420A P0505 Idle code keeps appearing

[Brian O Conner]

So I just got my car running after frying the ECM and Crank Shaft Positioning sensor. Put new ECM on and Crank Shaft Positioning sensor. Car starts idling weird and throttle response was delayed. It ran smooth other than idle going all over the place mainly higher like 2500.

When you hit the gas pedal there's a delay and it revs up slow. Like I said it didn't sound bad but takes a lot longer to rev up to 4000 rpm than it used to maybe 2 to 3 times slower than it did before.

I scanned the car and it showed code P0505 Idle control system code. I changed the IAC Valve and it did not fix the problem. I changed the Throttle Positioning sensor and that did not fix the problem. I know that the CPS, Crankshaft Positioning sensor, TPS sensor, VSS and Map sensor was on the same ECM ground transistor I fried on ECM.

I am just wondering if it damaged the MAP sensor?

 

[Brian O Conner]

Changed MAP sensor wasn't that.

 

[VelocitàPaola]

Any damage to the wires going to the IAC? If you measure the resistance across the two coils inside the IAC motor at the PCM connector, is it within spec? Any vacuum leaks?

 

[Brian O Conner]

Any damage to the wires going to the IAC? If you measure the resistance across the two coils inside the IAC motor at the PCM connector, is it within spec? Any vacuum leaks?

Do you got any diagrans I see 4 wires

 

[VelocitàPaola]

I don't have any diagrams on hand, but the four wires are correct. The motor is made of two separate coils, so there are two wires for each. I could be totally off, but I believe they normally measure around 50 ohms. Can you track down a factory service manual?

 

[Brian O Conner]

I just cracked the P0505 idle mystery that people have been fighting since the early 2000s. I am not getting any spark to cylinder 1 or 4 at all and its not the coil pack because I put a different one on. I guess if your cylinders arent firing right you will get a P0505 code. I am still in process of whats causing the firing problem but at least people now know that tps,iac valve and Map Sensor arent the only things that can cause this problem.

 

[Brian O Conner]

I ended up fixing the problem it ended up being the wrong ECM I traced the wires continuity from the coil pack connecter to the last inch of ecm and that was the problem. I got the right ECM and car is running amazing I did a l test drive and even did some burnouts after I changed the oil again. I actually believe the first ECM they sent me was for an automatic. Mystery Solved.