This is a '90 Legacy w/a '93 EJ22T swapped in - 130K miles. Has had a high idle (1800+) til fully warm since the swap - I've check vacuum lines. Cleaned the IAC and got a little better.

 

I swapped the front Coolant sensor out a week ago, which made no difference.

 

This a.m. on a 0 degrees day (-20 wind chill) started it up and it idled high but started to surge 500+ RPM - to 2500 RPM for just a second then would return to the 1800 RPM...also, the cooling fans would cycle on/off @ the same time.

 

 

After 5 mins it the surging ceased and after 10 mins the idle returned to normal - 700 ish RPM once it was warm.

 

The heater was on HEAT only- neither the Heat/Def nor the Def were on.

 

Any feedback is appreciated.

Are you getting any codes? Have you checked the tps? My ej brat had a surging problem that threw a code for the idle switch which is part of the tps. You might want to check the voltage at the ecu for the tps and the idle switch. Hope this helps.

 

Daniel

UPDATE:

 

I briefly (maybe 2 secs) got a CEL this am.....likely was there yesterday, too, but today I was looking for it.

 

However, the RPMs did not surge like yesterday.

 

I'll pull the codes tonite.

 

There was also a clicking noise coming from the front dash - w/the defroster on and off.

 

What relays sit under there?

 

 

At the risk of being focused on the wrong thing, I think this is due to the super cold weather.

 

We're to stay well before freezing, w/overnite temps below 0, for the next week!

replace the IAC o-ring.

replace the IAC o-ring.

 

I noticed this O-ring was loose when I cleaned the IAC, but not having an extra lying/laying around I put it back where I 'think' it went. Does it go around the 1st step or the 2nd step above the base? In the pic below the 2 steps are visible (thanks JC/Legacy777):

Edited December 15, 200817 yr by wtdash
credit JC

Codes are:

45: Pressure sensor and pressure exchange solenoid valve (I have an FCD installed)

and

49: Air flow sensor - Left over from when I temporarily had a different MAF installed.

 

Both should have been cleared, since I removed the Neg. batt. cable for over an hour after putting the stock MAF back in, and finished the FCD installed.

 

Car runs fine once warmed up!

Old post, but wanted to update since it's fixed (can't edit the original post).

 

Swapped in a used IAC and my high idle when cold is gone, and seems to have fixed a surging idle once warm it also had .

 

For the record, the wiring harness was from a '91 turbo - my engine and IAC were from a '93 turbo. The replacement IAC was from a '91...shouldn't matter, though.

 

I'll have to wait 'til next winter to see if fixed the <0 degrees F issue, too.

Edited May 19, 200916 yr by wtdash