Car stalls when moving a short distance in 1st or reverse and stopping.

tykempster · Mar 25, 2014

I did a HCI swap a few months back, along with headers and a new throttle body. Car runs great when I want to go more than a few feet. The only thing is if I reverse or move forward just a short distance and then stop, the car stalls out sometimes. It will start right up after that, but if I don't give it gas it will just stall again immediately after starting up at a normal RPM, then it just declines until stall.

No pattern that I can discern, sometimes I can reverse and it'll hold the RPMs rock steady, sometimes it'll dip a bit then recover, sometimes (maybe 25%) it stalls. Not a rough or jerky stall, RPMs just keep going down until it quits running.

MustangChris · Mar 26, 2014

vacuum leak, dirty MAF (unplugged MAF), bad ground (battery, CCRM).... that's where i'd start!

tykempster · Mar 27, 2014

MAF is clean and plugged in, everything seems tight and can't find a vacuum leak. I opened the IAC up about 1/4 turn more and it hasn't done it again...yet! Gonna go on my first long drive today since doing the HCI, throttle body, and headers. 400 miles should let me know if there's any problems I'd hope!

JerZeyStangz · Mar 27, 2014

If the IAC is old, that could be it. I had a similar problem back in the day every time I would reset the cars computer. I would put it in reverse it would stall, I would put it in drive (auto) it would stall. Only way it wouldn't stall if I started the car on a cold start and not let it warm up. After about 30mins of driving the computer learns how to idle in drive, and reverse then it never stalls again. Only conclusion I can think of is its bad IAC. I have had idle surge but never fixed it. If the car is warmed up and its idling after a long drive it starts to surge a few hundred rpms like someone is playing with the throttle cable. Is your car a 96+? This also happened to my best friends mustang which is 96 as well.

SNorange94 · Mar 29, 2014

My car has the same issue, also has hanging idle between shifts. It's pretty annoying.
Things I've done with no change are, CTS, plugs/wires, cap/rotor, PCV, air/fuel filter, and cleaned the MAF.
I also checked all vacuum lines and seafoamed the oil, gas, and through the intake.
I hope my list helps you narrow down your problem.

tykempster · Mar 29, 2014

I've actually done all of those. It hasn't died since I opened the IAC a hair. If your rpms are hanging between shifts that is for sure vacuum or IAC.