Hi all,

After replacing my thermostat I went to clear all existing codes but I received a P0507-(Idle Air Control System Higher Than Expected - Engine Speed too high). I've been chasing around what I believe is a vacuum leak but I have zero idea where its is coming from. The RPM generally stays at 1750 but will drop down close to idle then will almost bog down and stall out. While I was replacing the thermostat I replaced the intake manifold due to cracking and I also replaced the PCV hose that comes out the back of the valve cover. The vacuum pump and HPFP are brand new and I have data logged both and they seem to be working just fine. Any input would be greatly appreciated.

Thanks,
Tyler
@r56_tyler ig

 

Have you checked the electrical connectors on the thermostat housing? From what I've read, these can be mixed up with one of the other 4 pin connectors. I didn't have that issue when I changed mine, but apparently, it happens.

 

Ill check a wiring diagram and confirm, thanks Scotty!

 

*UPDATE*

After further investigation I found a few things.

1. PCV hose had a crack when replaced I saw a drop in a few hundred RPM but still had the same code after clearing

2. Fuel tank purge valve hose also had a crack replaced and still had a the code after clearing

3. Main connecting port to throttle body was split in half replaced throttle body, cleared codes haven't returned since

Car ran fine for a few days never took it out received another code P0303 so now im on the hunt to find out the cause for this one

Here is the new thread I started for this misfire: https://www.northamericanmotoring.co...oss-p0303.html