January 30, 20188 yr 1993 Impreza FWD been wondering for about 6 years now, whenever im going over 45mph, say when im getting off of the highway i go into neutral (manual transmission) the idle stays above 1,200-1500rpm. it only finally drops back down to 750rpm where its suppose to be when im decelerating past the 45mph mark. its not a gradual decrease of rpm's with the speed im going, it just drops back where its suppose to be when im decelerating and it passes 45mph (slowing down/coming to a stop) it's never affected anything but just something im curious about. is it in the computer itself so its easier for me to release the clutch and continue on driving if i need to? turning the engine off and on makes the RPM's go back to 750 even though im going 70mph but once i rev it alittle, it then stays above 1200-1500 revolutions, its quite funny, almost like a One Way Wall, and the "problem" hasn't gotten worse or better if it's even a problem the last 6 years of owning the car. just something i've wondered, thanks!
January 30, 20188 yr Most likely the neutral switch on the transmission is bad. You can ohm them out up on top the trans. One small plug is for reverse the other is for neutral. Open/closed switches as you shift. If the ECU does not know the trans is in N the Revs will be high.
January 31, 20188 yr Author I agree about the neutral switch, but my bad on my end, it also does it with the clutch pedal depressed or neutral with the clutch pedal released. Although never knew there was a neutral switch on this transmission! So thanks for that info Just something that bugs me seeing the revs just stay up like that only at highway speeds while the rest of my carburetor vehicles stay where they’re suppose to like a normal car should, it’s not 3,000rpm extreme but it’s a 1,500rpm noticeable
January 31, 20188 yr Have you cleaned the IAC? A good start is some Seafoam down the 1" hose going to the IAC. Let it sit 20 minutes or so and then start it up. Expect lots of white smoke.
January 31, 20188 yr Author Have you cleaned the IAC? A good start is some Seafoam down the 1" hose going to the IAC. Let it sit 20 minutes or so and then start it up. Expect lots of white smoke. i've put some down the intake with the plastic intake removed but never poured it directly down the 1" rubber tube that goes to the IAC, ill try that this afternoon and let you know what happens, ill also double check if the 4 screws are tight on it.
January 31, 20188 yr Clutch pedal location has no bearing on the neutral safety switch. I had a similar issue with the wifes 01 , cleaned then replaced the iac ... then i swapped out the neutral switch and idle issues are gone.
February 2, 20188 yr All the Loyales I had worked just like that, on purpose, as far as I could tell. In fact, the Loyales keep it at 1200+ until you coast to a stop, then drop. The only one that doesn't, has a problem with the IAC, so idle is always a bit off. I had a theory it was to keep the oil pressure up, but that is probably wrong. Maybe it is to make it easier to slide it into gear, as both the input/output/internal shafts are closer matched in speed?
February 2, 20188 yr There is a reverse switch and a Neutral switch. Both are on the side of the MT. I seem to recall that the switches have different colored connectors but can't recall which one is which color. It's the rear one https://parts.subaru.com/a/Subaru__/49242870__6027485/MT--REAR-CASE/B11-120-01.html Edited February 2, 20188 yr by Mike104
February 2, 20188 yr Mike is correct , the switch is called a neutral position switch. The neutral safety switch however is on an automatic. The second switch on the MT is reverse lights
February 2, 20188 yr Author so I did the sea foam on the IAC and to no change, unsuprisingly, screws are still tight and fine. whats got me wondering now is i know an 89 and 90 GL/Loyale don't do the idling issue while coasting as i've owned both of those and still do, but my 1994 Loyale does the same idling "coasting" issue as my Impreza, which is now a parts vehicle so the only vehicle remaining that has the idling "issue" is the impreza. Manufacturing date on the 89 GL is 06/89 while the 90 Loyale is 07/89 any thoughts? im wondering if Subaru sometime in the early 90's implemented it on the ECU on all vehicles and future cars up to a certain year? Edited February 2, 20188 yr by Subasaurus
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