USNNODOZ

Hey folks,

So im new to owning an Audi!! I just bought my first one, a 2002 A6 with KO4 turbos and a 6 speed manual. I have some issues with it i was wondering if i could get some help on.

1st off, I am new to the turbo scene. I know how turbos work and i have seen a lot of videos with turbos.

THE PROBLEM....
When im doing normal driving, aka not flooring it, it drives fine. i get no faults, no check engine light, no anything. runs and shifts smooth. perfect car.
However.... if i slam on the gas, it shakes... it kind of acts like it wants to go, but then sits there and shakes for about 2 seconds, then goes. once the boost kicks in, it halls ***. however getting the boost to kick in it just shakes, a lot. it does it at pretty much any speed in any gear besides 1st..

The guy i bought it from said that it was the Charged Air Pressure Sensor not being calibrated to the bigger turbo's? He said that the waste gates were opening up too soon and then shutting like they are supposed to before they reopen... i don't hear a bunch of rushing air, it just sounds like the engine is starved for fuel for a second, but i don't think its the injectors because it doesn't do it at the higher RPM's, just the lower one (around 2-3500k RPM)

I have an OBD-II reader, and I plugged it in. ive gotten a miss fire code P0300 only after it does the shuddering. when i put it on live data, and floor it, the check engine light flashes while its happening and the OBD says fuel system 1 and 2 are both " OL- FAULT"

im clueless ladies and gents. any guidance would be greatly appreciated!

Thanks in advance!!

KingHamer

I'll try my best but it does sound strange. I have the same car (K03). I would check all your spark plugs and make sure they are nice and snug. Mine was having similar issues and upon checking the spark plugs, mine was screwed in but a tad loose.

Your fuel system may be a little clogged, I would run one of those fuel system cleaners. Does wonders on mine. I use the Lucas brand, can get at AutoZone for a few bucks.

Your ECU may not be calibrating right, and you could try resetting it. Unplug the battery and pull the fuse for the ECU for 15 minutes. Reconnect the battery and fuse and turn the car to "ON" but don't start it, let it sit for 5 minutes. Turn the car OFF, wait 30 seconds, start the engine. It might idle and drive a bit rough while the ECU recalibrates to the engine properly, that is okay. Just drive it for 50 miles or so, don't gas it too much so that it can be consistent. Once the roughness subsides, you're fine to gas it. This worked for me, hopefully it does for you!

If all else fails, I would check the wires to the spark plugs and even do a test to see which cylinder is misfiring by pulling the Negative from the battery and then pull the Electrical connector from each spark plug wire. You're car should stutter for just a second. If any cylinders don't stutter, you know which cylinder is having the issue.

These are just some minor suggestions. Good luck!

johnkk

Time to invest in a Ross tech VCDS to replace your obd2 reader, so that you can monitor what's up with engine and see if the miss is only on one cylinder. Manual would help too. The shuddering could be caused by any number of issues. Not a bad idea to check all your plugs, just cuz Check for vacuum leaks. The wastegates should be fully closed when you hit it and the n75 boost regulator valve shouldn't be bleeding boost initially. There are two bypass valves up near the throttle body that "recirculate" boost when you quickly get off the gas to keep the turbos spinning when shifting. If these aren't sealing right this might cause the issue. Keep sorting and you'll find it.

bananahammock

This could have nothing to do with it but my A6 with K03's would have a fit when I floored it in low RPM's and it was because the SAI pump (Secondary Air Injection) was having issues and would throw a check engine light.

Car would be fine, my light would still be on and it would still drive OK, but it made a shudder and I thought it was the DV or something worse. I took the pump off and it was really hard to spin by hand (really, really rusted inside) and you can get some SAI delete plates and have a shop remove the code for the SAI from the ecu.

I would try the above suggestions to see if it has anything to do with a particular cylinder/misfire, but I would check your pump if all else fails. It's not hard to take off but beware the plastic hoses could crack while you're doing it and they're expensive to replace. The pump itself is also expensive if you just replace it.

All the SAI does (to my understanding) is warm up the cat for emission purposes.

johnkk

6MT does not have a SAI system. tip only

USNNODOZ

thanks for the input guys! After looking around on other pages and this one, the most common thing to check was the plugs. so... i checked the plugs.. the first one was an iridium plug and was gaped at .048. wow way off from what people were saying should be a .028. so i re-gaped it and pulled the next. same thing.. however, on the other 4 plugs i pulled, they were the ****tiest plugs i've seen. i'm talking lawnmower style plugs. in fact im not sure my lawnmower would even run with these things. so i went to autozone and picked up some NGK Laser Double Platinum plugs. a whopping $13.50 each. and put them in. went for a test drive. and wow. it fixed it. not a single bit of shudder or hesitation at all. the plugs were gaped at .028 straight from autozone, but i checked them just in case. i cant believe the guy did all this work to this car, the interior is literately spotless, coudln't fix the problem for 20k miles and all it was, was the spark plugs.

Future people- car runs like **** and studders and hesitates and gives a check engine light, check the spark plugs.

Big thanks to you guys for the help. i was worried it was an issue with the turbo's, but then again this is my first Audi and first car with turbos so. learning experience!

bananahammock

OP, glad the issue was as simple as that!

And Johnkk, if they don't have it, then someone must have modified my heads to accept the SAI pump sensors, and installed it on my car and coded my ECU for it...

I'm not sure where you're getting your information from, because I got mine off my 6MT C5.

johnkk

My 01 2.7 MT does not have SAI and Bentley says auto only...not that Bentley is gospel!! The 4.2 with auto in my wife's car does have SAI, and recently had a picnic with combi valves.