1999 Legacy L Wagon 2.2L - Strange Idle & RPM Woes

Hey all, first post here. I just picked up a 1999 Legacy L Wagon 30th Anniversary Edition. 1 owner, super minty, and only 48,000 miles. It is a 5 speed and I recently flew down to Orlando to check it out before I had it shipped home. The seller let me drive it for an entire day. I was told it has a brand new clutch and timing belt, as well as all fluids. I have seen paperwork to confirm this and confirmed verbally over the phone with the shop. The car drove absolutely perfect in Orlando, so I bought it and had it shipped home to Chicago. The only thing that didn’t work on the entire car is the cruise control, so I got a couple hundred knocked off the price.

 

Anyways, once I got it here to Chicago, two problems arose:

 

1. The idle fluctuates up and down between 500 and 1200 RPM. It does this once the car warms up (on cold start it idles at 3000 rpm briefly before settling down to about 1200 and then I take off, not fluctuating though).

 

2. If I drive in first or second gear and push the clutch in over 3k Rpm’s, the idle will literally just hang there, and not lower, at all, until I either put the shifter into neutral or shift into the next gear (mind you with the clutch still engaged, I don’t even move my left foot off the floor and shift into neutral and the RPMs drop like a rock, like normal).. It’s to the point where if I’m short shifting around town, I am having to “pull” the RPMs down by engaging the clutch, which obviously isn’t good for it. If if shift above 4k RPMs it generally feels normal.

 

It DEFINITELY did not do any of this down south in the warm weather, and I’m kind of disappointed as I paid top dollar from a dealer for this car given the impeccable condition and low mileage. I just wanted to post on here to get some advice as I begin troubleshooting these two problems which I hope are related. The way the RPMs just hang until I put it in neutral really worries me, like they messed something up with the clutch. But I’ve also heard some people say that the ECU is designed to do this to keep power flowing to the accessories when the wheels are moving, then why does it drop when I switch to neural (with clutch still in)? Either way, it never did this is Orlando and I’ve never driven a manual car that has ever done anything like this.

 

I’ve read a lot of threads on here and first off, there are NO vacuum leaks that I can find anywhere. Everything is tight.

 

I have ordered a new IACV to swap in because it sounds like this may be causing my fluctuating idle issue. I have also ordered a new coil pack, wires, and plugs since that just needs to be done. When I put the IACV in, I will also throughly clean the throttle body.

 

I have heard faulty cruise control can also cause some of these issues but when I’m looking at the engine at idle while it’s fluctuating, the cruise cable is fully slack, so it’s not pulling on anything. The throttle body is not moving at all. I suppose it could be at speed with clutch in. Should I completely disconnect and remove the cable from the cruise actuator and give the car a go to see if that solves anything? I know the vacuum line for the cruise control is super brittle and probably not air tight.

 

Any advice and insight is greatly appreciated as I begin to tackle these issues in my spare time. I hope I can get this thing back to normal, and that they didn’t mess up my clutch. I really love this car, and it’s so clean, and to correct a botched clutch job would be expensive because I will not tackle that myself. Thanks again in advance

 

Edit: I just realized how long this post is and I apologize lol. Thanks for reading the entire thing to those that do!

Here is a photo of her:

 

Edited November 30, 2021 by Jayskerdoo

I would bet IACV, they can be cleaned but it's tedious so a new replacement will save time. You could also try loosening the throttle position sensor while it's running to see if that changes anything. It's just 2 screws, don't remove them, only loosen slightly and then just twist the sensor a little to see if it continues to pulsate. This will obviously change the idle RPM but I'm curious to see if the car doesn't actually know where the idle is set and is compensating somehow.

Coolant temperature sensor and wiring is the last thing I can think of that wasn't already mentioned. Unless it is the same temp in Chicago right now as it was in FL a couple months ago.

Well, I disconnected the cable on the throttle body from the Cruise Control Actuator (the one on the drivers side of the firewall) and BOTH of the above mentioned issues have been resolved. I swear I was seeing slack in the cable at idle when watching the RPMs fluctuate… maybe I wasn’t thorough enough.

 

Thanks for the help all. I think I will transition this thread into a cruise control fix, thread. My vacuum cable is so crusty it just falls off so it’s definitely not sealing. But I don’t hear a click when trying to engage cruise. I do see the light on the button. Going to look at the switch by the clutch pedal first.