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Showing results for tags 'stumble'.
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Trying to track down an issue I'm having on my 2013 TT. It has a stumble when accelerating in the 1800-2500 rpm range in basically any gear. If I punch it, it will sometimes act like a misfire. I've changed plugs and coils and looked for vacuum leaks in the front and rear of the engine but didn't find anything. I hooked up an Edge CTS to it and watched various parameters over the past few days but don't see anything obvious. Spark timing looks good and consistent, fuel pressure looks OK, Long term and short term fuel trims look OK (see below), and O2 sensors don't appear to be malfunctioning. Boost may be an issue as the CTS doesn't always read equal to the dash gauge (might be lag in time it samples the data). I checked hoses and don't see anything obvious and made sure clamps were tight. I haven't checked under the intake manifold for anything yet. So for data I never see the short or long terms get above +/-10%. Short terms go up when accelerating but then come back down to close to zero at cruising speeds or driving at a steady pace in the neighborhood. I've also sat at idle and revved to about 2500rpm with no load to watch them and once I hit a steady state they are almost always at or near 0%. So back to the boost readings, I will see about 0.1-0.3 on the dash gauge and watching the CTS readout it will only go to 3 or 4 psi. Sometimes when showing 0.1 or 0.2 psi on the dash, it shows 0 or 1psi on the CTS. So just to be sure I think I'll check the wastegate diaphragms for leaks and then the diverter valves next. On full throttle I see about 8 or 9 psi, peak at 10 once or twice so I'm not sure how much it's supposed to be making. But I can't keep it punched for long due to where I live. Any suggestions?