1996 cobra dies at idle.

Goliath85

New Member
Aug 28, 2018
4
0
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Indiana
Ok guys I've been searching the forums and haven't really found anything that completely matches the issue I'm having. I recently purchased a 1996 Cobra. Has around 120k on it. Car is super clean. The previous owner has done a lot of mods to the suspension but only a few performance. It has the JLT intake that runs down into the front wheel well, a Bama tuner and off road h-pipe. That really seems to be it. So onto the problem. When cold the car runs and drives fine, but after it's warmed up the car will just die at idle. When you come to a stop the idle will fluctuate a little bit then dip low and just die like you turned the key off. If you keep the RPM's up just a little it will stay running and it has plenty of power driving. I've removed the tune and put it back to stock. I check the MAF and it looks brand new and the air filter is new. Fuel pressure is fine and it's not losing any before it dies. But it is literally like you just shut the key off. Any suggestions?
 
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wmburns

SN Certified Technician
Aug 14, 2009
5,849
505
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Houston Texas
Do you have access to an advanced ODB2 scanner? If so, this could make short work of this problem.

Here's some information on an affordable Windows based unit.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

My recommendation is to start with a through review of the car's charging system. If you believe that your problem couldn't possibly be battery related then the battle has already been lost.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Is the fuel pressure regulator intake vacuum reference line connected and LEAK free? Have you measured the fuel pressure?

It would be handy to know what the PCM "thinks" the value of:
  • MAF flow
  • Input air temperature (IAT)
  • Engine coolant temperature (ECT).
  • IAC duty percent when cold, warm, and hot at idle and part throttle.
  • TP-mode (CT, P/T, WOT)
Note, a vacuum leak can "cause" the MAF value to read too low and also cause the reported symptom.

Here's some more information on how to trouble shoot an idle/IAC issue.

Troubleshoot IAC idle problems 1996-2004
https://www.stangnet.com/mustang-forums/resources/troubleshoot-iac-idle-problems-1996-2004.13/