Erratic idle

Post by **Legacy777** » Thu Nov 24, 2005 6:27 pm

After my engine swap, I've been having issues with the idle. It doesn't want to idle worth a crap. The rpms will drop pretty quick, the idle will bounce back up....sort float around 1000 rpm, and then drop to 500, bounce up to 800, down to 400-500, and back up....it continues doing this.

It seems a little better after I have driven the car for a little while. However it's not like that all the time. With the A/C on, idle is fine.

The things I have in question are the IAC itself, the IAC wiring (I need to look at the FSM again), and fuel pressure (I'm wondering if the stock fpr is not equipped to maintain the correct idle pressure, therefore I'm getting too much fuel at idle. I've got a gauge and will be testing that soon). The only other thing I can see that might cause an issue is the LW flywheel.....however that might be a stretch. It would explain the fast drop in RPM, but I'm not so sure it'd explain the idle.

I need to grab a buddy to watch the select monitor while I drive around, and see what some of the sensors are doing.

Any thoughts?

BAC5.2 · Post by **BAC5.2** » Thu Nov 24, 2005 8:12 pm

Sounds like the IAC. Mine did that for a while, then it started idling at 2000 or so.

My flywheel hasn't caused that kind of idle, so no reason yours would. My IAC behaved and idle was fine when the AC was on, but was fucked up when the AC was off.

I bet it is IAC related.

Post by **Legacy777** » Thu Nov 24, 2005 8:46 pm

Did you replace your IAC valve and have the problems go away?

If so, did you replace it with a used one or new one?

I looked at the wiring in the FSM, and everything looks good. If fuel pressure is good, you're probably dead on with the IAC being the issue.

I wonder if the issue is the valve itself or the electronic part. I wonder if swapping the electronic part from my other valve would help....hmmm

legacy92ej22t · Post by **legacy92ej22t** » Thu Nov 24, 2005 10:16 pm

I had similar issues after my swap. Things slowly got better until it hardly ever did it. Then it came back and started doing it again. With me it was the same, with ac on it was perfect, with it off I'd get an irratic idle.

Do you have a lw flywheel and a lw crank pulley?

BAC5.2 · Post by **BAC5.2** » Thu Nov 24, 2005 10:53 pm

I replaced the IAC valve, and the wiring, and things got better.

I have a brand new IAC valve for sale, if you want.

Post by **Legacy777** » Fri Nov 25, 2005 6:29 am

legacy92ej22t wrote:I had similar issues after my swap. Things slowly got better until it hardly ever did it. Then it came back and started doing it again. With me it was the same, with ac on it was perfect, with it off I'd get an irratic idle.

Do you have a lw flywheel and a lw crank pulley?

Yup, got both LW flywheel & LW crank pulley

Post by **Legacy777** » Fri Nov 25, 2005 6:30 am

BAC5.2 wrote:I replaced the IAC valve, and the wiring, and things got better.

I have a brand new IAC valve for sale, if you want.

What did you do for the wiring? So you replaced the IAC valve....did you replace it with a new one or old one?

How much do you want for the valve? I'd just hate to spend a couple hundred dollars for an IAC valve, and it not fix my problem.....

entirelyturbo · Post by **entirelyturbo** » Fri Nov 25, 2005 6:34 am

The first thing I was going to bring up was the LW flywheel/pulley.

How much have you driven it since the swap? Maybe the ECU just needs to learn how to work the IAC, taking the LW stuff into account, before developing a proper idle?

Post by **Legacy777** » Fri Nov 25, 2005 6:42 am

Probably about 200 miles or so. I'd have to check for specifics.

douglas vincent · Post by **douglas vincent** » Fri Nov 25, 2005 8:02 am

Ok, here is a shot in the dark.

Hook up a multimeter to the MAF signal line and monitor it.

Start the car up with your lights on and warm it up and let it idle, at this stage I am assuming you have idle problems.

Now at idle, watch the MAF signal. Turn the lights off. Does the idle improve? Does the MAF signal increase?

Step on your brakes, does the idle problem worsen? Does your MAF signal decrease?

This is my problem. I suspect either bad ground, or my alternator is not putting out enough juice at idle.

BAC5.2 · Post by **BAC5.2** » Fri Nov 25, 2005 8:02 am

I replaced my IAC valve with a new one. There was a big mess at the dealer, and I ended up with two new valves.

I pinned directly off of the ECU and ran wires directly to the IAC and got power from the coil. Vikash gave me a hand on it.

I'll PM you.

Post by **Legacy777** » Fri Nov 25, 2005 5:05 pm

Doug,

I've got a select monitor. I'll check out the MAF sensor voltage

simbey1982 · Post by **simbey1982** » Fri Nov 25, 2005 9:39 pm

Josh,

I have a LW flywheel in my Impreza and ive known people with both LW flywheels and LW crankpulleys and no idle problems.

I would agree that it may be your IAC or with reddevil

See ya

Cory

Post by **Legacy777** » Sat Nov 26, 2005 7:42 am

Doug,

I looked at the MAF signal. It does bounce from 1.06 to 1.10 or something like that at idle....but I would consider it normal.

douglas vincent · Post by **douglas vincent** » Sat Nov 26, 2005 7:51 am

Wow, mine reads .18 to .40 at idle.

Post by **Legacy777** » Sat Nov 26, 2005 7:59 am

Yeah it shouldn't read that......probably because you tweaked with the gain.

vrg3 · Post by **vrg3** » Tue Nov 29, 2005 9:05 pm

Realize that the airflow number is going to bounce around if RPMs are bouncing around, no matter what. The Select Monitor masks some of this because of its relatively low sample rate; my scantool is a little better in that respect.

legacy92ej22t · Post by **legacy92ej22t** » Tue Nov 29, 2005 9:52 pm

Legacy777 wrote:
legacy92ej22t wrote:I had similar issues after my swap. Things slowly got better until it hardly ever did it. Then it came back and started doing it again. With me it was the same, with ac on it was perfect, with it off I'd get an irratic idle.

Do you have a lw flywheel and a lw crank pulley?
Yup, got both LW flywheel & LW crank pulley

OK, I do too and I've had similar issues. Maybe the EJ22T doesn't like being lightened at both ends of the crank.

I never throw an IAC code but the symptoms seem like a bad IAC. I'm planning to remove my lw crank pulley and go back to the oem crank pulley, if I get a new tranny that is. I was hoping maybe that would cure the problem.

LaureltheQueen · Post by **LaureltheQueen** » Tue Nov 29, 2005 11:12 pm

*erratic

Post by **Legacy777** » Fri Dec 02, 2005 3:45 am

LaureltheQueen wrote:*erratic

Thank you my dear

Post by **Legacy777** » Fri Dec 02, 2005 3:47 am

legacy92ej22t wrote:
Legacy777 wrote:
legacy92ej22t wrote:I had similar issues after my swap. Things slowly got better until it hardly ever did it. Then it came back and started doing it again. With me it was the same, with ac on it was perfect, with it off I'd get an irratic idle.

Do you have a lw flywheel and a lw crank pulley?
Yup, got both LW flywheel & LW crank pulley
OK, I do too and I've had similar issues. Maybe the EJ22T doesn't like being lightened at both ends of the crank.

I never throw an IAC code but the symptoms seem like a bad IAC. I'm planning to remove my lw crank pulley and go back to the oem crank pulley, if I get a new tranny that is. I was hoping maybe that would cure the problem.

Yeah....I don't know.....it's gotten a little better after some more driving, but it still isn't right. It's more then likely the IAC valve. I just hate to spend the money and it not fix the problem. If I knew 100% that swapping out the IAC valve would fix the problem, I'd do it.

Post by **Legacy777** » Wed Dec 07, 2005 4:25 am

I noticed something interesting with the select monitor. The duty % on the IAC valve is at 40%, which is at the top end of the limits. So I'm thinking about tweaking the electro magnet portion a little bit, or swapping out the one from my other IAC valve.

Post by **Legacy777** » Sun Dec 18, 2005 5:18 am

I was coming back from the dyno today, and idle was still doing it's normal thing. Apparently it left a code for the IAC valve, I didn't notice the check engine light though.

The code was in memory, and not a current code.

Well, I decided to try something. I pulled the electric part off the valve from my na motor and put it on the turbo valve.

The electric part is slightly different. The 90 one has a little step in it. The 90 electric part fit on the turbo valve fine. However the turbo electric part won't fit on the 90 valve.

What I did was align the electric part similarly to where the old turbo one was. It started and ran, but idle was low and worse. I then turned the valve a little until the IAC duty % showed about 35%.

She idles fine now. The idle doesn't seem to drop as quick, like it did with the old valve. RPM's with AC on seem a little higher, but that's probably "normal"

I wouldn't say the idle is as smooth as new car or what not, but it's much better!! I might have been able to tweak the turbo electrical part, but with it throwing a code, I didn't know if it had issues.

here's pics of the 90 valve and turbo electrical part.
http://www.main.experiencetherave.com:8 ... /iacvalve/

Alvaro Alonso · Post by **Alvaro Alonso** » Wed Dec 21, 2005 2:15 am

simbey1982 wrote:Josh,
I have a LW flywheel in my Impreza and ive known people with both LW flywheels and LW crankpulleys and no idle problems.

I have completely stock NA wich idles erratically sometimes after starting the engine.
This may discard LW flyw & crankp as the cause.
I have not tried AC button.
"Idle dancing" dissapears after....
driving for a while
manually (footally?) adjusting idle by depressing throttle for a while. may be up to warming up?.

Some afterhours toughs:
Secondary effects of my erratic idle are lights dimming, so there must be a voltage drop...... obviously the alternator may not be generating enough power when it goees down to 500 rpm...

This seems a bad closed loop (actuator or controller or sensor is bad) entering a resonance until some conditions change (temperature, throttle). There must be the problem.

but the battery should give enough current, not allowing lights to dim.... mmmmm...... Why do they dim?
Who is stealing the power

the battery is new and it is fully charged

So, if battery is ok, something is draining lot of Amps (actuator) elsewhere but it is fixed after warm up or injecting more fuel (alternator gets rpm it needs and supplies extra power).

It seems to me there must be a mechanical problem on some actuator being stuck when cold.

What do you think?

Off topic part:
when checking ecu codes, CEL keeps flashing forever (no code), Is there a problem? or no codes to be read?
( I'm confused somewhere I read "constant flashing cell=no trouble", elsewhere I read "no cel =no trouble"!!!! )

bmxpunk · Post by **bmxpunk** » Wed Dec 21, 2005 4:09 am

josh my car has similar idle issues, when it is cold, it wont idle. I have to sit in the car for tw ominutes and hold the accelerator down for a few minutes. I think it has to do wit hthe fact that the Iac from my 1.8L was different than that of my 22t. they do however have the same plug. I dont know.

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Erratic idle

Erratic idle

Hmm

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