Ok so I had this problem before messing with things, but it seems a bit more pronounced now. Just as a Stage 2 with nothing else it did it on hot days in traffic. The set up now is a Stage 2 wrx with ST, upgraded top mount and a heat shielded intake. Since summer has come around I have been having an issue where the revs will raise up to like 1.5-1.75k when I get stuck in traffic on hot days. Has anyone experienced this? I did a search and was not able to come up with anything. Any pointers from other ST users out there? I checked everything for any type of intake leak and was not able to find anything. Intake has been tuned for, but the odd thing is it seems that it was made worse by adding the heat shield...the only thing I can think of is when I reset the ecu it went into learning mode again and with the heat it is throwing the system for a loop.
When you have EXTREME intake air temps, the engine will go to a high idle mode. I have experienced this many times on cars with 'hot air intakes'.
Gotcha, any thoughts as to why the heat shield made intake temps go down but made this happen more often? I guess it could just be that it has been hotter out the past few days...air intake has been around 106 degrees with ambient being around 96 degrees.
Oh sure, it rises. It rose with the stock box. The weird part is that it will remain stable while sitting there in traffic and then when I move forward and elevate the RPM's when it goes to come back down it will sit a little higher...then a little higher the next time I move...then a little higher again until I get a nice long stretch of road to cool things back off.
thats normal higher ? what is the temp ? you do not start effecting the tune till you hit the threshold of your tune (whatever that is) there is a table for that
I am not sure the exact temp as I have never been logging when this happened...don't keep the laptop with me 24-7. I guess I could try to force it to do it while logging. I know right now with the shield in the 95-96 degree weather my IAT are running around 106 degrees. Normal idle is like 700-800 rpms. Then after sitting in traffic for a while it will jump to 1000, then to 1250, then to 1500, then sometimes if it is a really bad traffic jam it might even get to around 1750. This is only on those occasions where I am sitting in heavy rush hour in Atlanta type traffic. So far in ST I have not seen a table that defines this threshold. Maybe in the new ST advanced that is on its way to my house! Supposedly there is access to more tables. What is the purpose of raising the idle? Is it to keep the same amount of air flowing through the engine or something?
Ok it has GOT to be the heat messing around with the ECU. I went from almost dying every time I came to a stop this morning at 75 degrees ambient to high idle of 1500 this afternoon at 103 degrees outside.
Ok one thing I noticed is that the Throttle position is not going back to 0 when this happens. Today when the idle was kicked up to 1250 rpms it was at a TPS of 2%. IAT is getting pretty hot...up to 150 degrees when sitting in 100 degree weather and the fan kicks on. It goes back down after I start moving and returns to like 106 in the same 100 degree weather.