Idle fluctuation?
 

So today I replaced my clutch slave cylinder and clutch master cylinder. I took off the UIM to get to the slave and also cleaned my throttle body while it was off. After putting everything back together my clutch was fine and car started normally it also idles fine. But one problem as soon as I put the car in gear with the clutch down the idle bounces from almost exactly 1000rpm to 1500rpm and keeps bouncing until I either drive or take it out of gear. It drives in all gears fine and idles out of gear fine until I put it in gear with the clutch down, which is when it fluctuates from 1k-1500rpm.
I was thinking it could be a problem with my throttle body but reading up on here i'm also hearing it could be the neutral safety switch? I've never had this problem until now. Could it be that the switch is dirty from when I was replacing the slave? I know the neutral safety switch is around the same area of the transmission as the slave. Should I try cleaning it or replace it? It's weird that the idle fluctuations are almost exactly going from 1k to 1.5k though. :dunno:

Did u bleed both the slave and the master rite? Because it could be that the clutch is somewhat engaging so it makes the clutch touch the plate and make it act up

If it's a fairly precise idle bounce, then yes, it sounds like the neutral switch. One way to know for sure is to do an OBD2 code check for pending codes. It will take 3-ish drive cycles before you will get a lit CEL for the neutral switch.

Considering that you have to remove the clutch pedal to replace the clutch master, and to remove the clutch pedal you have to disconnect a switch on the clutch pedal that is in the neutral switch circuit...

...are you sure you plugged that switch's electrical connector back in? :)

The neutral switch itself is below the shifter, inside the transmission turret, so unless you disconnected that wiring, you probably didn't do anything that affected it there.

I bled both the master and slave pretty well I believe. Until just fluid comes out and no air bubbles. The pedal has pressure like it did before.

Yeah the idle bounce is really precise almost rhythmic. I don't believe I got that far in the transmission to touch or even see the neutral safety switch so your probably right. Ill double check the connectors on the clutch pedal and scan for codes as soon as I get my OBD scanner back from a friend I lent it to. Thanks.

I've forgotten to re-connect it a few times after re-installing my clutch pedal :)

I checked the connections and they look fine. although the one to the left that needs to be turned to remove. I'm not too sure if thats the exact position it was in before. I'm kinda stumped. I'm gonna try to maybe clean them tomorrow and scan for any pending codes. I'm really hoping its not the neutral safety switch itself. Looks like a PITA to change. being all the way on top of the tranny.

Please stop posting nonsense.

So I got a CEL this morning and pulled the codes. Got a P0704 and p0410. 704 I'm guessing was for the connector under the clutch pedal? I have yet to re check the connectors. but will soon. 410 is the air pump. I'm wondering if when I took off the UIM if I put back the vacuum hoses for the air pump back correctly. I think I did because I have no vacuum issues at idle or while driving. Any suggestions?

Bump... anyone know anything related to P0704.. checked all the switches/connectors under my clutch pedal and they seem connected fine. The code reads CPP sensor (clutch pedal position). Is there a certain way the sensor should face? Or should I just replace the sensor under the pedal?
I'm only getting a idle fluctuation when the car is in gear with the clutch down. It moves from 1k-1500rpm and keeps fluctuating until I drive or take it out of gear.

DTC P0704

CPP switch input circuit problem

DETECTION CONDITION

The PCM monitors the input signal from the CPP switch when the vehicle speed is more than 30 km/h {19 mph}. If the input signal does not change while alternately accelerating and decelerating 10 times, the PCM determines that there is a CPP switch input circuit malfunction.

Diagnostic support note

This is a continuous monitor (CCM).

The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.

PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.

The DTC is stored in the PCM memory.

POSSIBLE CAUSE

CPP switch malfunction

Connector or terminal malfunction

Open circuit in wiring harness between CPP switch terminal B and PCM terminal 4F

Short to ground in wiring harness between CPP switch terminal B and PCM terminal 4F

Open circuit in wiring harness between CPP switch terminal D and ground

PCM malfunction

^Thank you. I've ordered the new CPP sensor. Hopefully that solves this. Much easier than replacing the neutral safety switch.

UPDATE: Issue resolved. I installed the new CPP switch under the clutch pedal (insert and rotate clockwise) I realized it actually clicked or snapped in place? Rather than the old one which felt loose. No more idle bounce/surge. Car runs mint and holds a strong idle now. Also adjusted the clutch and feels strong. Now just to order the reinforced bracket or get mines welded as preventative maintenance is my next decision.

Yes, they snap into place, and both should have a retaining clip to make sure they stay there.

Yes retaining clip for the harness was also snapped in place. Thanks.

Hey guys, Sorry to bring up an older thread but this was the closest one I could find to my current problem.

I started getting the P0704 code about a week ago after attempting to teach the GF how to drive stick (Probably could have picked a better car for that) After many stalls, rough starts etc I ran my OBDII to clear the Cat code and noticed the P0704. Checked the switches yesterday and noticed the switch for the Neutral Switch circuit wasn't attached to the metal bracket.

Got the Switch attached to the bracket and all of a sudden I had cruise for the first time! But. the idle also surges back and forth to ~1k and back. Should I be looking into getting the neutral safety switch or the clutch position sensor? Is having it unattached from the clutch assembly hurting my performance?

Thanks for any help

Most likely the CPP switch needs to be replaced. It's a delicate switch and I realized after taking it out and putting it back in so many times I may have caused it to short itself out or get damaged in some way. I'd say replace it. Simple turn and click. The idle bounce is really annoying.. I know lol.

Hey guys, I am having some idling issues when the car is in neutral. It does not do it all the time and seems to only do it shortly after a cold start. When sitting in neutral the RPMs jump from 1000 to 1500 rpms and it continues to do it until either I press the clutch or rev up the engine. Once I rev up or put the car in gear it does not do it again.

Any help, tips, direction will be appreciated.

Thanks!

2006 Mazda RX-8 Shinka 53K

What is ur local climate right now? Cuz that sounds like ur neutral switch on the tranny causing the issue, it's a well known issue actually, new version of the switch solves the problem

Thanks for the reponse! Local climate is around 70 to 80 F. Is it difficult to change out the neutral swtich? Do you recommend the dealer perform the job?

Thanks!

If it does this every time u start ur car, u should get a cel after 3 times, or if u have a code reader u might be able to get a pending code, just to give u a better idea if it's really failing

Is it hard? Well if it's really that switch, it's located almost to the top of the tranny on the side. It's not exactly hard to get to it if u know what to look for and how to position ur arm.

I have not got a cel but I will have my buddy hook up his code reader to see if there is any pending codes.

Thanks!

Had the same problem with the idle fluctuation or cycling from 1000 to 1500 when in gear but perfect idle when in neutral (6 speed trans). Found the plunger was not fully releasing on CPP switch on the clutch pedal. The switch was coming apart which was causing the plunger to stick. A small tie wrap around the switch now holds it together and the plunger fully releases as the pedal is pushed down. Idle now is steady at 900 ish rpm.

I have an 04, and mine is doing the same thing. It idles fine in neutral, but bounces from .9-1.5k when in first. I just replaced my CPP but it's still fluctuating. Anything else I should check?