Woes of P0507 Idle Control System RPM: Higher than Expected

smetzger · Dec 3, 2014

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

rit14623 · Dec 3, 2014

Remove your EGR valve and clean out the carbon build-up on the inside of the valve.

The_big_dill · Dec 3, 2014

Sounds like a vacuum leak to me

smetzger · Dec 3, 2014

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 · Dec 4, 2014

Swap the IACs out and see if code follows it

smetzger · Dec 13, 2014

i12drivemyMP5 said:
Swap the IACs out and see if code follows it

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.

bigkert · Dec 14, 2014

Hey just check the tension on your accelerator cable and reference your idle speed! 700 + or - 50 rpm

takotruckin · Dec 14, 2014

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.

smetzger · Dec 14, 2014

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.

Is this the wire I should be disconnecting?

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.

The_big_dill · Dec 14, 2014

Go to a mechanic and ask them to use a smoke machine to check for vacuum leaks and set this problem behind you.

smetzger · Jan 23, 2015

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.

pcb · Jan 23, 2015

Here's the parameters they tell us about.

farqyj · Aug 20, 2015

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 · Nov 11, 2015

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.

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.

huckfinnstyle · Feb 9, 2017

I wrestled w/ this code and a couple others. My write-up is here

NaturalFlavored · Feb 9, 2017

Way to revive a dead thread.

i12drivemyMP5 · Feb 9, 2017

they're all over the place, how can you not?

pcb · Feb 9, 2017

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.

horseflesh · Feb 9, 2017

smetzger said:
I have a second '02 Protege (yup I am a masochist).

whew, glad to hear i am not the only one...

*good luck, keep us posted.*

ah.. 3 years after the fact. Still good information. Thx

Woes of P0507 Idle Control System RPM: Higher than Expected

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody

rit14623

The_big_dill

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody

i12drivemyMP5

<<<<<<< >>>>>>>

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody

bigkert

Member

takotruckin

Member

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody

The_big_dill

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody

pcb

The Diagram Dude

farqyj

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody

huckfinnstyle

Member

NaturalFlavored

i12drivemyMP5

<<<<<<< >>>>>>>

pcb

The Diagram Dude

horseflesh

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