milage reading wrong? need help asap

[Freshman6969]

alright im in need of a bit of help ASAP if possible

heres a little back drop....

Back Drop-

the car is an 2001 chrysler pt cruiser, my mom bought it brand new, the car has APPROX. 26500 miles (ill get to this in a minite) it sat all together for about 6-7 years with my mom only starting it rarely, then she started driving it every day (less then a mile each day) last year during the summer, before that we had it sit, then shed drive to the store or something then straight back home, so it was rarely driven except for when she first got it, it was jump started a pretty good amount, which is why i think somethings fucked, anyway on to my problems....

Problems-

i drive 30 miles to work everyday, roughly, my odometer says i drive 5 miles or so, so i know my odometers off right now, im prob around 26500-27000 by now

also i seem to be using alot of gas in a short amount of time, i have to fill up every 2.5 days, so 60+60+30=150 miles, and its a 15 gallon tank ( i learned its never topped off so lets say 14 gallons to be my max) so 150/14=10 miles to the gallon (now thats ROUGH, but thats still low, like really low

even with my box/batts/amp and woofers, i shouldent be getting about 10mpg, i know some guy in LA that gets 23 with a 2 18's wall and 5 group 31 batts, with no upgrades to anything to raise his mpg

lastly, when ever im over 15mph, and i have my blinker on it dings, its not intermitent, it ALWAYS happens, it happend when my mom actully started driving the car everyday during last summer, so since ive been driving it its been doing it, and you can only imigine how annyoing it is, but i learned i cant cut the dinger out, seeing as its for my headlights, seatbelt, etc

Current situation-

i just installed a new PCM about an hour ago, so im not 100% sure if that fixed it or not, i figured i fried something in the PCM to fuck with my milage and my gas and all that nonsense, ill know in the morning weather or not either of those are fixed

now, what im asking from you guys if you can help me is do you have any other suggustions/opinions/things to check/ trouble shoots etc that id be able to do if this isent the problem, i spent 160$ on a new pcm which is alot for me right now, but this is my daily and i need to get to and from work with decent gas milage, and to get rid of that fucking dinging every time i turn

sorry for the read but all the info is needed, if you guys need any other info let me know

thanks!

[bass_stalker]

ok first of all the guy you know in la is an asshat and is probobly lying about his mileage, two have you checked the plugs and or coils/ plugwires, i dont know if the battery being dead constantly may have fucked something up with your computer

[Freshman6969]

Its not the pcm, just got to work says I drove 4.3 miles yet I drove 30 im clueless here

[Jessica]

Try this;

Calibrate Speedometer and Tachometer. Press and hold odometer trip button then switch the ignition from lock (Off) to unlock (Run). Hold trip button for 5 seconds then release. The cluster will then step through several displays for function verification.

Edited May 19, 2012 by strangeduck

[Freshman6969]

Ive done that a few times and its good across the board, ill do it again tho to make sure

[Jessica]

And as for your dinging read the first post here, seems fixing a ground wire in the door helped this guy. Did you have your door panels off at some time? If you did you may have accidentally loosened the ground somehow.

http://repairpal.com/chrysler-pt_cruiser-2001

[Jessica]

Well, i havent found too many people with your issue, but all i can find is it may be a speed sensor, i think you vehicle has more than one, or the TCM. Have you had it put on a diagnostic machine yet?

[95legwagon]

any check engine light or flashing lights?