Hi can anyone help?

I've got a 2000 S4 with Revo chip - but it's got a huge hesitation under full throttle. It happens around 3-4K rpm and is like someone momentarily touching the brake or lifting of and then accelerating again. When the car was first chipped there was no problem - then a big problem - the throttle body was ripped. Replacing that reduced the problem but it still feels like it must be damaging the engine. I've searched high and low on forums and on the advice of the revo dealer I've changed the MAF: - £180 - no difference; changed the dump valves: £150 - no difference. I've also installed Denso high performance plugs £100 - no difference. The Revo dealer and Audi say no codes are showing, Audi have supposedly also presssure tested the intake system to check for leaks in the turbo pipes - apparently no leaks. With the revo chip I can return the timings etc to standard - when I do that the car is obviously slower but there's no hesitation, similarly there's an intermediate program - that shows slight hesitation.

My guess is:
1. That something is failing under full boost or
2. That a sensor reading is off standard and is not being correctly dealt with by the Revo program.

But then:
1. The pressure test shows no leak.
2. No codes are showing.

My only option at the moment seems to be completely stripping the turbo hoses to see if they are leaking.

Any ideas/help appreciated before I spend more money and get nothing for it or blow the engine/turbos.

 

my car does the exact same thing, but when i put the stock chip in it stops(i have 2 seprate ecu's). i have done everything you have done and more and still it hasn't fixed my problem. i just took it to the local Audi dealership and they did $1100 worth of work. mainly replacing all of the o2 sensors. did not help a bit. they scanned it and no codes came up that would cause the hesitation. i am running OCT software from Stratmosphere and that has got to be what is causing it. i have upgraded turbos and everything and i have noticed that as i added mods and the boost raised the problem got worse. my best guess is that it is starving for fuel under acceleration. i contacted APR and may switch over to their stage 3 and see if that solves the problem or i may part it out and get rid of it and get something thats cheaper to maintain. let me know if you figure out the problem.

 

you should go with apr bi pipe. it appears there are no leaks in stock mode because not that much boost if being produced. the boot could have torn again, i ripped two within a month. bipipe solved the riddle. always look for performance shop. dealer will just charge you for what they "think" is wrong because they dont do performance upgrades very often. go to performance shop that is familiar with the hardware and they should know what to do with the symptoms you described. hope this helps

 

Have you guys tried changing the spark plugs. I had an A4 that did the same exact thing, after changing the spark plugs it was fine.

 

bobster - yep, tried the plugs, no joy.

brando_dtd - tried the revo performance dealer but he knew less than me, when it first went in i said i was worried it was a split hose and could damage the turbos, no he says and changed the MAF which made no difference.

slow s4 - in a way it's good to know it's not just me, but then of course i wouldnt want anyone to have this problem. my latest thinking is that if could be the f-hose, so I'm going to get a samco hose and replace it anyway. I'll keep you posted.

 

i had the same problem but when i replaced the dv's it fixed most of it and now it only happens sometimes

 

well, i bought a samco f hose from AMD, had to buy some clips separately. I've just been out to take of the old f-hose. i didnt want to take it off to examine and have nothing to replace it with. not an easy job i got the two ends off eventually but the middle was proving stubborn. with it still in place but more accessible curiousity caught me - and sure enough i could feel a half inch rip between the top and middle, just in the joint. well that's damm good i thought a) fingers crossed that it's the problem, b) i can definitely cut the one one off without pulling and yanking and damaging something else.

however it's dark now so i can't fit the new part. but the question now is how much did guildford audi charge me for a pressure test after which they said i had no leak. and this isnt even a small rip that might close up when not pressurised - hmmm.

can't wait to fit it tomorrow and see if the internet and a screwdriver is better and cheaper than a main dealer and audi tuning specialist.

 

and it didnt work. the problem is still there, it may just be slightly better. i'm rather depressed now. slow s4 - did you try anything else as well as the o2 sensors?

 

Well first maybe you have a loose conection where air can get out? Maybe check all the connections again, but it seems like o2 sesors may be the nextbest thing to check

 

i have done everything. let me run down the list real quick: silicone hose kit, new fuel pump, spark plugs, diverter valves, and o2 sensors. i have turbo upgrades and a full milltek exhuast. Stratmosphere changes their software with each stage of upgrades. so i have had mine changed 3 times and each time it gets changed the problem gets worse. i have had the car scanned on a VAG Com by the local Audi/VW performance shop and then at the Audi dealership and neither could come up with any codes that would cause a hesitation. they checked the MAF at the dealership and it was ok and i have checked for loose hoses twice. the only thing i havent changed is the injectors but there were no misfires so i dont think that is the problem either. i think the software is the only thing left that could be wrong. when the problem is solved i will probably be getting rid of the car due to the fact that when it is all said and done i will have spent almost as much on parts and maintenence as the original cost of the car. that may not be so bad if the car was running right, but its not. i spoke with APR and to change from where i am to their stage 3 it would cost $4400. anyway i think thats about all the help i can give.