My 91 Mustang has been doing this for quite sometime and I'm not really sure if it's a problem or not or something typical with adding a crank underdrive pulley on, but My Voltage at idle with nothing on varies from 13.0v-13.8v.i have what appears to be a 130 Amp Alt since the whole thing is incased unlike the 75amp with the fan on the outside. Anyway, when I'm driving or when the head lights and fog lights are on...after driving for a bit and then stopping at a stop light for instance...the voltage drops to around 11.9v-12.0v minimum. I know this probably isn't good and is probably caused from having just a crank underdrive pulley. I have a brand new crank pulley. I'm just seeing what people think first before changing it or if it could be solved without reverting back to the stock crank pulley.
Second issue.....When I turn my car on, the rpms shoot up to around 1500 rpms and drops down to 1200rpms and idles like that for a minute or so, then slowly drops to around 800-900rpms. Is this normal? I do not have my EGR crap hooked up and the two spot where the hoses would go on the spacer are not hooked up and are not covered. Is this causing a vacuum leak-like effect on the engine? or do I have a leak somewhere else or other problems? I'm also experiencing an issue with my car almost dying when I get caught in neutral when changing from lets say...Reverse to Drive (vice versa). The idle in neutral is around 1200rpm....I doubt that is right at all! Because if I'm driving and I put it in neutral while driving it should go to the base idle of around 800 rpms and not 1200rpms right? I think maybe these two issues is what is possibly causing my brakes to be much weaker than they should be. (Had another thread on brakes before)
Second issue.....When I turn my car on, the rpms shoot up to around 1500 rpms and drops down to 1200rpms and idles like that for a minute or so, then slowly drops to around 800-900rpms. Is this normal? I do not have my EGR crap hooked up and the two spot where the hoses would go on the spacer are not hooked up and are not covered. Is this causing a vacuum leak-like effect on the engine? or do I have a leak somewhere else or other problems? I'm also experiencing an issue with my car almost dying when I get caught in neutral when changing from lets say...Reverse to Drive (vice versa). The idle in neutral is around 1200rpm....I doubt that is right at all! Because if I'm driving and I put it in neutral while driving it should go to the base idle of around 800 rpms and not 1200rpms right? I think maybe these two issues is what is possibly causing my brakes to be much weaker than they should be. (Had another thread on brakes before)