So up until recently, my car has always had the regular cold start with the Hyrda. I could start the car up and it would idle slightly higher and when the coolant temp reached a specific point, you could hear the idle drop down and get louder as the Hydra changed the map. Even when driving, you could feel it be a little more sluggish when cold and feel the cold to warm change over when driving. Well, a couple of weeks ago I was up on The Dragon and driving the car hard. At some point, I was running WOT and the car suddenly bogged down and lost power....it was kinda strange. Fearing something went very wrong, I pulled over. When I did, the car would idle very low/rough and stall. It was also very hard to start, almost like low compression. I let the car sit for like 30 min with the hood open to let everything cool down. Mind you, it was pretty cool that day and I had been driving with the heater on full blast and the car was NOT overheating or running warm by any means. So I got back in the car and it started right up and idles perfectly normal. Since then, I've noticed that when I start the car from cold, the idle is different....and if I let the car sit idling, there is NO change as the car warms up. Clearly it starts up running the "I'm already warm" map/setting.

So, I don't even know where to look. I did re-load a map but it made no difference. With the laptop hooked up, I see what looks like normal readings from the temp gauge. I unplugged the temp sensor that is on the back of the head and RPMs shot up, indicating the ECU was not happy about this, then plugged it back in an all was normal. I have no idea where/what to look for at this point. While starting/driving when cold is fine, I don't like when things aren't acting like they're supposed to.

Halps?

 

Alrighty, after disconnecting the battery and re-loading the map, cold-start idle has returned. WTF? Oh well.

 

My first two thoughts would be maybe you've got a failing coil pack, or maybe your Hydra's 5V rail is getting weird. Some of the early ones had that issue, and both could cause something similar.