Throwing maf sensor code also 404 and 405 performance codes

IO74US

MEMBER
2003 PONTIAC MONTANA
3.4L
6 CYL
FWD
AUTOMATIC
134,000 MILES

All sensors have bee tested and all are good.I believe pcm is bad but not showing code for pcm problems. Testing egr valve and pin connector at egr. QUESTION I HAVE. Red wire at egr pin connector which supplies 12volts test with connectr (disconnected is 12 voltes) with connector installed on egr the (voltage is.005) Voltage is supplied to red wire comes from the pcm #20 pin. If there is no dead short in supply wire (red wire) I should have 12volts at red wire with pin connector installed on egr or connector open from from egr WITH IGNITON SWITCH IN ON POSITION ENGINE NOT RUNNING? AM I CORRECT? No one will answer this question CAN YOU I believe pcm is bad. SYMPTOMS ARE let off accelerator engine would shut off///////now engine running at 2100 rpm"s at all times with no service engine light on PLEASE HELP I AM LEANING TOWARDS NEW PCM///////CANT AFFORD PCM THEN EXPENSE FOR DEALERSHIP FLASHING OF PCM

1 Reply

HMAC300

MECHANIC
48,601 POSTS

First thing for rpm problem is to clean throttle plate on both sides and iac hole with choke cleaner. If ther eis no service engine light why are you saying it's a 404 and 405 code that may be a stored code that has been repaired. Those two codes deal with egr valve partially open which may have had carbon in it keeping it that way. Evidently it cleared up as engine light is not on so don't worry about it. Also check for a vacuum leak. For high rpm like hoses off, cracked, broken etc.