Should a Mustang Mass Air check engine light flash on while driving

[rjrobin2002]

My Mustang Mass Air does not have any KOEO and KOER codes other than a few emissions codes from no EGR when I connect the diagnostic system. My Bronco has a random stumble while driving and the check engine light will come on while it's driving even though I don't have the diagnostic ports connected.

Should the check engine light come on without the diagnostic ports connected?

 

[surfer-b]

Sounds like you have a short to the complete system or the PCM anyway

 

[Viperwolf1]

It depends on how you deleted the EGR. If you didn't modify the EGR valve position circuit you will get a CEL.

 

[rjrobin2002]

I was thinking short also. It's starts sputtering and the check engine light comes on and will turn off on its own. I thought the light just gave you codes when you connected the diagnostic ports on the OBD 1 stuff.

 

[Timmy390]

Soft codes and hard codes. Soft codes will clear once the condition no longer exists. Hard codes are stored hand have to be cleared with a scanner.

I had Garry do my ECU and no lights or codes.

Tim

 

[Viperwolf1]

I was thinking short also. It's starts sputtering and the check engine light comes on and will turn off on its own. I thought the light just gave you codes when you connected the diagnostic ports on the OBD 1 stuff.

It's multifunctional. It's a warning light and a diagnostic indicator.

 

[rjrobin2002]

It's dying at Red lights now, I am gonna get some fresh codes check fuel pressure and a cyl balance test when I get home.

 

[Timmy390]

Do you have VSS hooked up?

Some get away with not running it. I didn't take any chances and hooked it up

Tim

 

[rjrobin2002]

Checked codes and
KOEO -81, 82, 85, 84

KOER 94, 44, 33

CYL balance test passed, I could not find my fuel pressure guage.

I am stumped cause with its check engine light coming on every other mile and it running so bad on the way home, you would think I would have some significant codes other than these non important emissions codes from me not running EGR.

 

[rjrobin2002]

No VSS, this harness, and computer ran fine on a previous Bronco with no VSS for 10,000 miles.

 

[Viperwolf1]

Checked codes and
KOEO -81, 82, 85, 84

KOER 94, 44, 33

CYL balance test passed, I could not find my fuel pressure guage.

I am stumped cause with its check engine light coming on every other mile and it running so bad on the way home, you would think I would have some significant codes other than these non important emissions codes from me not running EGR.

OBD1 has no means to monitor fuel pressure. Therefore, low pressure will not cause the CEL to illuminate. The same is true for ignition problems. You need to actively troubleshoot those systems.

If the light is illuminating you should get a code into the computer memory. Those will flash after the KOEO codes.

 

[rjrobin2002]

I got 94, 44, 33 after KOEO.