High idle problem.

[jordanxmiles]

I wasn't sure where to post this since I have an MP3, but I figured it would be more likely to get noticed in the MSP section.

I installed a new clutch and 7lb. Fidanza flywheel last week and have been having trouble with a high idle every since. My car idles around 1400 to 1700rpm when my foot is off the clutch pedal, and when I press the clutch pedal in it dips down and stays at normal idle of 750rpm.

Has anyone else experienced this? I've searched the forums for the past week and can't find anything similar. I'm thinking the lighter weight flywheel is allowing the engine to idle higher. Does that make sense at all? Or should I check for other things like a vacuum leak?

 

[dirtysouth_msp]

It's not likely due to the flywheel. I've been running the Spec flywheel which is almost the exact same for several years now without issue. What clutch are you using?

 

[bschatz2]

Do you have a CEL? I had this problem with CEL code p0850 and was fixed by replacing the neutral safety switch. I too have a Fidanza with a stage 1 Exedy clutch.

 

[jordanxmiles]

Wow, I just noticed that you guys replied to this. Still having the same issue. I do have a CEL, but I forgot to write down the code. Where is this neutral safety switch located?
And I'm using a stage 1 Spec clutch.

 

[bschatz2]

The neutral safety switch is under the transmission towards the back of the car, check out this PDF on page 3 to see where it is specifically:
http://www.mazdaspd.com/resources/Transmission_Rebuild.pdf

When I had this problem, my car would idle around 1500 to 2000 rpm before I would step on the clutch and have it go back to normal.

 

[jordanxmiles]

Thanks, this looks like it will solve the problem since that switch did get a little banged up during the install. Do you happen to have a part number for it?

 

[jordanxmiles]

Just checked on the codes and they are P0705 and P0507. Any ideas on those?

 

[bschatz2]

p0705- neutral switch input circuit malfunction (MTX)
P0507- Idle control system RPM higher than expected

Those are the descriptions that are given by the workshop manual (http://www.mazdaspd.com/manual_files/01-02B.pdf)
They still both sound like they can have something to do with the neutral safety switch as your problem sounds identical to mine. Whats interesting is that the code my car threw wasn't even in the workshop manual.. lol
If you wanna try replacing the neutral safety switch, its part number is G562-17-640

 

[jordanxmiles]

Thank you so much for the help bschatz. I'm heading to the stealership now to pick up the part. I'll let you know how it goes.

 

[bschatz2]

Hey no prob man, just make sure when you're replacing it, you get the switch in fast. You don't want all your tranny fluid pouring out on you.. LOL

 

[jordanxmiles]

Ordered the switch and replaced it yesterday. Car idles perfectly normal and better than ever. I am still getting the P0705 code though. From all the threads I've read it seems like everyone has problems with it coming back after they've replaced the switch, but no one really knows why.

 

[bschatz2]

That sounds normal with the code still appearing. After I got my idle working perfectly, it took about 10 times turning the car on to cycle the CEL code out.

 

[hornsfan10609]

Resetting the ECU should erase the code.

 

[blazinrola80]

yes i experienced same thing.. buddy that helped me pinched the wire.. from the sensor.. smh luckily it was a tranny swap.. had old sensor

 

[jordanxmiles]

So I got pulled over last night because my reverse lights are staying on now through every gear. I just replaced the reverse light switch when I did the neutral safety. Bad switch maybe?