while fixing my intake today, i accidently started the car up with just the accordion part on/..i shut it off right away, and i finished the job up....i start the car, and me CEL comes on....i check it...oi get 0102 (mass air sensor) and 0304 (knock sensor) .....im gonna reset the ECU in am inute, but are those codes mostly because i started the car with it on? should i worry about anything.....i hope the light doesnt come back on....but someone le tme know plz...kthx

 

ok also, i noticed a silly detail, but the light for me says SERVICE ENGINE SOON ...not check engine
1 more thing, when im coming to a stop, my needle on the tach will drop to about 200 rpm, then jump back up to 500-600....its also a litte rough sometimes...nothing too bad.....anyone know what the problem could be?

 

It's normal for the Mass Air Sensor code to trip if you run the engine without the MAF properly installed. It's probably safe to assume the knock sensor code is also related.

For the idle thing, you may want to try cleaning your throttle body. If that doesn't solve the problem, adjust your idle up to around 700 rpm.

Btw, do you know where you should have posted that question?