NVAKeith Posted June 17, 2022 Share Posted June 17, 2022 ‘11 LGT stock (OTS S1) USDM (6spd), yesterday after driving 30 miles I stopped at a light, foot off accelerator, as RPM dropped to idle engine surged once then it stalled. Restarted right up, driving away RPM fell noticeably fast when shifting 1->2 but otherwise fine. Next stop no issue. Another stop later I had to give it a little gas to prevent stall coming to a stop. Parked, checked for codes on accessport, there were none. Uninstalled accessport as first step troubleshooting. 8 hours later drove 30 miles it tired to stall once or twice but saved it by giving some gas. Today it stalled in the morning coming to stop while cold. This evening it stalled four times on way home. The third time it stalled I grabbed my phone and started videoing. As usual it started right back up, I gave a stab at throttle and sure enough it did its thang: rpms drop too low, surge back up on its own then stalls…video below -only happens when rpms falling to idle -happens hot or cold -ac on or off -doesn’t happen consistently Link to comment Share on other sites More sharing options...
silverton Posted June 17, 2022 Share Posted June 17, 2022 Try this: Disconnect battery terminals, touch them together for 30 seconds. Idle car for 20 minutes. Profit! Link to comment Share on other sites More sharing options...
dgoodhue Posted June 17, 2022 Share Posted June 17, 2022 My 1st instinct would be to check the intake track for leaks. Link to comment Share on other sites More sharing options...
Subsandwich Posted June 17, 2022 Share Posted June 17, 2022 Maybe check the throttle body. Sometimes they get gummed up. Link to comment Share on other sites More sharing options...
Fabsx Posted June 17, 2022 Share Posted June 17, 2022 Leaning towards possibly the coupling that goes from tmic to throttle body. What is your vacuum at idle/or boost from AP without AC on fully warmed up? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
xt2005bonbon Posted June 17, 2022 Share Posted June 17, 2022 Do you have a way to log ECU data (e.g. BtSsm app)? You could then check your fuel trims. You may have a massive vacuum leak or something like that. Link to comment Share on other sites More sharing options...
NVAKeith Posted June 18, 2022 Author Share Posted June 18, 2022 Thanks for all the tips! I agree seems like a vacuum leak, just puzzled that it isn’t consistent. I’ll plug the AP in and monitor vacuum next week. I do not have any legging devices… Link to comment Share on other sites More sharing options...
08SpecB_DE Posted June 23, 2022 Share Posted June 23, 2022 If it's not consistent, I'd start with cleaning the throttle body and maf sensor. If it persists, it sounds like the iac in the throttle body is going bad. Just recently ran into this issue on an 04 Forester. The problem was worse with the ac on. No codes, fuel trims fine, fixed some split hoses and nothing worked. At a stop, the idle would dip to 500 and slowly go down to around 300. A new throttle body and relearn did the trick! Link to comment Share on other sites More sharing options...
NVAKeith Posted July 8, 2022 Author Share Posted July 8, 2022 Thanks everyone for the suggestions! Follow-up: didn’t drive much for rest of June while I was down with COVID. Had dealer take a look while it was getting engine/trans/diff oils changed today. They couldn’t replicate issue but cleaned throttle plate and performed idle re-learn. Drove home with no stalls, hopefully resolved! Link to comment Share on other sites More sharing options...
silverton Posted July 8, 2022 Share Posted July 8, 2022 cleaned throttle plate and performed idle re-learn. other than cleaning the throttle body, that's what i told you to do Link to comment Share on other sites More sharing options...
Pleides Posted July 9, 2022 Share Posted July 9, 2022 Idle relearn will solve it briefly but you will eventually get some stalling. Just part of life with a vac leak on a turbo car. It sounds like you have a vac leak though. Most shops don't keep a pressure tester handy that can handle 10+ PSI that goes through a turbocharged engine. Go to a performance shop that has a dyno and they'll have one 100%. Still sounds like a vacuum leak. Unless you're on an aftermarket intake it's also highly unlikely the throttle plate is dirty. They don't get that dirty on these cars. Link to comment Share on other sites More sharing options...
kevin swick Posted October 29, 2022 Share Posted October 29, 2022 my car has the exact same problem i did the throtle relearn and it didn't work Link to comment Share on other sites More sharing options...
Pleides Posted October 30, 2022 Share Posted October 30, 2022 19 hours ago, kevin swick said: my car has the exact same problem i did the throtle relearn and it didn't work You probably have a vacuum leak. Take it to a performance shop that can high pressure test it. Link to comment Share on other sites More sharing options...
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