Running bad under half throttle. Need some ideas please.

[Africandude13]

Need a little help from you guys.
Having some issues with the engine under mild throttle (5-10) psi. It sort of sputters and misfires. Full throttle is perfect until I shift then it falls on its face for a sec. Almost like timing is being pulled. Also letting off the gas after mild throttle it bucks and jerks. If I unplug the MAF (brand new) it runs ok since it's in open loop so I'm guessing a sensor or something is bad but no idea which one. N75 and N249 are new. Dvs are good.

Could the MAP or 02 sensors cause this?

Car is currently stage 3 minus. Only been doing it for a month or so. Was able to get a random misfire code once but that's it. No other codes

[julex]

You have to log it .

[Africandude13]

That's what i figured. I tired logging it a while ago and I couldn't. Something with my ecu box.
I have my full AWE kit ready to put in. Hopefully it fixed it or at least let's me log it.

[zillarob]

Is it making chirping sounds and the vac gauge fluttering?

[Africandude13]

Haven't heard any chirp sounds. Will give the gauge a look tomorrow.

[Audimilo]

Is it making chirping sounds and the vac gauge fluttering?

I've got one that is. Rob your thoughts on this?

I Boost leak tested it to 15psi, no leaks.

under partial throttle it chrips and the guage is moving around , exactly as you asked.

[Africandude13]

Just got a CEL and codes P1113 and P0102.
could bad o2 sensors cause misfires under partial load?

[Zba]

I have something similar. Running 710n's only a few months old. I checked them anyway and they are good. Boost leak checked to 20psi-ish; ok.

I know a MK4 1.8t that has the same issue and another s4. The one commonality is the tuner. It's probably not a coincidence.

It hasn't bothered me enough to contact them either I just slightly adjusted my low load part throttle driving habits

[Africandude13]

I'm really leaning towards the O2 sensors. Since they would be ignored under full throttle which is why I have no problem there and am having issues under partial load where the o2 are being looked at.

[Timtheguru]

You have to log it .

This. Also, when in part throttle try to keep the foot in the same spot then look at the log for throttle position.

I had some similar issues until I swapped my throttle body with a used one that I thoroughly cleaned. After that I did a throttle body alignment and haven't experience the issue since. My guess is the throttle body is gunked up and sticking when it's trying to part throttle, or is not aligned right.

[julex]

I am going to guess that your tune is actually subpar. Meaning that you're getting torque monitoring intervention, a common thing with some older tunes where they drive fine without boost, fine WOT but anything in between is crap. It is probably underscaled as well adding to the problems.

[GKTS4]

I've got one that is. Rob your thoughts on this?

I Boost leak tested it to 15psi, no leaks.

under partial throttle it chrips and the guage is moving around , exactly as you asked.

Also curious to know what the cause of the chirping with fluttering gauge could be at partial throttle.

[Africandude13]

This. Also, when in part throttle try to keep the foot in the same spot then look at the log for throttle position.

I had some similar issues until I swapped my throttle body with a used one that I thoroughly cleaned. After that I did a throttle body alignment and haven't experience the issue since. My guess is the throttle body is gunked up and sticking when it's trying to part throttle, or is not aligned right.

I'll give the throttle a nice clean since it probably needs it. But why would it only do it in closed loop?

I am going to guess that your tune is actually subpar. Meaning that you're getting torque monitoring intervention, a common thing with some older tunes where they drive fine without boost, fine WOT but anything in between is crap. It is probably underscaled as well adding to the problems.

Thought about the tune but I've had it for 3 years now with no problems.

[chaos2984]

I'll give the throttle a nice clean since it probably needs it. But why would it only do it in closed loop?
Thought about the tune but I've had it for 3 years now with no problems.

Well in closed loop. The engine management system goes off a base map and then uses sensors as inputs to adjust the fuel to get to the "ideal" spot that the ecm wants it at. It looks at the maf IAT O2's to get you there to that "ideal" burn. But if you have a o2 sensor issue to where it moves but sticky and it will relay info but not correct info, it will confuse the ecm. The ecm will make the adjustments that it thinks is right but they are really not. The problem is that if the o2 sensor moves and is not stuck at either full high or full low it will take a long time to set a code.

But with WOT it takes the O2's and says hell with them and runs off a pre programed map int he ecm and keeps it on the rich side the whole time.

But drive it normally and have a buddy watch what your O2's and fuel trims are doing. See if the fuel trims are all screwy when the issue occurs.