Bouncing Idle...ECU/Vacuum Related?

[AccordWarrior]

Hi all,

My car has a very frustrating problem as of late. The idle will bounce like nuts when I come to a stop then maybe 20 seconds later it's fine.

When I'm pulling up to an intersection, I'll put the clutch in and hit the brakes. My idle drops almost all the way down to nothing (~300 rpm) and it feels like the car is going to stall out on me. Then the idle will bounce up to maybe 1200 rpm, and then down again a few times, before defaulting back to ~750 rpm.

It's just really annoying because it makes me nervous about the car. Some issues that might be related include:

- I recently had a battery issue where my terminals cracked, so the battery was always coming off and thus always resetting the ECU. I've since fixed it and properly reset the ECU, which usually works for a couple of weeks.
- I have an AEM CAI, so I left the hose that is supposed to be filled with foam open, since I haven't found the correct foam yet.
- I removed that box by the stock airbox that was for noise, and I cut short the vacuum hose from the intake. I plugged the hose with a screw.
- I have been listening to my stereo louder because my windows are down, but I don't know what type of load that puts on my car.
- My IACV valve has recently been cleaned.

All of my searching has shown a lot of topics with "Clean your IACV" as the answer, and I've done that...or people just don't know what else is up.

I haven't touched any of my adjustments yet, so I don't know what to make of it.

Any leads so I can look into it this weekend? I'm not showing a CEL or anything of the like, and this only happens sometimes, when the car has been warmed up and I come to a stop hitting the brakes. I'm pretty sure if I rolled to a stop, nothing would happen, and once the idle straightens itsself out, its fine. I feel like there's something that should kick up the idle when there's load on the car that's not kicking in or something.

Thanks in advance.

[blackice]

I dealt with idle issues for awhile after I got my car. I ended up replacing my iacv and fitv which seemed to help a little. Did you screw down the white thing in the fitv already? Then I cleaned and actually blocked off my egr valve since I didn't have time to drill the service ports. I'm sure you checked for vacuum hose leaks already. Did you bleed the radiator and make sure there are no bubbles? Also is your tps adjusted? Mine has screws holding it down so is easy to adjust but most engines I have seen have them held in with non adjustable studs from the factory. Another thing to check is your base idle. After checking and messing with all of the above my car still had the idle hunting problem. I ended up getting an aftermarket tach and found out that my stock tach was reading 400rpm too low (showed 800 while I was really at 1200). When I reset my base idle (now shows around 500 or so on the stock tach) the problem disappeared.

[mondojackal]

ok mike. its one of many possible things, i have the same problem, and it plagues me. ugh. i hate it, hate it, hate it!!
ok, so anyways, off my soapbox. IACV, FIV, FITV, flushand clean radiator/cooling system, TPS, EGR valves, or vacuum leakages. all of those are the possible culprits. some work for some people. some dont. i've personally done everything except the TPS. i was checking in my haynes manual. and it speaks of the TPS having the oscillating idle, and also doing the popcorn popping sounds under the hood (which mine does) and also losing power and running very lean. my motor will lose power and then throw a 43 CEL (fuel supply system..idk if its "43", but i think it is.) it will also throw a fuel supply system CEL if i let off of it without clutching it.. like when i let the motor slow the car. on hills and such.

[LinX]

I agree 100% with the possible problems listed. I had an idle issue when I swapped the h23 manifold and discovered alot about vacuumes and cooling. Check for ANY vacuum lines that could have leaks or any ports that might not be closed off. FITV should be tightened all the way because this DOES make a difference once the car is warmed up and running normal. IACV should be cleaned and put back on. The hose that leads to the intake is not necessary. You really don't even need the air boost valve so thats not the culprit. It might be the TPS if its not adjusted right but I don't know why this would go out of whack all of a sudden. Radiator cap might need replacing.

[NAiL05]

Sometimes cleaning the IACV wont work and you might have to buy a new unit. You could also check out the TPS as mentioned.

[Phempa]

this used to happen in my old CB7

wound up being a leaky vacuum tube


funny thing was, when I turned my headlights on, it wouldn't do it at all.
it would stop immediately


still kinda stumped about it.

[Bongo]

i had the same problem a little while back. it started right after i put on the SRI. the idle would do the same exact thing as yours so i stood there and looked around, and the hose that goes into the intake tube was pinched because it wasn't long enough so i just got a new one about 3 inches longer so there's no kinks in it or anything and that fixed it, haven't had any kind of problem with it since. so maybe check that?

[xfactortype1]

I'm not showing a CEL or anything of the like, and this only happens sometimes, when the car has been warmed up and I come to a stop hitting the brakes.

I have an AEM CAI, so I left the hose that is supposed to be filled with foam open, since I haven't found the correct foam yet.

i agree with everyone here that it most likely your iacv valve having trouble adjusting to load. does anyone else think that it could be a brake booster or master cylinder causing it? get the correct foam, just as long as it not to thick.


regards x

[Torqstr]

tube filled with foam?? anyone care to enlighten me? I don't think I have a tube filled with foam, that could be part of my problem.

Please let me know which hose it is and what where to get "foam".