Okay....so here's what's up. My prelude Vtec has been a great car but then last month the stereo began to cut out for long periods of time (my subs continued to run though) and eventually would come back on. Used to be just annoying, but now the stereo has been out for a couple weeks and its getting frusterating. That isn't even the weird part though. THe car doesn't stop running when I turn the key to off. The engine runs horribly when its in the off position, but STILL RUNS! The engine finally shuts off when I take the key out. Also when the key is in the of position the radio works perfectly. Anyone have any clue about what this could be or better yet how to fix it?? I'm pretty sure that the real problem has nothing to do with the stereo because I have gone over al my connections and haven't found anything abnormal. THanks. ~Bo

 

Well here are a few thoughts.... If the car is running after you turn it off it sounds like it could be one of 2 things.
1. The engine could be what's called dieseling. This is often caused by too low octane gas. Are you running 89 or higher? If you've been running 87 stop now and fill up with the highest octane at the pump. See if after a tank or two it stops. Other causes could be your spark plugs. Some plugs run hot and can actually get so hot they are able to ignite fuel even without a spark. Also if you have a lot of carbon buildup this also can retain a lot of heat and ignite fuel....

2. This is what I am kinda leaning towards because you say it stops once you pull the key. It could be your main relay. I'm not sure if there is an ignition relay in our cars. But I don't think so. Sometimes when the relay goes it can actually leak and cause the engine keep running. But this would stop once you pull the key out. This also is what I am thinking because it could cause the radio problems you are talking about.

So if you know anyone else with a VTEC see if they will let you try their main relay. See if that fixes the problems.

 

What is the main relay, where do I find it and how would I test it? Thanks a lot.

 

the main relay is under the dash on the left hand side. It's way up in there. Or at least that's where it is in mine. I don't know off hand how to test it but it should say in the helms. I don't have mine with me right now.