Well my problem started about 4 thousand miles ago somewhere around there
i have a s5 90 non turbo
My car upon start up shakes and rumbles seems like a vacuum leak right?
well after i start it up i gas it up 3k 4k rmp and the motor cleans right up doesnt idle rough much but if it gets below 800 rpm the motor still shakes so i got new spark plugs but wrong heat range i got 7 on both leading and trailing
but even before that it would do the same thing
i messed with acv or something like that its located above the throttle plates so i made it idle around 1000 to 1500 rmp
i would really like to fix this problem
i leave the car off after warm up for about 30 min and does the same thing
but if its been 15min or less it starts up fine
are my injectors leaking?
do i have a dirty fuel filter?
is my coolant jacket expanding after warm up?
idk
it does smoke but a little if i let it sit for a couple days
but idk exactly whats going on
I NEED HELP ASAP!!!!

 

Get the compression checked.

 

+1

if the engine has even remotely over 150k miles it could be done. easiest to get that out of the way first.

3 piece apex seals for the lose..

 

Sounds like it might be the Water Thermosensor which helps to dictate how much fuel is used upon start up. A cold engine needs more fuel to start up while a warmer engine requires less. Pin 2E of the ECU (Green/White wire) nees to have its voltage taken w/the car cold (key to on, engine off) and then after it is completely warmed up (engine running) and compare the values to FSM spec.

 

how much voltage should i be looking for? koeo and koer?

 

i believe a properly maintained 13b can handle up to 200k miles
but in this case it's at 127k i would still want to rebuild but only because i would like to street port the engine

 

and driving habits. spurts of spirited driving with the oil metering system often cause chattering of the apex seals which wear them prematurely. the stock 3 piece seals have a half sized top apex seal, which eventually can wear to the point of falling out of the seal slot. but in those instances the whole affected rotor usually nets 0 compression and the car is almost completely undrivable.

without a video of cranking and running all we can say is to test the health of the motor, which really doesn't take long or much effort.

if you want to bypass it and move to other things, i would suspect the fuel system. replace the fuel filter first and see what happens, next get a can of carb cleaner and spray it around the intake manifolds with the car running and cold to see if it smooths out any indicating a leak. worst case if the engine is healthy you may have faulty injectors which require partial disassembly of the engine externals.

 

You'll have to look in the FSM Engine and Emmisions section for the exact numbers. On an S4 they are 2 to 3 volts cold and .4 volts fully warmed.

 

ill check on alldata hopefully they have it on there i think i already have a ecu schematic, i just need a dmm thanks for the help, hopefully thats the problem.