Lack of power b6 s4 ant ratling at almost all startups..

[asimo]

hi guys.. im from slovakia and my english is really bad, i learned english just from playing games and HBO

i have a audi S4 B6, its an USA car.. not EU.. i have some problems with it.. iv heard from the problem of this 4.2L engine that the startup noise is random by many owners.. but my car makes it almost by all startups.. it is just a 1sec sound but i can hear it.. but the bigger problem is, that sometimes i have a lack of power.. i was on the dyno and cca. 80hp is gone.. but just sometimes.. not all the time.. iv changed the cams and the coils.. but the problem is still there.. i had some codes by reading the ECU.. missfiring problems by allmost all cylinders.. but it was bcs. the car was not started up for a looong time.. when i changed the cams and coils the misfires are gone.. i have just one code once a time and the engine control lights up.. something like the camshaft didnt come to the specific point or something like that.. (i try to find the code, i dont have the paper with the codes here..)i have my car in the repair shop and the engine is down.. so i need now help.. what can be the problem?? i cant see any broken parts or any problem with the tensioners.. pls help!!!

[norcal]

first things first, i'd do a compression and leakdown test

[asimo]

first things first, i'd do a compression and leakdown test

this problem would cause that one day i have the full engine power and another day not? and on the day after again the full power?

[Vee8s4]

Sounds to me that you have a code that's detecting an error with the camshaft position sensor. This sensor is responsible for timing events and controls ignition retard/advance. If this sensor is going bad and has an intermittent fault, it might cause the car to run TERRIBLY!

This will not show up in a compression test. Cam position sensors are located on the back side of the engine...in the center of each cylinder head.

Have the shop read the code to tell you if it's the right or left sensor and start there! Good luck man.

On another note...does anyone know if the camshaft position sensors are removeable without pulling the engine?

Thanks!

[asimo]

my engine is pulled out.. i have the code somewhere, but i can post it tonight when i find it.. the car runs smooth.. no vibrations.. just a terrible loss of power.. 100hp for sure.. but just sometimes for a long period.. one day its good and another its again 100hp gone.. and the ratling sound by allmost any startup.. cold or warm.. i think it can be the adjusters.. idk.

[asimo]

so the ERROR CODE is: 16405. i had allso codesL 16684, 16685, 16689, 16691, 16686 and 16690. but after the install of new coils and sparkplugs they never showed again.. just the first one: 16405 wit the engine control light lightning on the dashboard..

[BOOTNEY]

I think you need to check your tensioner if the tensioner bad it want keep the chain tight that the start up rattle the tensioner are hydraulic and post to hold pressure when car is cold, like vee8s4 said check compression first if that check out then its your tensioner and maybe guides are broke saying this i am thinking you have already check the topside coil packs etc

[Renga]

CODE 16405 = Camshaft Position Actuator A Bank 2, Timing Over-Advanced

VCDS / VAG-COM: uitleg - tips - trics

[TropicA4NoggyS4]

if you have it at all startups, i'd have it looked at.