RB25 SII: High Idle after Plenum Install

[KoshiLe]

GReddy Plenum bolted on with FMIC and Q45 tb, Series II RB25DET with Greddy emanage ultimate

What i've done.1. extended 2 sensors2. hooked up AAC to charge pipe3. Re-scaled TPS 0-100% on emanage Ultimate (this confirms iam using the right sensor and getting TPS signal)4. Checked for vac leaks by spraying parts cleaner5. made sure Q45 TB is completely closed6. checked for FMIC leaks7. Adjusted AAC valve screw all the way IN and OUT

Problem:It still freaking idles at 2000 rpm.

Please give me no BS about searching.. bc i have been for over a month and no one responds or has come up with a solution.

[Cjmartz2k]

Check for leaks using a pressure tester (boost leak checker) not carb cleaner. New intake install + high idle = vacuum leak 99.999% of the time.

[KoshiLe]

I will try that.

I just try adjusting the TPS sensor by loosening those two screws and turning the sensor a bit... it effects the idle but not enough to have a good idle.

[KoshiLe]

Just tried rewiring the TPS a few different way, and adjusting idle screw again.. with the RB25 method.. (warm engine, disconnect TPS, adjust idle, then reconnect TPS) no luck either.

[rb25det250sx]

my guess it vac leak... but i would also check ignition timing.

[robbie2883]

just asking the obvious here, but you don't have the throttle cable too tight do you?

[b00stinbmx]

did u take out the idle control part of the q45 activated by the coolant lines?

[KoshiLe]

cold idle springs removed from Q45 tb, sorry forgot to mention, it helped temporarily before this... previously it was at 1500... nothing's changed and now its almost 3000 rpm!

TB cable is adjusted perfectly, i also adjusted taht little screw on the bottom side so that the butterfly is completely closed when iam off the gas.

I dont understand how timing could be bad when i never touched it.

What i feel might the problem.. is a combination of a VAC leak AND a bad injector o-ring, leading to more air and fuel coming in = higher idle.

But i will check Ignition, o-rings, and vac again tomrrow when i rip my bumper off.

thank you all for your help!

edit: What do yo think about removing AAC set up all together? And just adjusting butterfly to a good gap?

[Joe]

for like the 8th time, its a vacuum leak. check your vacuum lines also the manifold gaskets. if you didnt clean the head/manifold 100% perfect or torqued it in the wrong sequence you can have a leak at the gasket.

[KoshiLe]

okay i will remove the manifold and have it remachined for safe measure and maybe a skim coat of RTV and report back.

does anyone know correct vaccum nipple size and thread pitch? Iam going to replace just incase.

[bkos90]

check if the injectors are sealed... i had a vac leak because one of the injectors was not sitting correctly in the seal.

[KoshiLe]

check if the injectors are sealed... i had a vac leak because one of the injectors was not sitting correctly in the seal.

hmm good point. I got my injector harness pointing up and when i installed. i Greased the orings before gently pushing them in.. and wen the slid in.. it popped into place. sounds right?

[Cjmartz2k]

Yes, it sounds right, but your just guess all of this stuff is good. Take 10 minutes, make a boost leak checker, attach it to the throttle body and test it. Eliminate that as a possible problem and go from there.

[KoshiLe]

Hey peeps, coming back for an update.

Tested Manifold AND intake piping using a coupler connected to a boost leak detector (regulator and gauge) to see if it leaks anywhere. I found zero leaks.

As for timing, i used a timing light and noticed the timing was SEVERELY advanced. I dont understand how any of this could change doing the plenum, besides the aac valve causing it to fluctuate slightly. So what i did was

1. readjust TPS to get down rpm as low as possible and lock it back down.

1a. checked injectors for broken o-rings, found one worn so i replaced it, and tightened rail down pretty damn tight.

2. rescaled TPS range on EMang Ulti

3. Turned AAC idle screw all the way in (brought it down to 2000.

4. adjusted injector delay (again, i dont understand how this could effect my idle) brought idle down to 1500 rpm.

5. Unplugged AAC, Turned CAS clock wise all the way.. (not sure if this is a good thing, but idle timing is correct now) and it idles at 900 rpm with A/C off. Then reconnected AAC and it works.

I know it is not safe to drive the in the state it is now, but it will be getting tuned this week.

My question is... should i have turned the CAS that much just to get it to idle? Or is this a sign of other issues? Compression is 180 psi flat across.

[SullivanRacing06]

or you didnt install a the im gasket correctly or at all, vac leak

[OBTRICE]

He just said he did a pressure test and found no leaks.

[Joe]

yea somehow i doubt he pressure tested the manifold

how did he close the intake valves so air wouldnt escape?

[d356bud]

did u remove the air regulator on the Q45 tb?

[KoshiLe]

did u remove the air regulator on the Q45 tb?

Yeah, If you're referring to the cold start coolant solenoid.

I had a tech friend set it on compression stroke, then tested. After the manifold.. i did it on my hot pipe from turbo outlet. I had Air regulated at 22 psi coming in, after it charged.. i watched the gauge to see how fast it was going down.

on the Q45, i adjusted 3 things.

1. Removed Cold start coolant solenoid

2. There's a tiny little screw with a lock nut on the bottom (if installed on RB25) that the butterfly level bumps to keep it slightly cracked or can be adjusted so its neutral position is completely closed. I adjusted it to a slight crack after i got my car running bc i removed my AAC.

3. Adjusted the TPS Sensor back a little bit until it read .4 v at new "closed" position.

Iam not sure why this all came up, but i do have a feeling it has to do with the fact i have a series II rb25, i removed the TCS harness on stock tb, and only used TPS. So i guess there is no "idle verification signal?"

[KoshiLe]

The adjusting screw ontop... i turned the whole sensor back about 2 mm

Front of the screw that throttle sits on when you're not on the gas, I adjusted it just enough to keep idle.

Red circle - Factory RB25 TPS signal, Thick red wire is insulated and is the center pin on Q45 TB

Blue circle - factory traction control, as you can see i didnt use it.

[Joe]

I had a tech friend set it on compression stroke, then tested. After the manifold.. i did it on my hot pipe from turbo outlet. I had Air regulated at 22 psi coming in, after it charged.. i watched the gauge to see how fast it was going down.

what?

you cant set all 6 cylinders to the compression stroke at the same time.

AN INTAKE MANIFOLD GASKET IS LEAKING. go buy a bottle of brake cleaner. spray it on the gaskets. top, bottom, sides, etc. listen for the idle to change.

[KoshiLe]

go buy a bottle of brake cleaner. spray it on the gaskets.

Man i went through like 2 bottles. Had the car running in the air to spray the bottom of the manifold. Only leak i can hear is right inside the TPS, if you can see where its cracked. I sprayed the crap out of it but it doesnt change the idle.

Someone told me to try soapy water and look for bubbles... not sure if that is wise.

[Joe]

if you can hear air at the TPS why havent you fixed it? you arent supposed to hear air, ANYWHERE.

[KoshiLe]

if you can hear air at the TPS why havent you fixed it? you arent supposed to hear air, ANYWHERE.

Because it hasnt effect the idle or performance. I spray it nothing happens, it makes a slight puff when you stab the pedal. Nearly filled the thing with cleaner and nothing changed.

Im going to put it on the dyno in the next few days, maybe that will show something? Like boost dropping off to confirm there is a leak somewhere.

Just did the GM boost solenoid mod, so i THINK higher cycling to hold boost will confirm a leak? Since my search has shown nothing.

[eh?]

Is your rb25 air regulator powered and closing?

[meet07]

Not sure how you checked for vacuum leaks but this is how I did mine thanks to Cjmartz2k

I took out my old harbor freight $99.00 dollar welder, 2.5 inch steel pipe that was left over from my turbo integra that I capped off and drilled a hole in, and a female quick connect for air tools. I had all ready had a qucik connect device made from years ago that has a ball valve on it and a gauge that read up to like 200 or something.

I also rigged up a squirt bottle that had some car wash fluid mixed with water. I shook it up really good.

-I hooked my little contraption to the intake of the turbo-cracked the ball valve to maintain about 20psi-sprayed the fluid every where that a leak could possible develope.

When i did this I found leaks everywhere but I didnt have high idle so...

here is the contraption:

[Joe]

boost leaks are waaaaay different than vacuum leaks guys.

[KoshiLe]

what i did was hook up a air hose thats regulated to my TB... charged it to like 7 psi or more, put my car on "ON" position and see if Map sensor reads the same if at all.

Not sure where ill get with any of this, but my idle is normal, hopefully my performance will be. I dont see too many SII doing this mod that has issues.