check engine light and rough running

[titaniumdave]

I had the oddest thing happen today, went to get coffee with my wife in the NSX and the car was running fine. Came back to the car an hour later, it started fine, pulled away from the curb Ok and then I noticed the engine was a touch rough after driving a couple blocks. I drove a couple more blocks and the check engine light came on and the car seems to be missing a little bit. I pulled over, turned the car off and checked to see if a hose had come off or there was something leaking. I turned the car back on, the check engine light did not turn on but the car still seems a little rough. When I start from a full stop, I can almost feel the car not firing strongly on all cylinders(my imagination?). When I listen to the idle the right tip sounds different than the left, like there is a different rythmn, missing a beat.

I am running by-pass pipes because I am still trying to sort out my A/F ratio, I just welded a bung in the rear bank pipe. Other than that, and an oil change I have not done any thing to the car in 400+ miles.

Any thoughts or directions, I could not find anything quite like this in my search.

 

[nsxtasy]

It sounds like you haven't pulled the codes from the ECU yet. Follow the procedure in the Fuels section of the service manual (as well as the DIY section of the FAQ) to find the code(s). You can then use the service manual to determine the meaning of the code and the diagnostic procedure to follow.

 

[titaniumdave]

Code

Well the code was 1, front o2 sensor voltage. I cleaned the connectors, put some dielectric grease on the pins and put it all back together. Cleared the memory and started it back up. The car ran rough like before, died as I was trying to pull out of the driveway but I figured driving a couple more miles won't hurt anything. Went for a short cruise and the car kept running better all the time, by the time I got home it was idling smooth and the roughness was gone, including the strange rythmn from the right exhaust tip.

Did the car just 'learn' how to run right? Cool that it works again but I like to know why stuff works. Any thoughts?

 

[djjoonie]

.

 

[NSX-Racer]

Just a thought: If the ECU detects that's something is wrong it can change to a somewhat "emergency running mode" with fixed ignition and fuel settings. That may result in a rough engine behaviour. If you clean this error code the ECU can switch back to business as usual.

 

[titaniumdave]

learning

I talked with my local NSX tech and he said the car does indeed re-learn how to run, once the short term memory is erased. I like having a car that is a quicker study than I.