OK, so first i want to say that i have already searched. I have tried everything but replacing my IACV. I would like to know if there is anything else i should try or what else could be causing it in the even that i replace the iacv and it still surges.

some information:
H22a with Euro R intake mani, skunk 2 TB (so the FITV is eliminated)
revahard stage 2 kit (running an FMU to work out little bugs before i get it tuned later this month).
EGR system is blocked off

I have pressuized the intake system, as well as sprayed carb cleaner to detect intake leaks and there aren't any.

burped coolant system

I have read before that if you put your finger over the port in the throttle body for the IACV and it stops surging then the IAC is bad. I have done this and it does in fact stop surging when i cover the hole...

other than a new iacv coule it be because im running the h22 ecu and not a P28 yet?

any input would be nice

thanks in advance!

 

I blocked my egr valve off too. What did you do with the vacuum hose that is connected to the right side of the intake manifold? My idle jumps up and down ever since I took that off and I have tried EVERYTHING and it still won't go away. Your IAC probably won't help though because I did that too. It idles just fine though when I plug one of the holes in the throttle body. I just forgot which one right now. O wait, I have an H23 though...

 

I'm thinking about trying this: http://92lude.com/idle_air_control_bypass_mod.htm

he says on that website that if it sucks air or if it stop surging when you plug it your iac is bad. Mine does both. I have a eruo R intake mani but i think i know what port your talking about. if its what I think it is i just capped it off...


anyone else? haha

 

Yeah, that is the other website i signed up to and I also did that modification. I bought a new IAC Valve and then I did that mod. Neither helps out though and I'm getting really annoyed with the surging...

 

usually the iacv, I have had to fix this problem in four cars in the last week and 3/4 were the iacv, the other one, the guy went in and adjusted the screw inside the iacv and that broke and needed replacing.

 

when u guys are takeing off your egr. u r capping off the vacume port in the side of the intake manifold rite?

 

also surging can be cause by a few things. like vacume leak,iac problem,running to rich or lean,bubble in coolant.

 

well like i said, i tested for vacuum leaks, burped the coolant, and although its an FMU i looked at the AFRs with a wideband and its not too bad its a little rich and yea everythings capped off

 

have you tried testing the IAC valve to make sure its bad? you can unplug it while the car is on, if it drops in rpms then its working. If it does not drop in rpm's its bad

 

Well, when i unplug it it'll stop surging but it still idles too high. Normally (like when setting the idle) when you unplug it, the car idles very low. when its surging it goes from around 900-1400 when i unplug the iac it stays around 900...i'm thinking i need an iac. I'm gonna try that spring thing from 92prelude tomorrow and ill let you guys know if it works.

bed time

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H22EG413 &raquo;</TD></TR><TR><TD CLASS="quote">Well, when i unplug it it'll stop surging but it still idles too high. </TD></TR></TABLE>

Assuming you have no vacuum leaks... there is an idle adjust screw in the throttle body. Screw that in until it idles around 700 with the IACV unplugged. Refer to the Helm idle adjustment procedure...

 

like i said i checked for vacuum leaks. yea i know the process for setting the idle usually when you unplug the iac itll drop and you use the screw to set it around 650-700.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1994PreludeSi &raquo;</TD></TR><TR><TD CLASS="quote">Yeah, that is the other website i signed up to and I also did that modification. I bought a new IAC Valve and then I did that mod. Neither helps out though and I'm getting really annoyed with the surging... </TD></TR></TABLE>than u my friend might have a possible vacum leak..make sure all the hoses are plugged

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H22EG413 &raquo;</TD></TR><TR><TD CLASS="quote">yea i know the process for setting the idle usually when you unplug the iac itll drop and you use the screw to set it around 650-700.</TD></TR></TABLE>

Well you said it was idling too fast with the IACV unplugged, so the manifold is getting too much air from somewhere. Maybe the IACV is leaking, maybe the throttle cable is not adjusted right, maybe the butterfly stop is set wrong, maybe the gaskets between the TB and IM or between the IM and head are leaking. It can't be that hard when you know that it's idling too fast with the IACV unplugged...

 

i think i found the problem, im gonna finish putting it back together tomorrow and ill let you know.

 

I had the same problem with my prelude....i tried all the steps that i got from different fourms but nothing worked.....Finally i took the intake off and found damage on my intake manifold gasket. That fixed my problem.

 

I'm thinkin Its the ECU because I tried my P28 instead of the P72 and it's stopped surging sooo we'll see when it tuned




Modified by H22EG413 at 9:18 AM 4/7/2007

 

I had the same thing happen. When I plugged in a P28 ECU in my car ran great. When I put back in the OBD2, H22a4 ECU it ran like ****.

 

im having the same problem with the idle surging. but mine surges only when its cold out. what does this mean.???

 

could be the FITV is bad or needs fixing, search the prelude forum for surging and try some things, i THINK i figured mine out..we'll see at the end of the month when I'm running the P28

 

I got a chipped P06 now, the car is not stalling but it ran alot weird. I was told to unplug the evap canister and it should fix the problem.

 

its weird that an emissions device would cause a car to surge...id be surprised if unplugging the evap would solve any problems but I'm not certain.

 

It could a vacuum leak, you could check the vacuum diagram lines. that fixed mine, ive been having that problem before and its never been the iac,its the vacuum lines.. do u have any electronic devices there like air fuel controllers?vtec controller? i used to have the sfc vtec controller and I noticed that everytime the car hit bumps the car runs like crap,so you could also check that too. anyways hope you fix the problems.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by preludeh22a1 &raquo;</TD></TR><TR><TD CLASS="quote">It could a vacuum leak, you could check the vacuum diagram lines. that fixed mine, ive been having that problem before and its never been the iac,its the vacuum lines.. do u have any electronic devices there like air fuel controllers?vtec controller? i used to have the sfc vtec controller and I noticed that everytime the car hit bumps the car runs like crap,so you could also check that too. anyways hope you fix the problems. </TD></TR></TABLE>

i have air/fuel gauge and vacum gauge. also vafc. mines still does it. i searched it but nothing that i havent heard already. so whats the deal. is there anything that could slecifically trigger the idle surge in cold weather because thats the only time mines will do that.