throttle body & fault code woes!!

[chappers_83]

my sisters leon 2002 1.4 38000miles, has a fault code 16891 idle high, shes also only gettin 15-20mpg!! iv throttle body taken out cleaned and cleared the fault and realigned, started it up n ran bout 15-20 miles n the fault code is back!!! so i then went n bought another throttle body thinkin it was knackered replaced and realigned it again n its jus came up again!!! bit beyond a joke!!! jus wonderin if any 1 nos of any other reasons there could be for the fault code???? only other problem with the car is a rattley exhaust buts its bin goin 4 ages before the code so i doubt it could be that!!! any help would be great!!!! shes eatin my ear!!!

[Crasher]

Check the coolant temperature sender output in Measuring Blocks 08, display group 001, zone 4 I think. Make sure it makes sense such as when the fan is on it says around 95 ish degrees.

[chappers_83]

sorry ment to say i had replaced that aswell, the dash is reading its working but ill double check that with vagcom. thanks

[chappers_83]

yeah the thermostat is working fine!!! kinda worried the car is getting 10ish mpg now since i changed throtttle body thinking change it back!!! lol

[mluton]

Did the new throttle body come with a new AIT sensor ?

[chappers_83]

not sure what that is! ????? it came as 1 complete unit, butterfly body and d end has black cover with electronic components inside

[Crasher]

The IAT is in the Thrust sensor which is in the side of the inlet manifold. You have VAG-COM I presume?

[chappers_83]

yeah i vag com, but theres no mention of that in the fault codes jus 16891 P0507 higher rpm that expected or sumthin like that anyway. do i need to reset that sensor or buy yet another part?? lol

thanks for your help by the way!!

[Crasher]

What is the engine code?

[chappers_83]

in work at d min ill check it out wen i get home.

[chappers_83]

jus checked, the engine code is bca.

[chappers_83]

sorry 2b a nusience shes being a pain about this car!! anybody got any ideas bout this problem!!! thanks

[Crasher]

Did you replace the coolant thermostat or the coolant temperature sender? If it is using that much fuel it should also give a lambda sensor error code. Get the engine hot and allow it to idle, go into Measuring Blocks 08 and then main group 001. What is the coolant temperature and is it stable?

[tdi miki]

have you checked for air leaks on the intake manifold?

[chappers_83]

replaced the thermostat, and thers no lamda probe error ill check the temperature tomorrow. as far as i can tell thers no leaks in the manifold none i can feel anyway.

[Crasher]

If you observe the coolant temperature when the engine is hot (fan running), I expect it will still say it is relatively cold, say around 60 degrees. You can’t feel for inlet an manifold leak, that is about as much use as doing a ritual dance around the car. The only way to check for inlet system leaks is by using a special leak detector spray whilst observing the lambda value in Measuring Blocks 08 to see if it changes and even then it will often fail to show a leak. One common leak though is on the servo pipe but I would expect a leak like that or even a manifold leak to produce a lambda error.

[chappers_83]

the VAG-COM readings are as follows:
RPM: - 720/min
temp: - starts @ 95oC then fan cums on n drops to 88oC
lambda:- bounces between 0.8% -1.6% but did go to -5.5% when fan 1st went on. but not 2nd or 3rd.

[Crasher]

Nothing wrong with those figures. Try going into Adaptation 10, group 00, read and save and then going back and re-adapting the throttle in Basic Settings 060.

[chappers_83]

did the above on thursday evening n at the min, touch wood, its worked so far!!! hopefully wotever that did has sorted it!

thanks for the help!!

[chappers_83]

the lights hav jus cum on again with the same error codes, trying doing what i did before but nout lights back on after 5-10 miles!! any idea whats wrong???

[Crasher]

Which codes exactly? Post the print out.

[chappers_83]

its the same code as before (16891 P0507 higher rpm that expected) havent been round to do the print out but its the same as above.