Hello all

I have a 2003 Mach 1 that stalls when AC is turned on when the car reaches its normal temperature. IAC, MAF & TB have been cleaned also checked for leaks and all clear. I have also changed the O2 sensors upstream. The Mach also stalls at times in stop/red lights AC off.

After the built the Mach would stall here and there while slowing down or complete stops obviously needing a tune. RPM’s at idle would be around 8-9 roughly, now just before the tune my brother swap the battery and connected it backwards for a good 2 seconds. Lighter and stereo fuse are the only fuses that blew but the Mach didn’t feel the same. At idle it would now be at 5-6, it would struggle more to stay on. I got the tune done but the stalling is still there I feel it stalls even more after the battery incident.

Modifications
Engine built .30 over
Camm work
MAF 90
42lbs injectors
CAI JLT
Off X pipe
Chipped and tuned

 

If it were me, I would look first at all of the vacuum lines...if they are like my Cobra, there are allot of them, and allot of them are tucked way in the back. You have a bit of a high idle, and that may be a give-a-way, as well.

The other place to look is with your fuel pump. Our '98 would stall coming to a stop, or turning left, and sometimes when the A/C compressor came on.

If you get good pulls all the time, these suggestions are probably wrong.

 

I've got an 03 MACH 1 (auto) doing the SAME EXACT thing as Alfred's was in the original post... Did you get it fixed, and please let me know what the problem was?!?... The irony is mine had an alternator that was putting out 20V!!!... So after fixing (replacing) that I'm having to deal with this, and you mentioned a battery issue in your post so figured our issue is the same... Afraid a sensor got ROASTED (no OBDII codes)... I'm plenty advanced into all this so speak your mind, I find it odd from my experience because it runs GREAT!!!... Totally stock, no mods, no tune...

Thanks crew, and HOTROD hard... NEVER give up, and DO NOT EVER let anyone discourage you... Too many people doing it now-a-days...

Much appreciated,

Mark
highplace11

 

Welcome,

It's Been Five Years Since The Op Has Been in But Some Have Came Back after That Long. I Will Do a Mention and See!
@Mach1Alfred

KC

Meanwhile Look at The No Dtc Pdf in Here!

https://themustangsource.com/forums/...ncerns-550469/

 

I know and a one post only... I just discovered your forum after searching on this issue and am HAPPY to be a part of it... I PMed' him also... Figured it might be a sensor that doesn't take kindly to being drilled by bad 20v alternator or a backwards polarity battery... hahaha...

Thank you KC!!!...

Mark
highplace11

 

We Try To Be Upbeat as We Can in Here! Almost Pulled The Trigger on a Mach 1 When The 05's Seemed To Be in Limbo! Still Would Love To Have One Really Got Attached To The Body Style After Doing Some Overhaul Work on The Sn95 Forum!

https://themustangsource.com/forums/f650/

You Should Do a Post in Introductions and Post Some Pics of Your Stangs!

KC