Background: Car has been home in a garage for the last 4 months while I'm away. Neighbor has been taking it out maybe once a month and letting it idle for a few mins.
60k miles on it, Hondata ECU, cat is removed, but normally runs just fine, no CELs, nada.

I get home tonight and try to fire it up - starts right up, but immediately revs to 2k rpm in neutral, then after about 10 secs drops to 1k rpm...then right back up to 2k. It alternates between 1 and 2k constantly after that. If I touch the gas, it comes back down and does the same thing.

I tried pulling the battery cable and resetting the ECU, no difference. I went ahead and took it for a spin and it does the same thing even in gear if it drops to 1k rpm.

My wifes Accord did something similar, it was a gunked up sensor in the throttle body. Could this be something similar? It didn't throw any codes at first, but I did get it to throw a code by yanking a connector on the TB (not sure which one...it was blue ) - which also caused it to stall out. But I reconnected and same thing.

Any ideas? Is it safe to drive like that?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andyep3 &raquo;</TD></TR><TR><TD CLASS="quote">My wifes Accord did something similar, it was a gunked up sensor in the throttle body. Could this be something similar?</TD></TR></TABLE>


Try using some TB cleaner on the IACV and TB. That may help.

 

Thanks.

That was gonna be my first shot, I'm kind of surprised resetting the ECU didn't change anything...
I'll post an update after I spray that sucker down.

 

It almost sounds like it's going through an idle relearn process. It's weird though because nothing you mentioned sure have triggered that (typical after swaps).

 

White,

how long does that last? I let it fluctuate the rpm for a good couple minutes last night (at least until it hit operating temp).

 

If a forced relearn doesn't work (Honda can try) it could take up 3-4 days to "cure." After my swap it took about 3 days but I've heard it could time up to a week.

When it was at it's worst, it would flutter from 1k to 2k but if I let it idle for ~2 minutes it would pulse from 1900 to 2000rpms. Sounded like some type of launch control. It seemed to get a little better after it rested for hours and I started it again.

 

hmmm...interesting.
i sprayed the TB area down with TB cleaner today, but not much of a difference.
however, i'm driving it around and notice that when i'm in neutral if I rev to 6k+ rpm, it will settle back down around 1k rpm. but if i shut off the car and restart it, it will go back to the pulsating rpms.
it is fairly random - 1.5k to 2.5k, 1k to almost 3k, etc.
i'm gonna try to take the bumper/intake off again and spray the TB down some more, it's been raining off and on all day so hard to do.

 

i had the same problem on my untuned greddy turbo kit ep3, after getting it tuned, the problem went away

 

Gah.
This problem seems to have gone away...by itself.
I just kept driving it and noticed that sometimes it would idle okay. Eventually it stopped the rev-ing and would idle just under 1k.
When I start it when the engine is cold, it idles around 1.5k and then drops down once I start driving. IIRC, this is normal (remember, I haven't driven the ep3 for 4 months!).

Anyway...I'm thinking it could still be a problem with the IACV valve or maybe a small vacuum leak somewhere, but for now I'll deal with it since I'm only in town for a few more days.

I found some good IACV-related links via google, I can post them if someone else thinks they might help...

thanks for all the help.