I gotta a 91 240sx, im having problems. I hit some water one night, and now when ever i hold it at a constant RPM or idle it sounds like a v8 with big a cam. Would anyone have an idea on what would be causeing this. Would it just be my mass airflow sensor? or more? Thanks for your time and help..........

try pulling your plugs and cranking it a few times. You may see some water spit out of some of the cylinders. Also, examine the plugs to ensure none are fouled. MAF might be damaged and faulty too.

Check the TPS, dry the connector and also check your distributor and see if moisture got in there. Might need a hair dryer to dry things out if it's wet. Other than that, it could be a vacuum leak. As another check, when your maf goes bad, generally you can't rev the engine above 2000-2500 revs before it spits and sputters.

2nd on the dizzy cap. They're known to both; get moisture inside when cold water hits the hot cap..... and they're also known to crack allowing an arc path to the housing. The simple thing is to put a new dizzy cap on especially if it's old.

You can do a resistance check on the maf to see if it's working properly.

If it was real recent, you might have water in a connector causing it to short out. Just give it time to dry out.

The worst possibility is that you ingested water into the motor and partially hydrolocked it. A compression check might answer that since a cylinder with a bent rod would have lower compression.

Good Luck