IW STi Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1
My car recently developed a very odd issue that I can't seem to figure out and I thought I'd turn to the forums for some help. Recently, after my car has warmed up, if I'm moving with the car in gear with the clutch in, the RPMs will rise to about 2000 rpm and just stay there. So say I'm sitting in traffic moving along in first gear. If I push the clutch in, but leave it in gear, the rpms initially drop to idle, but then slowly rise to 2000 rpm. They will only come down if I pull it out of gear, or come to a stop. It will do it in any gear too. I've also noticed that sometimes it will rise to 2000 rpm then drop to idle then rise again, just repeating this until I stop moving or pull it out of gear.

My initial thoughts are something with the neutral position switch on the transmission. As I said it has something to do with being in gear, and as far as I know, that's the only way the ECU knows the car is in gear. My cruise control also doesn't work in the sense it won't set. It used to set briefly, then cancel itself randomly, but recently it won't set at all. This leads me to believe they could be related.

I just wanted to see if anyone else has ever had this issue, or has any other suggestions on what it could be. Also, the car is completely stock engine wise and it isn't throwing any codes. It runs great otherwise and this only seems to happen after the engine warms up to operating temp. Any help is greatly appreciated!
 

·
Registered
Joined
·
20 Posts
Discussion Starter #2
I wanted to give a quick update to hopefully help someone in the future. I got a new neutral position switch that I did a quick test with in the car. I just plugged it in, zip-tied it out of the way, and went for a test drive. I taped the plunger on it down to simulate being in gear and my cruise control started working and the car drove very different. So this confirmed that my current switch is bad and my car always thinks its in neutral. I'm thinking this is what was causing my idle issue as I've read that sensor can affect AVCS and idle. Now I need to actually replace the sensor on the transmission. I've done some searching on the various forums on the best way to go about replacing it, but there isn't too much information. The service manual says to remove the transmission, but I want to avoid this if I can. Has anyone changed this switch before without dropping the transmission? I attempted to change it yesterday, but I couldn't buy myself enough room to reach the switch with removing the transmission crossmember and pitch mount. Any advice would be greatly appreciated!
 

·
Registered
Joined
·
495 Posts
Where is the switch located? if its near the rear you could try removing the rear drive shaft and engine mount and raising the engine. That might make the transmission fall at the back and gain you some room.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #4
I just wanted to give a quick update on this to hopefully help someone out in the future. I was finally able to change out the switch and it seemed to fix all of my problems. The idle is back to normal, my cruise control works, and the car seems to be driving better. Shifting is more consistent, whereas before sometimes the revs would drop quick or sometimes they would hang. You can see how worn the switch was (old on the left, new on the right)



In terms of actually changing out the switch, it was quite the struggle. I removed the intercooler and pitch stop, transmission crossmember, and rear shifter stay. I also loosened the carrier bearing on the driveshaft which helped give me a little more room. You have to reach up on top of the transmission from the passenger side where you can reach the switch with a stubby 19mm wrench. It's in there pretty good, so I had to get creative to break it free, but once it broke loose, it came out no problem. Getting the new one in was pretty easy, just reverse of removal.
 
1 - 4 of 4 Posts
Top