Chipped b5 s4 hesitating and studdering help!!!!

[lil98civi]

Ok so 2 days ago i got my revo tuned ecu put it in and went for a test drive. Everything was fine boosted to 16 psi and held fine. It was fine for a couple pulls, then the next day as soon as i went above any boost (0-16) it would studder and hesitate but would make full boost which was very wierd. I saw that one of the vacuum lines from my diverter valve was very brittle so i thought it could be that and changed it, sames thing didnt fix anything. Im still running the stock diverter valves and its throwing no codes. Has anyone had a problem like this or heard of one what should i start with? I havent changed the fuel filter in a very long time so could that possibly help? It feels like its a misfire but no codes at all very wierd.

[drhoadsveersixx]

i had the same problem and so i just bought a new fuel fliter and got brk7es plugs and gapped them to 0.28 and did the fuel fliter and havnt had the problem. mine i used to be full boost and it would just fall on its face and the also would boost oddly

[lil98civi]

im going to do the fuel filter anyways just cause it should be done and i did do plugs about 4 months ago so they should be fine its just wierd that im actually making boost. It gets worse and worse everytime i hit it.

[BlkdoutS4]

you should also upgrade your DVs if you are chipped..

[lil98civi]

Yes i have 710n i have at my work i have to put in just have been too lazy until this happened haha. Would a diverter valve cause a problem like this and still make boost and no CEL?

[wunderman4]

I had a problem where the my car would stutter out around 4k rpms so I replaced the Dvs (034 Billet) the coil packs and plugs, and the N75 valve. They all helped a little but the N75 did the trick and fixed it completly so I'd recommend getting the N75, then Dv's, and if you start throwing codes for it the coil packs.

Hope that helps

[Dubluv11]

Yes i have 710n i have at my work i have to put in just have been too lazy until this happened haha. Would a diverter valve cause a problem like this and still make boost and no CEL?

you may have a fault code but no cel... but yes a bunged up diverter valve could cause this... install the 710n's and report back..

[Dubluv11]

I had a problem where the my car would stutter out around 4k rpms so I replaced the Dvs (034 Billet) the coil packs and plugs, and the N75 valve. They all helped a little but the N75 did the trick and fixed it completly so I'd recommend getting the N75, then Dv's, and if you start throwing codes for it the coil packs.

Hope that helps

thats the expensive way of diagnosing a problem..

[drhoadsveersixx]

i forgot thats were i started 034 dv's

[DonnieDark0]

When this happened to me it was the spark plugs. I replaced all and the studdering and hesitation went away.

[audimatt777]

I would have to agree with above.. I fought with misfire/hesitation problems for a long time. Finally switched my newly replaced plugs with Bosch F5DPOR (sidefires) and haven't had a problem since! my car is running 24 lbs of boost w/ meth

[JWatson]

Should pressure test too, just to be sure.

[drkenan]

You should read the diagnosing misfires thread and go from there. This car is way too expensive to throw parts at.

[lbs4]

it sounds like your car was stock. you liked the boost did a few pulls and ripped your throttle body boot! stock TBB's dont like all the extra boost from chips. so pull the clamp off and it probably ripped right along the edge of the boot.

[mys4.org]

Ok I need to correct some people here.. OEM recommend spark plug gap is .016 - .024 inches... I don't understand why people keep posting the .028 or .28 as that is not correct. Check with any Audi tech if you don't believe me. Also never believe a pre-gaped spark plug is correct. First check them before you install them. What I would recommend is first check and see if you have any codes. Likely you will have a random misfire. In that case take all of your spark plugs out and make sure they are gaped between .016 - .024 inches. If you do that and still have a problem you may have a bad ICM or coilpack depending on with cylinders are misfiring.

[MikeyB3]

OP, that's rookie! Get those DVs in there, replace your TBB and DONT take the 1st showcase on the Price Is Right!

[mholme]

Ok I need to correct some people here.. OEM recommend spark plug gap is .016 - .024 inches... I don't understand why people keep posting the .028 or .28 as that is not correct. Check with any Audi tech if you don't believe me.

I think that's because the factory manual does indeed call for this(it may be even smaller at .014) on the 2.7t, but I think this is an error on the manual's part. Most people, myself included set the gap @.028 for a chipped, K03 car and this is where OE suppliers set the gap(.032 most likely).
.28 is definitely not right