I tried to go for a drive yesterday and discovered the engine won't run properly. My engine has been running well up to then and I was really surprised to have this problem. Would you please help me work through this?

So basically, I can get the engine started and it'll warm up at idle OK. The engine dies when I apply or remove throttle at anything but very gentle rates. I'm getting AFR readings all over the place and I first thought my Innovate LC2 O2 was causing the problem. I rewired the LC2 on Saturday so it was directly connected to the battery via a relay because I'd been having problems getting consistent readings from it. Then yesterday I tried driving the car for the first time and had this trouble, which made me think the O2 sensor was continuing to malfunction.

But today, I turned off EGO correction to take the O2 sensor out of the loop. The LC2 appeared to generate correct AFR readings but the engine still won't run. To confirm, I removed power to the LC2 by disabling the switch line to the relay. I briefly ran the engine like this while seeing the same results. That implies to me that the problem lies elsewhere.

Any ideas what's going on? I've uploaded my tune and a log file to see if anything looks off.

 

I've done a little more research and I believe I've got a vacuum leak. My boost gauge isn't showing as much vacuum as it should and the engine is running rougher than it should. That's obviously not a problem with the Megasquirt or the O2 sensor and I'll need to go in another direction. I couldn't find the leak with a quick once over so I'll take a closer look tomorrow.

 

I didn't get a chance to take a look at your log (just FYI). But it soundsl ike your MAP sensor could not reading from your vacuum source. Are you sure that the signal line is plugged in? That would explain why it went from running to not so suddenly.

 

Good call. The line to the MAP sensor was plugged in but got kinked as a side effect of my wiring work. Everything works great now that everything is straightened out. Thanks much for the suggestion.