Dookie

For the past year or so my 01 s4 will periodicaly surge or hesitate at partial throttle. No problems during heavy acceleration. Seams to happen when letting of the throttle when getting up to desired speed or when giving partial throttle to maintain a steady speed. Any ideas?

RolledMySTi

Any codes? Have you pressure tested?

ThirdStrike

I'm going to bet its misfires or detonation. check those plugs coil paks and ICM's. and like rolled said scan for codes

Dookie

Have had miss fire codes in cylinder bay 5 pop up every 3 to 6 months for a good while now and recently had a code about a high temp setting or something. Should I replace that one coil pack and see if that does it, how can I check the others? Do either of you know how accessible #5 is? What are the ICM's? Rolled mentioned a pressure test, would that be certain vaccume lines?

donromani

You really need to get codes for this one - With random misfires I wouldn't worry about your coil packs or plugs. This could be due to anything from bad 02 sensors to a boost leak.

All the cylinders are equally annoying to access (coil packs that is) - you need to remove some stuff to get to them. Don't worry about this for now. If you want to check coil packs you can just move the suspected culprit to another cylinder and see if the misfire moves with it.

A boost test entails hooking an air compressor to the intake system with a little gadget - you can build or purchase this. This allows you to add pressure to the system to mimic the turbos without running the engine. While doing this you listen and look for leaks. Professional systems use a colored dye mixed into the air that makes it easier to see leaks. Most tuning shops will have a system like this.

ThirdStrike

cyl 5 is on the driver side and is the middle cylinder.
icms are on top of your air box. hve a yellow and brown plug. one closest to your fw is the icm for bank 1(passenger side)
coil pak testing is just grabbing one from a known non-misfiring cyl and putting it into cyl5. see if the misfire follows the coil.
a pressure test is done by putting pressurized air into your y-pipe and listening for a leak.
damn u need to read up a bit. search!

CTAudiDriver

if moving the coil doesnt change the cylinder, try moving the spark plug and seeing if it follows, if it doesnt try moving that injector, if it doesnt follow you have covered the usual suspects and traking down the problem could be a PITA

Good Luck!!

Dookie

Ok, so I pulled some codes. Now I have soft codes for a P0118 Engine Coolant Temp Circuit High Input? And a P0300 Random/Multiple Cylinder Missfire Detection. Not just cylinder bay 5 anymore. Looking back at past posts Captnops had a P0300 code problem and said he is having a bad crank angle sensor replaced. He wasn't getting the surging I do but some other code or dash light.
Sorry I am pretty lost with component terms and don't know what a PITA is. From random soft codes to the surging which is sporadic and of course wouldn't act up the last time it was checked out, I guess I need to bring my stripper into the shop to throw some money at?
I will go over all the suggestions and ideas I have gathered from you all with a pimp and hopefully not get raped. Anyone know of a good shop in the DC Northern VA area?

shawnoc2003

How many miles on the car? I'm assuming you have it chipped - Who's chip?

CTAudiDriver

I would try replaceing the coolant temp sensor, is your coolant guage acting strange? The coolant temp sensor plays a significant role in the Air fuel ratios the ECU (Engine control unit) on these cars.

The sensor is located behind the motor on the passengers side. theirs a vire with a square connection coming out of it. If you have the green sensor its probably not the problem but they did revise the sensor from a black or blue one I believe at some point becuase it was faulty.

This should help
https://www.audiworld.com/forums/sho...php?p=14018138

Oh yea, PITA = Pain in the ***