SilverPhoenix

Howdy,

I decided to clean out my throttle body, intake manifold and EGR the other day, checked the IACV and cleaned that out as well. Everything was pretty dirty in there and it took about 3-4 bottles to flush things out. I took care to keep the throttle body/IACV free of water. I don't think that I lost very much coolant. I put everything back together about a day and a half later, and now the idle is going up and down periodically. I have not yet driven the car. The engine light is on as well, but I have no way to tell the codes yet.

My theories: IACV valve got damaged or is sticking for some reason or I got excessive air in the coolant system. My battery is now disconnected and I'll try and take things apart again to check the IACV. Probably bleed the cooling system.

Any other thoughts? As a last resort, I might just replace the IACV.

Thanks for the help

jl03CLS

i had to replace my iacv the first time i took off my manifold to put on the p2r img and tb spacer. same symptoms as you when it first happened.

typeR

its a vacuum leak somewhere check everything top of upper inake that gasket is easy to put back on upside down

CL-S progression 01

iTrader: (2)

IACV are picky lil bitches!!! I learnt that from my damn ford probe! Cleaned out my bro's IAC on the 97 prelude, cause i was installing the skunk 2 manifold and thought why not. and same thing. Took months for it to balance out somehow.. and a sea foam just to make sure. lol


1- u sure the gasket is on the right way? It's happened to some ppl and taken them month(s) to realize it was a simple brain fart on their part.

2- vac leak ? Get a hose and put that to ur ear and then move the other end of the hose to where you are looking for a leak. You will DEFINATELY hear the air leak if you find one.

3- lastly I'd have to then blame the friggin IACV

richardparker

iTrader: (7)

definitly sounds like a vac leak.

aznboi2424

iTrader: (10)

or IACV

TarzanCLS

iTrader: (1)

^vac leak
then reset the ECU and if idle problem still persists, go for a short normal drive see if it helps. Air in the coolant system wont give you a funny idle, you'll start overheating.

07HR350Z

It sounds like a vacuum leak but to make sure, put your hands over the area and listen for a sound. If you hear a whistle or the intake sound get better or change from the TB then you have a leak. The bigger the vacuum leak the more violent the rpm's will rise and fall and eventually the ecu will take over and go into limp mode and you will get an erratic rpm that rises to 2500 or so and drop a bit and rise again.

SilverPhoenix

Hey guys,

Thanks for the advice. I took the throttle body apart again, took off the IACV, disconnected the black electrical unit (interesting magnetic rotational valve) and cleaned the thing out again until the valve spun around smoothly. Looked clean as a whistle. Replaced and tightened everything down snuggly to specs, but the engine still initially revved high at first (~1500-2000) then when I hit the gas started doing that up and down crap. What a headache!

I'll try looking for a vacuum leak tomorrow once I'm out of work. I've been extremely careful to carefully tighten all the hoses, and I'm quite sure that I placed the gasket on correctly. Easily changeable - I'll try flipping the upper gasket to be sure.

My intake sound is quite loud, so yall just cup your hands and look for changes in pitch? A vacuum leak sounds plausible.

And my last solution is the IACV. I called Autozone and they told me that there's a Duralast brand that is only 89.99! Isn't that quite cheap compared to the $120-140.00 ones I'm seeing elsewhere on the site? Any one try this brand?

civicdrivr

iTrader: (9)

Yes, and no.

The IACV is a very picky beast. If alittle bit of air gets trapped in the coolant passages in it, it will receive incorrect readings causing interesting idle issues.

Ive still yet to fix my idle issue since swapping intake manifolds. Even swapping back to the old manifold didnt fix it. I know its not a vacuum leak, and Ive tried 2 brand new IACVs. Ive tested all the wiring and it all checks out alright. I ended up "tricking" the ecu as a temporary fix. Hopefully you can get yours settled correctly.

BTW, if you reset the ECU, did you do the idle learn procedure?

kyle77777

I would just replace the IACV. When i had to replace mine it looked very clean but was still faulty. Make sure you reset the ECU like someone said before

fsttyms1

Easiest way to detect a vac leak take some TB cleaner and spray it around the TB. If there is a leak the idle should change.

civicdrivr

iTrader: (9)

^^ Yup

And if you want to verify if its the IACV, removed the intake tube, start the car up and place your finger over the port on the bottom of the TB. If the idle changes, then its your IACV, if not, look elsewhere.

CL-S progression 01

iTrader: (2)

wait.. when u gas it, the car goes all wonky? that don't sound like a IACV then. I'd have to point at Manifold gasket unfortunately..

vac leak won't make sparatic revs when u on the gas (I.E up and down 100s of revs) at least from my experience, it'll increase idle and usually is fairly subtle in the up and down rpm movement. Bad IACV.. = all sorts of weird idle characteristics, but not when u on the gas.

When you say hit the gas do you mean just a little or what? and u say rpms go up and down... can you explain from where to where and fast or slow. That'd really help

I'd do what civicdrivr told U to do to the throttle body to void out the IACV. if it passes the test and works... take the manifold off and I'm betting it's backwards.

I know you prolly don't wanna believe you caused the problem, but hey.... we all make mistakes.

Just be thankful it takes like 20 mins to pop that manifold off.

FYI when I did my manifold gasket I simply unbolted the TB, and left everything all connected. then detached the hoses on the back of the manifold and cable on the left side on the manifold and ur DONE.

That's also how I installed my plenums. and I got the gasket a week later so I undid the manifold all over again... etc.

So it works and it save a SHIT LOAD OF TIME.

Seems to me like the egr may be blocked (that is what happens when the manifold gasket is upside down.)

SilverPhoenix

Alright guys, thanks a bunch for your input. It's raining like a biatch right now in Seattle and I just got back from work, so I'll get everything worked on tomorrow.

There are two gaskets, right? The one from to top of the intake manifold and the one where the intake manifold comes down to rest on the block?

And in terms of the revving details: I started the car the other day several times and the idle started off a bit high in neutral (>1000rpm, I think around 1500rpm). When I gently pressed on the gas, the revs would slowly increase as expected, then when I let go the revs would rise and fall repeatedly over a span of about 1000rpm.

I'll try swapping the upper gasket (easily changed since you just take off that cover), then I'll take the entire intake manifold out and flip the gasket.

I'll search for the vacuum leak afterwards then at last resort, just change the IACV. Damn, what a headache! Especially when I'm workin frickin 10-12 hours a day with this damn problem!

CL-S progression 01

iTrader: (2)

headache or not you will find and solve this problem and have a damn good week because of it :-)

SilverPhoenix

So I tried plugging the hole to the IACV with the engine on. No change in the RPM changes - still over a range of 1000 RPM from 1500-2500 RPM.

I used an old vacuum hose to listen to the engine and couldn't really hear any leak near the throttle body. It's all loud so kinda hard to tell. But I did hear the revving noise louder near the intake manifold (but then again, I'm closer to the engine). Am I supposed to hear a high pitched whistle if there is a leak?

I took apart the intake manifold again and don't think that I flipped the upper gasket upside-down - there are etched carbon marks from the pattern of the upper plate cover, so I'm sure I put it in correctly.

There is no way I flipped the lower gasket to the upper manifold, since there is only one hole for the EGR and no way to flip it without completely missing the holes on the gasket.

What I did find, however, was a possibly "broken" gasket. It appears that the gasket is metallic and built in three pressed layers. I forgot to tell yall that I accidentally overtorqued a bolt the first time (Autozone gave me a wrench with too high a torque rating and dialed below what the wrench was calibrated). Anyway, no damage to the manifold or lower engine, just a broken bolt. Anyway, the gasket layers are now split and not pressed anymore (ie. not one pressed layer but now three layers).

Do yall think that this could explain a vacuum leak? I'm gonna bring it over to the parts store and possibly order a new gasket first. Then I'll replace the IACV if there's no other explanation.

Thoughts?

CL-S progression 01

iTrader: (2)

ok u sure u didn't switch a connector around??? sounds stupid i kno but still ver poissible??

and I think it is possible to put the gasket on wrong if it's 180degress and upsidedown.

I may be mistaken tho

civicdrivr

iTrader: (9)

If you plugged the whole for the IACV and the idle didnt change, its not your IACV.

Were you able to get your trouble codes read? Those issues also sound like the Throttle Position Sensor may be misadjusted or broken. Did you remove it from the throttle body during cleaning?

CL-S progression 01

iTrader: (2)

yea that's what I was thinking, which is why i asked if the switches may have been reversed. I'd seriously look into a tps issue.

SilverPhoenix

So I replaced the IACV and damn, still having the idle issues. Still keeps revving up and down between 750 and 1500, when I come to an idle. Otherwise, the car pulls nicely and things seem much smoother after I cleaned up my throttle body and EGR.

I did spray some throttle body cleaner around the engine and noticed that the idle changed (started revving with less range and started kinda bouncing up and down) and then the engine light came on. I took the upper gasket off and made sure everything was installed correctly, then did a battery reset, which cleared the engine light. But still, the same issue.

So I took a vaccuum hose to the engine and I really think that I'm hearing a faint high pitched whooshing noise near the left back side of the engine block. Since I had an issue previously with my manifold bolt, I think that maybe I have a gasket issue. So I ordered a new manifold gasket.

Other than that, anybody else have any thoughts? But since the light came on and idle changed when I sprayed the throttle body cleaner about, I'm assuming that I have a vacuum leak.

CL-S progression 01

iTrader: (2)

once u get that gasket... put in on, tighten everything up evenly, both top and bottom manifold gaskets. Make sure you aren't losing air through the plenums where they snug up to the manifold and where they attach to the back of the rear plenums (the 4 hoses).

You really gotta be meticulous at this point to rule things out so you can look elsewhere. So take some deep breaths and think/do it slowly so there are no ifs ands or buts. This will ensure you know there are no vaccume leaks. What about the tb gasket hows that POS look? they are paper thin.

so then if there's no vac leak (which there probably is) then I'd have to look at the tps and the connections. Maybe a wire isn't in the connector properly causing bad readings.

You'll have to think outside the box if it aint a vac leak. something near what you touched that took a dump at the same time you tinkered with the car.

FYI this shit can happen even though i still do not believe in Irony.
just re-arranging something sometimes is all it needs to kick the dust.

civicdrivr

iTrader: (9)

BTW, if you swapped connectors for the IACV/TPS the car wouldnt run.

Try the new gasket, torque everything down to factory specs and in the correct sequence. Dont over-tighten.