I have a 98 GSR with what I believe is a 94 block and a 96 head, 95 ECU (yeah I know, fckin frankenstein car... got ripped off but that's another story) So anyway, when I'm in neutral and I rev it to just over 1k rpm, I hear a weird sound that sounds kinda like scraping metal... it goes away when I let off a little or gas a little, but when I take it up to 2k it does the same thing except slightly faster. It does it at other RPMs too but those are the only two I took note of. when I had my friend try to listen to where it was coming from, he listened to all over my engine bay but it was loudest near the wheels, both of them. I can't figure out wth it is... could it be my rotors just vibrating or something?

The sound is like metal scraping, and isn't constant.. it's like scrape *wait* scrape *wait* etc... for the life of me I can't figure out what it is. maybe you guys have some better ideas?


Also, slightly off topic question but how can I tell if my ECU is chipped? I'm running really rich and have alot of black build up on mybumper after just like 2 weeks of more or less normal driving. Also, my gas mileage is starting to suck more and more... when I first got the car it seemed a little better, I dunno what could be causing it. now I get like 200-240 to a tank.. it's probably because i'm running rich, right? and if I am running rich, is it because of a chipped ECU, or bad tuning, or what? Should I get it retuned? It's stock except I have the intake box off and it's lowered. If I do need to get it retuned, how much does that usually run and does anyone know of any good tuners in the CA Bay area?

 

Heat shield or the "A" pipe (lower half of the header) is rattling. Very very common. Pull the ecu and look inside for a chip, thats the best way to tell. If its stock except for the intake box, then a stock ECU is best. Generally in city driving around 240 is avg (on 9.5-10 gallons of gas). I've gotten down around 180 on a tank with the right driving and temperatures.