Curious what could be causing random rich spikes. Stock Twins, open exhaust, AEM Stealth 340 fuel pump, Adaptronic Modular PNP. Fuel injectors are stock. Could this simply be an injector issue? It is random and only seems to happen under relatively steady cruising throttle. It is enough that I feel it though.

 

What are your sensors reading and are your transients being activated? Also, I'm from Eugene! Glad to see another Oregonian on here!

 

Vacuum, fuel pressure, injector duty and TPS are all pretty consistent when I get my spike. Not sure how to check transients. I haven't gotten into tuning transient conditions yet.

 

It will likely be TPS noise causing a false trigger of the async injection.

 

Are the injectors being commanded any differently during spike?( calculations trace page under diagnostics will also help with this, in addition the logs etc) If so you will have to look at why If not, then this can just indicate a slight misfire too.

 

I have the exact same issue with my modular ECU. Cruising on the freeway ~3000-3500 RPM the engine will randomly drop out and jolt the car, almost as if the engine quits for a fraction of a second and then comes back to life. I had the laptop hooked up last time and noticed a similar rich spike in the AFR signal just like you're experiencing. The car doesn't behave this way any other time. @Turblown what would cause a misfire only in cruise? I would expect a misfire to be more prevalent during acceleration/high load.

 

Post the ALG log file.

 

I believe I found the issue. Looks like the internal MAP sensor might be failing. Under steady cruise the MAP signal will randomly jump from 45-50 kPa up to 100 Kpa. In response the injector duty cycle doubles and the ignition timing retards a few degrees. Guess it's time to buy a GM 3-bar map sensor. I couldn't get the .alg to upload for some reason but the .csv version of the log should be attached. This same instance happens again around the 540 second mark as well as the 625 mark.

 

There was a recent 3rd revision on the IMAP design BTW, so fingers crossed it won't be an issue for others. I agree with your finding, and solution.

 

I am having similar issue, is there a way to replace IMAP ? Keep us posted on the 3rd revision!