was working and guess what: unpluging the Alternator light from manifold intake, the car stopped shaking and started to behave as a lady!!! i re-pluged it and there it was again, a delirious tremens!!!
I drove it a little unplugged, and it wasn't as good as it should but it was definetely better!
As far as ot concerns the TPS cleaning, it was dirt, very dirt, very very dirty. I throw carb spray, left it for a long time to dry, wiped as much as i could the intake body with a towel and rebuilded all as it was.
It now works better and i am wondering: is the "relearning" procedure after the hard reset a possible root cause to all this lean issue thing, when in low speed?

 

I think you mean the MAF (Mass Air Flow) sensor .......?




















Graham

 

I cannot locate it in this diagrammas, sorry... let me explain you, if i can:
as i am standing in the front of the car, looking at the motor, in the left side up - lets say next to the ECU, on its right side (toward my right hand) - there are 3 sensors, in the body of the motor. I unplugged the middle one, the one who has more cables and a wider plug than the 2 others. After unplugging it, the OBD says about Alternator Light something...
But i want to share something more with you: today, as i drove it, it gave the impression that the issue starts from the pedal. As a matter of fact, a few months ago i recall i had the same sence but i didn't pay much attention. Steping at the pedal it lacks, it chockes and it accelarates but poorly, forgeting to react like this from time to time.
Otherwise, the idle is perfect, it works smoothly, no shaking, easy start...
Tell me oh Graham, show me the light!!!

 

I CAN POST PICTURES, YES!!!
It wasn' tin the motor's body after all... sorry...

 

Dimos,

I've copied this topic from your Intro thread for advice from members with the same model.

Graham

 

Thanks Graham, I might be able to help Dimos a bit...

Hi Dimos,
I have the same 2.1 engine as you.
Your picture is good.....the plug you show as undone is to the engine's MAP sensor (not to be confused with the MAF sensor which is located in front of the throttle body assembly).
MAP sensors can get fouled too with recycled engine fumes being brought back into the intake manifold via the PCV valve.
Pick up a can of MAF sensor cleaner and clean your MAP sensor along with your MAF sensor.
Hopefully after a good clean the MAP sensor might make it behave normally, but if not you might need to consider replacing it.

Be aware too that our engines can develop air leaks in the vacuum fittings, T junctions and rubber or plastic hoses that go between intake manifold, brake servo, PCV valve and the electric vacuum pump (located between battery and shock tower on left side of vehicle). They can cause poor idle and flat spots above idle. You can detect these by spraying some "engine start" on suspected components to see if you get a response by the engine to the additional fuel. If you have removed the intake manifold previously it is very easy to damage and fracture the plastic T fitting in the vacuum line from intake to brake servo, as our 2.1 engines also have a small gauge rubber hose that goes towards the front to a module that controls an auxiliary vacuum pump to help maintain brake vacuum for our smaller engine models. I mention this as many participants of this site have the 2.5 and 3.0 version engines which among many other differences have different intake manifolds, Throttle bodies etc.

 

Goodmorning Mark and thanks for replying!!

I sprayed all over the place, there is no change in the behavior, the idle remains calm and smooth.
I moved gently all the T junctions and plastic tubes i see, nothing changes.
I removed the MAP and cleaned it, it was very dirty, replugged it but nothing, the car behaves better when is unlugged than when is plugged.
I removed and cleaned the MAF sensor, the TPS & TB, nothing...
No corrossion in the brake servo valve, as long as i cann check
I thought that may be is the pedal throttle sensor but again, it reacts properly, it is sensitive as it was.
I don't see spark plug problems, there are no interruptions and it generaly starts easy.
The idle is perfect, works so smooth, no sounds, nothing.
It is in a kind of restriction when it moves, it is like the air or the fuel or fuel-air ratio is not correct. And i think this is a MAP task, isn' t it?

Additionally, would be easy for you to send me a picture of this "... small gauge rubber hose that goes towards the front to a module that controls an auxiliary vacuum pump to help maintain brake vacuum", to check whatever i can check?

Thank you in advance Mark!!!

 

Thanks Mark. I should have recognised that as the identical sensor is fitted to the XK.

If the worst happens and Dimos' requires a replacement, the P/N is AJ82763. Bad news is it's 126 UKP from JLR but I did find aftermarket sources at under 50 UKP.

Graham

 

Hi Dimos,

I only mentioned the small vacuum tube and auxiliary vacuum pump as they are not present on the more common 2.5 and 3.0L engines mostly discussed in this forum.
I do not expect you have a problem with these at this time.
Based on your sensor isolation test, it is likely that your MAP sensor is faulty.
I see Graham has kindly posted a part number for your reference and a suggestion to perhaps look at aftermarket options as they are half the price of a genuine sensor.

Good luck and let us all know how you get on.

 

Mark my pocket is 92€ lighter, since I ordered the sensor, aftermarket. It's gonna be in Cyprus in about a week and I will let you know when I fit it and start the motor for my ride. I hope this will terminate both my search and my problems...
Best regards for now!!

 

I am hearing you......I am half way around the world and our dollar is worth only about 51 pence or $0.70 USD. So buying parts with our currency exchange rates is painful at the best of times, yet alone the killer freight and postage costs at the moment!
I am stuck with about $50 USD postage costs for anything I buy out of the US at the moment.....so I am carefully picking and choosing what projects to work on as there are few options for these parts in NZ or even Australia.

 

Here in Cyprus everything is so God damned expensive, and even if you find abroad something you're looking, the postage is almost as high as the value of the goods you're buying. E.g., I bought 65€ the sensor and 25€ for the courier, for something weighing 20 grams... Anyway, I prefer to see us as the lucky ones, capable of doing things on their own, saving money for the next project to occur. Hasta la Victoria siemper, we won't be defeated!!!

 

Good afternoon!!

Today I received the MAP sensor and already installed it. The situation is significantly better than it was yesterday, the car reacted really good when I started the engine and drove it. After a few hundred meters it did not respond well, but this changed again very quickly. It gives me the impression that it normalizes its operation, getting better than the previous time it started. I think I need to drive it for some kilometers and check how it responds, may be I am fooling my self that is getting better. What do you think, is it possible to need some time to reprogram or am I wish it would??

 

Hi Dimos,

Sounds like you are on the right track now.
If you want to clear any stored parameters of your ECM, you can pull F16 and F36 (both 5A fuses) located in the power distribution fuse box. Probably give it 30 minutes and refit the.
That should force the ECM to revert back to its base factory reference tables, whereby it will then begin learning local conditions and your driving habits again.
PDFB image below for your reference.

Let's see what the behaviour of your engine is after that ECM reset and after you have done some start and drive cycles to get the learning process underway.
I hope that is the answer to your issue.
You have already primarily eliminated air leaks etc. with your other testing.
The fuel pump is a simple device in our 2.1 variants, so no pressure feedback from fuel manifold to pump control or ECM. As long as you have suitable pressure (which I believe is likely mechanically set with a regulator bypass valve incorporated in the fuel pump), if you are having ongoing engine issues, you might be seeing if you are getting misfire codes for any coils or banks. O2 sensors can cause issues as well I believe, but again you would likely get codes thrown for out of spec engine emissions and codes adn warning lights for potential catalytic converter poisoning.

My car (which I had bought at auction with little known history on the vehicle) had an annoying "flat spot" just off idle with my 2005 2.1, which gave me poor upward gear changes when driving gently with not much throttle.
By default I changed air filter, spark plugs, cleaned throttle body, MAP and MAF sensors, exhaustively checked for air leaks on vacuum pipes and around manifold "o-rings" and did not find those common causes resolved my issue.
Engine oil and trans fluid changes done as well. Trans fluid was a good change resulting in better gear changes (didn't fix flat spot either).
I wanted to just reset all the general maintenance consumables so I had a good baseline on the car moving forward.

I wasn't happy with my TPS unit as it seemed vague in lifting RPM when the throttle body butterfly was starting to move off the idle stop.
Tracked down a suitable aftermarket TPS unit to replace my dubious one and that problem has disappeared.
I recently did a post to this forum for "replacement 2.1 V6 TPS sensor" listing the details of the sensor I found and used, if you end up needing to replace yours at some stage.
Jag only have the whole throttle body available (expensive if you can even find one), so just obtaining the TPS is a economical way of refurbishing your existing throttle body.

Good luck with yours, remember to update your thread so members know if you have resolved your problem.

 

So:
"...you might be seeing if you are getting misfire codes for any coils or banks" - No codes related to misfires or coils
"...O2 sensors can cause issues as well..." - a steady P1647 code, even if i removed it and cleaned it, propably needs replacement
"...air filter, spark plugs, cleaned throttle body, MAP and MAF sensors, exhaustively checked for air leaks on vacuum pipes and around manifold" - done
Battery, fuel pump, MAP & MAF sensors, all brand new
"...o-rings" - not done but after spray check, no bad response occured
"...Engine oil and trans fluid changes..." - not done but i had no issues, considering that i have extended previous experience with A/T cars
"...I wasn't happy with my TPS unit..." - removed it and creaned, it was very dirt
"...lifting RPM when the throttle body butterfly was starting to move off the idle stop..."- the throttle is perfect
THIS IS THE ISSUE REMAINING NOW:
"...an annoying "flat spot" just off idle ...... poor upward gear changes when driving gently with not much throttle..."

My old lady works perfectly, no shaking, no sounds, no issues. Just this annoying "flat spot" just off idle ...
God, where can i buy some oh this "good luck" you all wishing me for!!!!
Thank you for your pointings, thank you for you time!!!

 

Hi Dimos,

You can't clean the TPS as it is a sealed unit. Spraying some contact cleaner into and around the drive spigot receiver does not easily penetrate to the carbon track and wiper arm location internally, and generally only serves to dislodge the grease, so the TPS can then become higher friction in it's rotation and more critically its internal spring return.

The TPS units tend to get a worn carbon track in the critical area of most frequent activity which is the just off idle stop position.
No amount of cleaning will resolve the worn track.
Our TPS units are a very simple single track design as we are a cable throttle not "fly by wire".
Here is the thread I was referring to previously. It might be worth investigating a bit further if you are suffering from the "flat spot" effect as you come up off idle position.
You can measure the resistance of the TPS as you rotate it, and you may detect some erratic rate of change in the measurements as you reach a worn area of the carbon track.

https://www.jaguarforums.com/forum/x...petrol-248031/

 

Sounds like my kind of issues Mark...
where can i spot the OEM number, can you help with this?
Thank you!!!!

 

Hi Dimos,

From OEM you can only get the entire throttle body assembly for our 2.1 variant, which has the Jag part number C2S47882

If you are just wanting to replace the TPS sensor on the side, then you have to go aftermarket and I found that the Walker Products sensor (part# 200-1060) is a suitable replacement.
If you look at your existing TPS, you will probably find it carries a FoMoCo part number like F48F-9B989-AB, a three pin TPS with an offset connector. The throttle body has a flat metal prong spigot that reaches into the TPS to actuate it.

Note; When you replace it the TPS will not be on it's mechanical internal end stop, so you rotate the TPS a bit to engage prong then rotate to put in retainer screws.
Tip: put a rag under throttle body to stop any screws falling into the valley of the engine!
I also used a short interchangeable driver coupling and a crescent to access the restricted screws, easier than trying to get a normal driver with a handle onto them if you are doing the job in place. You can always remove the throttle body for easy access too.

Your idle will be naturally high either until you power clear the ECM, or let the ECM acclimatize to the new TPS (might take a couple of drives for the idle to settle back down to the normal 700-750RPM).

 

Do you think it is a good idea to repeat a hard reset before everything? i hate this provocated amnesia of my lady, i also hate the relearning time...
i am stuck and disappointed...
I did some search about TPS, nothing in Cyprus nor Greece... only used parts and i don't know if there is a point of getting something expensive and not knowing if it is in a working condition...
stuck in the middle Mark...