[tru5o4bigtymer]

hi guys im new here i have a 2002 mustang 3.8l. i have been trying to figure out my problem i have had since december '08 when im driving and i hit the brake to slow down engine surges from about 600-1000 rpms and make a surging noise. then when i come to a complete stop the idle seems to be little lower then normal. no check engine light has come on at all. sometimes when i brake and come to a complete stop close to about 500 rpms and almost feels like it could die on me any help on what the problem could be i want to get the problem fixed but i dont know the source of the problem any help will be grealty appreciated!!!!!!!!!!!!

[Big Daddy's Stang>]

Welcome buddy, your prob could be your maf sensor I also have that problem but on mines the idle goes high, The maf is connected to your cai, also check if its loose or dirty and clean it....

[tru5o4bigtymer]

Originally Posted by Big Daddy's Stang>

Welcome buddy, your prob could be your maf sensor I also have that problem but on mines the idle goes high, The maf is connected to your cai, also check if its loose or dirty and clean it....

what can i use to clean the mass air flow sensor with? i know its a sensitve part i wanna be sure i dont damage it thanks

[shinerstang]

Computer contact cleaner or electronic parts cleaner. If it is not your mass air, we need to dig deeper into it......

[Big Daddy's Stang>]

You can get one of those already told at autozone...

[tru5o4bigtymer]

ok well im back with no luck i bought sum mass air flow sensor cleaner and sprayed and while i had it off i got a cold air intake and put it on....it still does it once it gets to just under 1000 rpms it surges like i say about 300rpms you can hear the engine surge and you can look at the meter and see it as im braking but once i come to a complete stop its fine. there has been no check engine light on at all. does any one think its the alternator causeing it? cause now i notice if i put my head lights at night it seems to get louder almost like a hum same way if i have my heater on or air. anyone one could fill me in im really clue less..if anyone can help thanks

[232-K7]

Originally Posted by tru5o4bigtymer

ok well im back with no luck i bought sum mass air flow sensor cleaner and sprayed and while i had it off i got a cold air intake and put it on....it still does it once it gets to just under 1000 rpms it surges like i say about 300rpms you can hear the engine surge and you can look at the meter and see it as im braking but once i come to a complete stop its fine. there has been no check engine light on at all. does any one think its the alternator causeing it? cause now i notice if i put my head lights at night it seems to get louder almost like a hum same way if i have my heater on or air. anyone one could fill me in im really clue less..if anyone can help thanks

do you mean 3,000 rpms?
or do you mean it drops to 300rpms and then bounces back up?

have you checked for vacuum leaks yet?

[tru5o4bigtymer]

my idle is 700 rpms so when im braking to slow down once it gets to just under 900 rpms on my gauage it starts to surge when i my rpms is about 700 almost idle and it goes up close to 1000 rpms on my gauge so the surge is about 300 rpms its not a big spike it started doing it in the middle of december but there is no check engine light so i dont know how serious of a problem it is i dont want it to cause any other problems you know that why i coming on hear to see if anyone knows the problem of could lead me in the right direction....how do you check for vaccum leaks im just a novice when it come to this car stuff im just learning

[ar0wan]

I'm going to assume you're in a manual and that when you come to a stop you disengage the clutch. The values you are describing as a 'surge' are pretty insignificant and could be totally explained by the load variance. I wouldn't sweat it if it's not dying or hitting peaks over 1700 - 2000 rpms.. I'm gonna do a seafoam this week, if this is a new problem for you have you considered that?

[tru5o4bigtymer]

i have automatic transmission actually...it started back in december doing this i really dont know what the problem is unless i take it to some autoshop. i really didnt want to pay alot to take it some where and for them to say they fixed it and the problem is still there. unless i record a video from my cell phone and try to post it maybe someone will see what i am talking about