P02E8 Diesel intake air flow “a” position sensor circuit low

[vijith555]

Originally Posted by drover

Going by your vids when the flap closes it is declutched from the drive and a spring closes the flap, it is opened to certain positions by a motor driving the cogs, therefore if the gear box is a bit cruddy the declutching/throw out release part could be gummed up and that would be why it won't open at certain times because the release is jammed in the close position and the motor can't engage bit like a dicky starter motor .... Probably won't find much info on it as most would say its broken and just buy a new one, I know Jeep does, could find its a bluddy plastic lever that's worn or bluddy pot metal lever ......
Just a guess of course.....

I could be wrong here but I think it’s the reverse. I feel like the default position of the flap is open and that’s why you see it spring open as soon as the power is cut off. Makes sense because when the car starts the flap needs to be fully open and it closes to certain increments when it needs to control exhaust gas coming in. I have been told the flap needs to be fully open for starting and most part of operation.

In my scenario this is why on the cold starts you can see the flap open before starting and then as soon as the car starts, suddenly the throttle body gets power/signal it closes fully again and then in a half a second realises it needs to be open and opens (the fault in my case and not normal). It’s like the throttle body suddenly goes to the last position before the power was cut off and then the PCM realises the engine is choking and quickly signals it to open again. My story every morning start now.

[TR Laredo]

Replacement throttle body gears are available here:

https://www.ebay.com.au/itm/124730093051

Definitely cheaper than replacing the whole throttle body assembly.


Cheers

[Jeeper6]

If they sell a kit it could indicate the gears can lose a tooth or even strip totally. Though it does seem odd with a 2018 build as it isn't very old.

In my scenario this is why on the cold starts you can see the flap open before starting and then as soon as the car starts, suddenly the throttle body gets power/signal it closes fully again and then in a half a second realises it needs to be open and opens (the fault in my case and not normal).

Could the ECU even be being confused after start up as there is no signal from the MAP being there is no manifold air pressure in the intake manifold on start up being the turbo is effectively not pumping air in?
Should the flap be partially closed after starting to draw exhaust gases from the EGR?

[drover]

Originally Posted by vijith555

I could be wrong here but I think it’s the reverse. I feel like the default position of the flap is open and that’s why you see it spring open as soon as the power is cut off. Makes sense because when the car starts the flap needs to be fully open and it closes to certain increments when it needs to control exhaust gas coming in. I have been told the flap needs to be fully open for starting and most part of operation.

In my scenario this is why on the cold starts you can see the flap open before starting and then as soon as the car starts, suddenly the throttle body gets power/signal it closes fully again and then in a half a second realises it needs to be open and opens (the fault in my case and not normal). It’s like the throttle body suddenly goes to the last position before the power was cut off and then the PCM realises the engine is choking and quickly signals it to open again. My story every morning start now.

Whichever but it still points to gunge clogging the release or it could be dodgy MAP neither would surprise me ................ only one way to find out...

[vijith555]

Originally Posted by Jeeper6

If they sell a kit it could indicate the gears can lose a tooth or even strip totally. Though it does seem odd with a 2018 build as it isn't very old.

In my scenario this is why on the cold starts you can see the flap open before starting and then as soon as the car starts, suddenly the throttle body gets power/signal it closes fully again and then in a half a second realises it needs to be open and opens (the fault in my case and not normal).

Could the ECU even be being confused after start up as there is no signal from the MAP being there is no manifold air pressure in the intake manifold on start up being the turbo is effectively not pumping air in?
Should the flap be partially closed after starting to draw exhaust gases from the EGR?

These are my taughts too after seeing what is happening with the flap during starting and shutdowns. It definitely feels like either the PCM/ECU/MAP is gone haywire and causing the throttle body to position the flap in wrong positions at the wrong time. And it is consistently happening at the same times too which makes me think the throttle body flap is not stuck. Now going by the code definition. it is also possible and cannot rule out there is indeed an actual electrical short on the position sensor of the throttle body that is possibly causing the flap to position incorrectly.

Just hoping it is not the ECU or PCM that is gone bad but I am guessing if they were, the car would have more problems. If it’s any other component other than the throttle body, the suspect is the MAP so far. I have a MAP on the way to me and cannot be sure till I see it if its the correct one as it was difficult to convince them to send the part number I wanted as they kept telling me the Bosch site has a different one for us which is incorrect.

Some days I think all this could have happened because of the amount of tweaking I started doing ever since getting my secure bypass cable and JScan. Like maybe I did too many customisations and screwed up the computer somehow. And there is something that happened like 3 weeks prior to ever seeing the CEL which I never mentioned before. I wanted to see if I could get the side signal indicators in mirrors to work like side repeaters (they stay solid yellow lit till you use the turn signal) during nights. So not knowing this needs an extra harness/adapter to work I enabled the function on Jscan but nothing happened. So I reverted it back after a couple of drives. But when I looked at the advanced diagnostics scan few days later I noticed one entry that said something about a short. Regretting I didn’t take a screenshot of it. So not sure if this ‘short’ could have done something somewhere. But the timeline shows the first CEL came like 3 weeks later so I don’t think it’s related. But it’s running my head when I remember. Again the problem is at PCM level and this was lighting so hoping it was not able to leave damage in this area. There you go that’s a confession!

[Jeeper6]

I have read many times that should you disconnect the battery totally, ensuring there is no power left in the electrical circuits, it should erase the memory in the PCM / ECU sending it back to factory default settings.
So I would gather that any changes you made from the default settings would be lost. Though...I stand to be corrected with that as I have never had the need to disconnect the battery...in this Jeep or my previous WK2, so don't know whether the changes I have made via JScan would be lost.

I doubt personally that superficial changes made via the OBD port would impact the engine sensor communications with the ECU.

I would never suggest allowing a Dealer to touch any Jeep, but maybe it is worth in this case having a Dealer just do a diagnostic on it to discount the possibility of ECU changes?

[drover]

Originally Posted by Jeeper6

I would never suggest allowing a Dealer to touch any Jeep, but maybe it is worth in this case having a Dealer just do a diagnostic on it to discount the possibility of ECU changes?

Far cheaper options, I think this thread has evolved into a saga of repeating posts............ clean, test, replace unless that sort of thing is done then the answer will never come about ............. of course most places just replace ....

All in all its just an annoying thing as doesn't seem to be causing drama with operation .... Changes set ups with any of these OBD scanners one must do one thing at a time and back up the original or at least know what the original is ......... one change at a time then shut down and reboot before the next one or you can be in trouble....... many versions of changes with year models as well so one size doesn't fit all , export can have different settings as well.....