Woes of P0507 Idle Control System RPM: Higher than Expected

S

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody
New to me P5. 131k miles.

1) CEL came on with a P0507.
- replaced PVC, spark plugs
- cleared codes

2) P0507 came back with as a 'Pending' code
- Cleaned Throttle body (quite dirty on 'back' side)
- checked for vacuum leaks (non found)
- IAC valve resistance measured as 9 ohms (within spec of 7.7 - 9.3 ohms, but this was at 50F instead of 73F)
3) Pending P0507 goes away - thought problem was fixed.
4) 350 miles later get a CEL with a p0507

Any ideas? Timing belt is quite worn and tired looking and I am getting it replaced.

Thanks,
Scott
 
I suppose it's possible it is the EGR, but according to the shop manual that isn't one of the causes of a 507.

I did spray carb cleaner all over the different vacuum hoses and couldn't find any leaks.
Just dropped off the car at the shop to get the timing belt done, maybe I'll ask them to look for vacuum leaks.

If they can't find any leaks I'll take a look at the EGR valve.

If that doesn't fix it I'll start throwing parts at it. I have a second '02 Protege (yup I am a masochist), so I'll start swapping parts between the two.
 
i12drivemyMP5 said:
Swap the IACs out and see if code follows it
Click to expand...

Aarg... swapped throttle body and IACs (btw this was a real pain as the other TB gasket was like melted plastic), cleared codes.
Code came back despite swapped throttle body and IAC.

shop manual also lists..
1) accelerator free play as a possible problem. 1-3mm should be the free play.
How the heck are you supposed to measure free play of that small an amount?

2) actuator cable free play.
But there are no instructions for this.
Anyone know where this is and what the free play is supposed to be?

3) vacuum hose connections - already checked this.
 
It could also be a bad power steering pressure switch. Try disconnecting the single wire switch on the pump and see if the idle drops.
 
takotruckin said:
It could also be a bad power steering pressure switch. Try disconnecting the single wire switch on the pump and see if the idle drops.
Click to expand...

Is this the wire I should be disconnecting?
IMG_2043.JPG


I pulled it and it did not change my idle. I am idling at 850rpm once warmed up.

I also, tried adjusting the tension on the accelerator cable. It would only turn one way, towards the back of the car. This also did not change the idle.
 
Ok, so finally got this solved.
It was the IAC valve.

That's right I swapped TB and IAC with my other car and the code stayed with this one.
Took it to shop and they replaced the IAC and that solved the problem.

I have no idea how that is possible. The ECU's OBDII tests must have very tight parameters.
 
I keep having this one pop up too, and now I know why: for some reason my accelerator is sticking, and while I am stopped at a light, it tends to hover around 2000 rpm. Even if I stay on the brake and let out the clutch a little to lower the rpm, when I press the clutch back in, the RPM goes back up to around 2000.
Ha, now that I sit and type it out, it sounds like an obvious vacuum leak! I guess I have some checking to do.

BTW, I would like to thank all the contributors on this forum. I have been reading this forum for about a month, and there is an amazing wealth of information here.
 
smetzger said:
Ok, so finally got this solved.
It was the IAC valve.

That's right I swapped TB and IAC with my other car and the code stayed with this one.
Took it to shop and they replaced the IAC and that solved the problem.

I have no idea how that is possible. The ECU's OBDII tests must have very tight parameters.
Click to expand...

Code came back when temp dropped.

Good news, I believe it is now fixed.
I replaced the battery and idle is noticeably lower and code has not come back.
 
Old thread but still a relevant issue.

He had code P0704 for the clutch switch along with the idle code though... The ECU needs to know when the clutch is in or it's in neutral to send control to the IAC.

Troubleshooting a P0507 code by itself is a bit more challenging.
 
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