1250b18c5

...so here it goes:
1)B16 running obd 1 on a Pherable dot net ECU, NO codes,runs flawless except for the following...
2) Fluctuating idle...1000 to 1500/1800 rpm ALLL the time once warmed up, although while slipping clutch, can lower idle to propper steady 750-800 rpm, but once at the next stop, fluctuating idle continue's again.
3) Replaced intake manifold gasket, as well as TB gasket.
4) Replaced fuel injector base seals as a leak was found at the base of injectors using ether...aka liquid fire.
5) Have totally replaced now FIVE FITV's, AND FIVE IACV's,that were ALL either KNOWN good in previous cars OR were BNIB from Honda, $$$$$, WITH gaskets to NO avail.
6) Adjusted timing to 16 degrees.
7) Have bled air, and coolant from drain vent **** on thermostat housing/front of cyl head every time FITV's and IAC's were installed...also NO AVAIL.
8) Adjusted base idle at idle screw on TB numerous times.
9) Also totally replaced TB housing too with newer GS-R model with MAP on top...NO change.

ANy options....looks to me, and from memory as though EVERYTHING has been done....also this is the second car with this complete swap, that this idle continues to fluctuate with....I'm at a total Loss!, and I'm VERY frustrated that with ALL the above, Nothing has ever changed with regards to this iussue!

theYBLEGAL

Try bleeding the coolant by running the engine from cold to temp with the radiator cap loose. On just enough it isnt splashing everywhere. But a few drips are normal. Sometimes bleeding with the bleed screw doesn't get all of it and some bubbles remain trapped.

Your dealing with the fast idle thermo valve, or FITV, the main culprit of hunting idle if you've cleaned everything else. Make sure the TPS is .45v closed throttle, if you haven't already, but I'm doubting that helps.

If anything, try the FITV bypass trick. Then you never have to deal with it again. I live right by chicago, so I see sub-degree weather and 100 degree weather. The bypass has never adversely affected how it runs, no throttle stick or low idle. Even hondata say you can try it, see their guide: http://www.hondata.com/manuals/heats...eatshield.html (bottom)

Good luck!

theYBLEGAL

O and make sure you have the PCV system hooked up properly. Having no PCV and not tuning for the difference will cause havok with the idle system. The PCV valve is a metered air leak and a must

Izo

Ron likes a well labeled thread - 'B16 - idle issues' or something ;-)

1250b18c5

Ya.....I see too....I think he's a mod as well.....he actually changed quite abit....but the gist is the same, and as long as he has some concrete suggestions it's all good.....to theYblegal.....FITV has been cleaned AND Replaced with OEM BNIB fitv's to NO avail as mentioned, and the PCV is Also currently OEM BNIB......all been done!, although I haven't tried THAT particular bleeding process.

Former User

You recognize my love of a good thread title -- title edited. Thanks.

OP:

Step 1 -- When the idle is surging, remove the air intake and use your finger to cover the hole in the throttle body leading either to the FITV or to the IACV. Does covering one of the holes stop the surging idle?

1250b18c5

In light of the OP, with ALL that has been done.....NO, I have Not tried this yet, and Will. Thanks Ron.

I gotta get'er out of the garage, likely later this week, and get'er to normal operating temp, then THIS will be the first thing I'll try, then I'll respond. Thanks very much Ron.

1250b18c5

Well Ron....10 minutes ago I went out for perhaps my "second" little top of fourth and into 5th RP for this summer of 2011.....FUN, FUN, FUN!!!!!, needless to say, got the B16 NOICE and Hot.....once again the old 1000 to 1500 rpm fluctuating idle, and then I took the intake off, and covered the hole.....what'da ya know....PERFECT 750 rpm steady idle....unplug my finger from the hole...back to bouncing idle....and every time thereafter.....looks like I may be into my SIXTH OEM BNIB IAC valve.....let me know what you think.

But plugging the hole instantly fixed the idle.....let go of the hole...back to bouncing.....


there you have it.

Former User

Just to verify. You covered the hole leading to the IACV and the surge stopped, right? Covering the hole to the FITV had no effect?

1250b18c5

YUP.....actually it's an OBD 2 GS-R 60mm throttle body.....only has ONE hole......but yes, when I covered the one and only hole my current throttle body has, YES, the surging Stopped.

here...I'll send/post a pic of my current throttle body opening.....

Paul

Former User

If you unplug the ECT sensor, does the idle surge stop?

1250b18c5

Here's the TB just for verification:




This setup was just doing 135 miles per hour with NO MIL's/CEL's and PLENTY of strong reliable VTAK only 35 minutes ago.


ECT? Please elaborate...Sorry

1250b18c5

BTW Ron....warm-up idle IS flawless with NO surging. This is a warm/hot idle issue only. And yes, when that one hole in the TB is covered the surging stops.

Former User

Locate the 2-wire ECT sensor and unplug it. It should have a Grn/Wht wire and a Red/Wht wire. Does this stop the idle surging?

1250b18c5

thanks/sorry for the clarification....I'll try this next. And have never tried this previously......I was kind of thinking you were going to aim me in the direction of IACV replacement due to the symptom disappearing when the hole on the TB was blocked.

I'll try this next.

thanks

Former User

If unplugging the ECT sensor doesn't help, next try unplugging the O2 sensor to see whether the surging stops.

1250b18c5

K....I'll try both of these and get back to you....I gotta go back out and run the car again....getting late here in my time zone and the 15 month old and the 4 year old boys are in bed....right above the garage.....!LOL

I'll get back to you with the results of pulling these sensors.

Thanks Ron

1250b18c5

Hey RonJ.....September 26th.

Just got back moments ago from trying your suggestions, plus a few others.....

1) Unplug ECT....NO change, just a fresh CEL/MIL, STILL surging idle.
2) Unplug IAT.....just for kicks....NO Change, another fresh CEL/MIL, STILL surging idle.
3) Unplug O2....NO Chnage, just yest another CEL/MIL for O2, STILL surging idle.

My idea...
4) Unplug FITV....Perfect idle, but also fresh CEL/MIL for FITV...and when plugged back in before clearing codes, idle surges again but now REALLY Fast!
5) Plug the above pictured TB passage/hole and idle is PERFECT like unplugging FITV, with NO CEL/MIL.

It should be noted that after each attempt at unpluggin sensors, the then placed code was erased, and each time a different sensor or actuator was unplugged it was with a clean slate as for as the ECM was concerned.

So there you have it Ron.

Any suggestions....ie: try yet ANOTHER BNIB OEM FITV or IAC.....$$$$$$$$$, hopefully not....I'll just try FITV's or IAC that were taken directly off of known smooth/perfect idling cars.....looking forward to your input.



Paul

Former User

Does your FITV have an electrical connector? Most do not. Post a picture of your FITV and its plug.

Have you also tried unplugging the TPS sensor?

1250b18c5

YOUR absolutely right Ron, I'm TOTALLY wrong....and I knew as soon as I read your response asking for a pic of the FITV....here they are....blurry...camera won't focus that close to a subject....

FITV:


IACV:


Sorry Ron...so in the last reponse, I mentioned I unplugged the "FITV", I MEANT the IACV....when the IACV was unplugged the idle was perfect, yet it set a code/CEL/MIL for missing IACV, and when plugged back in the idle surged quickly.

I haven't tried the TPS yet....but that TB is almost as new, and the car has idled this way with both previous TB's and the newer 58mm GS-R TB...

I guess I could try again with the TPS and get back to you....I honestly think pulling the TPS connector will have the same null effect as pulling the IAT, O2, and ECT like earlier today. I've tested the TPS and it has the .45v at the specified requirement, closed and almost 5v at WOT.



Thanks again Ron...I'll try the TPS next and get back to you.

Former User

I understand what you are saying about the TPS, but give it a shot to cover the bases.

Have you bled the cooling system? If so, what was your method?

Have you also tried to adjust the idle speed? If so, what was your method?

What resistance do you measure across the two terminals of the unplugged IACV?

Have you tried a different ECU?

theYBLEGAL

Turn the idle set screw to the right, so that it is about a 1/4 turn back from being completely screwed in. sounds like you've just got too much air entering.

warm up idle is supposed to be high, so the extra air is ok. once the ecu wants to bring the idle down due to warm enough coolant temperature, it discovers that the iacv can't compensate for the amount of extra air.

also, you don't have a fast idle thermo valve, the fitv. you just have coolant lines running there to keep the throttle from icing over in extreme cold. in the midwest here, i've bypassed that with no issues. it keeps the intake air temp lower like i said before.

try downloading the honda factory service manual available all around the internet in PDF form. the 96-2000 manual and the sections pertaining to the b16 and cooling should help you out. just follow the directions