PaGEmaZt3r

2003 AP1

New plugs
Cleaned Iac valve
New coil packs
Cleaned TB
Map whack
Valves Adjusted
Premium fuel only
ECU relearn
Checked injector resistance
Did a bunch of other crap as well..


Rebuilt engine with about 4,000 miles

Developed a low idle. Car performs well while driving with no loss of power but idle is lower than normal and car falls on it's face at an abrupt stop.

I'm going to check the compression as soon as I get a chance to eliminate loose/tight valves (which would be my fault) and or compression loss through the piston rings.

Would anybody be willing to chime in and throw me some other ideas? I had a thought that maybe not bleeding the coolant system like I seen in the DIY could maybe cause a low idle?

Car has heat and never goes above 3 bars..

Thanks in advance! Any and all advice will greatly be appreciated! If I can't fix this I'm going to push it off a cliff while singing kumbaya with a fifth of jack.

MR.T

Believe it or not, I solved mine with a new battery. I had been noticing voltage dropping down to the low 12's when my comp or fans kicked on (have a scan gauge). Then I had a couple of no starts after short trips.

Figured I'd replace my 5yo battery, did an idle relearn and problem solved. i still get a tiny bit of stumble when backing up through parking lots (light on the throttle) but the problem is about 90% squared away.

How did you clean the iacv? Did you actually disassemble and free up the rollers as billman suggests?

Some have had success with cleaning out the port that feeds from the tb to the map. I think they just use alcohol, but don't quote me.

Others have had success with replacing O2's.

I really doubt it's a low comp issue. Sounds like the normal stumble/shake/idle drop that so many have been tracking down.

Don't forget to idle relearn after each fix.

I'm sure you know this, but:

1.Start car
2.Hold to 3k until fans kick on
3.Then let idle for 5 mins.

On a completely cold car, I've had my idle go crazy trying to hold it to 3k, so it may require letting it warm a bit, then pull the fuse and do a relearn.

MR.T

Beyond all that, replacing the iacv might be a good place to start once you've exhausted all of the free/low cost options.

PaGEmaZt3r

First, Thank you MR.T for your input! And yes I followed the Billmans DIY on cleaning the IAC valve and also the port on the intake. I also cleaned the MAP port when I cleaned my Throttle Body. As for the battery I never have thought to change it but I can test it to make sure!

And yeah I always reset the ECU and follow the relearn idle process.

PaGEmaZt3r

Had a cel come on.

P1519: IAC Valve Circuit Malfunction.

I had the connector off while the battery was hooked up so I think it was just that. I made sure the connector was plugged in and restarted the car and cleared it. Hasn't came back on.

Now there is a weird popping noise come from engine bay...

PaGEmaZt3r

Anybody else have input? Lost on what I should do next.

PaGEmaZt3r

After pouring over the forums for the last 3 hours I've came to the conclusion I should just replace my IAC with a brand new one. I guess my next step will be a leakdown to did if I'm losing compression and burnt or bent a valve. When I rebuilt the engine I bought a used head from a member and let my machine shop rebuild it. The only thing I had to replace was the exhaust valve guides and they said it was good to go. Maybe it wasn't?? Maybe the valves are done for? Could this be a possible reason for my low idle? Keep in mind the car performs excellent the low idle issue only occurs while it's sitting or when I come to a stop. Please please please help!

MR.T

What work had you done since your first post?

You might want to go into detail concerning the popping noise.... Maybe video.

s2000maniac

I just bought a brand new IAC valve coz I had the old one cleaned and it kind of fixed the issues but it came back. You can buy the IAC from Advance Auto for like $100. Buy the one that says "wells electronics" it's actually made in Japan by DENSO. Also it comes with a lifetime warranty. You can use the "TRT30" coupon for 30% off. Also replace those coolant hoses that go into the IAC valve coz once you take them out, the seal breaks and it they will start leaking coolant under pressure. I think if you had bad valves you would probably get misfire at idle. Good Luck!

Billman250

I dont think I have a diy on iac valve. How did you clean it?