ATk's Stroker Idleing at 4000rpm's Help!

[Russ_93yj]

This is my first stroker but not my first motor replacement. This motor had much more X factors and has been fun. I need some help to get it right. With the My 93" Wrangler being so old I replaced most wearable parts like gaskets, hoses and so on.
Here's what I've got or replaced.
Atk 4.7
99 intake
63mm TB + 1" spacer
Stock 93' injectors (will replace with some 24's) @ 30psi
Adjustable Fuel Pressure
Borla Header
Stock Ignition Advanced
ATF Gauge
Repaced Parts:
O2 Sensor
AIS
CPS
Coil
Cap
Rotor
Wire
Vacume Lines
I'm thinking of replacing the MAP sensor today although the ATF mixture shows to be correct and the TPS. I have a OB1 scanner and nothing comes up. I have also discoed the PCM. To ensure there are no vacuum leaks I have plugged all hose's except Fuel Pressure and MAP sensor. I also reinstalled the intake with a new gasket, used red rtv as a sealer and then tortured from the middle out.
This high idle isn't my ideal way to break in my new motor

[coas]

Start with installing stock size throttle body and stock IAC.

[SilverXJ]

Throttle body size wouldn't be the problem. A stuck open IAC could be. It really does sound like you have a massive intake air leak someplace. I would plug off all vacuum lines on the intake and check your seals between the throttle body, spacer and spacer and intake.

[coas]

Throttle body size wouldn't unless a poor job was done on matching the plate.

[Russ_93yj]

I just got back from NAPA and got vacuum plugs a MAP sensor and a TPS. I have plugged all the vacuum ports except the fuel pressure regulator, MAP sensor and brake booster.

I had my original TB machined by Leigh Performance Machine to the 63mm, who I also got the spacer from. The gaskets are new and no whistling sounds, so I assumed the install was good. I can double check my install.

As soon as I can get my optima off the trickle I will try staring the motor with the AIS removed. I read that this can help single out the AIS as a cause and drop the idle at the same time.

[UncleWally]

If your idle was a little lower, you could use carb cleaner to find vacuum leaks. I'm thinking at 4k rpm and this would be worthless as you look for a jump in rpm when you spray the carb cleaner. It more than likely wouldn't be very noticeable at this rpm.

Brian

[Russ_93yj]

Well as Brain expected the quick start was a wast of time.
I replaced the TPS and the MAP with no improvement.
With the AIS removed the rpm's went up so I put it back on.
While it was screaming away for no reason at all I unpluged a small vaccum line that T'd with the MAP sensor and the rpm's droped to 1500. This makes no sense to me at all any Idea's
I keep tinkering on it and checking in Thanks guys!

[the_wrench116]

Start with installing stock size throttle body and stock IAC.

i agree with this and also plug the brake booster hose. its a big hose and the brake booster diaphragm die once in a while. as far as sealing the intake to the head i use copper rtv, grade 8 hardware, and lock washers cause all but 2 of my studs kept backing out. good luck. also is the air filter on or can you look in to see whats going on when you start it.

[1bolt]

Good lord 4000 RPM's is basically unthrottled... there should be a very obvious sucking chest wound (so to speak)... So making a vac leak caused lower idle? Well what does that tell us -- if anything? That lower vacuum in the manifold lowers the problem... I like the brake diaphragm hypothesis, however unplugging a vac line at idle on a correctly functioning engine usually just raises the idle a little and makes it run rougher (due mostly to disparity between what the TPS sees and how much air is getting in causing lean mixture)... if lowering manifold vacuum (via causing a leak) reduces the problem then the problem should be something that relies on vac as it's signal or trigger... Not sure how the brake booster would cause the problem in such a way that an intentional manifold vac leak would lessen it... If the brake booster was the problem the leak you created should have had no effect other than raising idle a bit more not lowering it...

What about the evap canister? it is both under Vacuum, and vacuum triggered/operated... I seem to remember an old symptom of the 4.2 YJ's charcoal canister when they went bad it would cause the engine to idle very high... Could be misremembering though...

[Russ_93yj]

I would never think of the canister being a cause of all this headache but I up for anything right now.
My tach started to drop out and not read the rpm's.
Todays plan of attack is to plug all vacuum ports and start added them one at a time with the canister being last. The last sensor to replace is the CPS to address the tach.

If I run stock 93 injectors with a 99 intake is a MAP adjuster necessary? I have one for when I put the larger injectors in.

Thanks for the help so far

[lafrad]

To put it simply: you need air for horsepower.

At idle, that means you need air for higher RPM.

The map sensor has no real control over airflow. It detects how much air pressure is in the manifold, and allows the computer to adjust fuel accordingly. I would venture to guess that unplugging the MAP actually just runs the engine really lean or rich, which drops the rpm due to poor combustion efficiency.

The computer adjusts the Idle Air Control motor based on if the RPM is close to the desired Idle rpm, or not. when its cold, and or when other load factors kick in (A/C, etc) it bumps the idle speed up and down... but its always adjusting that based on how close the idle rpm matches the actual RPM.

4000 rpm is a LOT of airflow for idle on one of these, especially a NEW engine that hasn't been fully broken in.I would look for a rolled Intake manifold gasket, a hole/crack in the intake manifold, or a bent throttle body part (either the blade or the shaft).

Also, make sure your throttle pedal in the truck isn't stuck on anything, and that it moves freely and appropriately (just disconnect it and the cruise control from the TB completely. the truck should start with only the IAC motor doing what it needs to do)

[Russ_93yj]

So far today I cleaned the dizzy and replaced the CPS (only 6 months old) because I'm running out of sensors to replace. No change.

The good news is that I put on the MAP adjuster, unplugged the charcoal canister and the idle no longer jumps goes to 4000, feeww. I plan to leave the can unplugged until I break in the motor a little more.
Now it goes up to 2500 for a short time (AIS) then backs down to about 800. Then a pulse start between 800 and 2000 rpm's. I know common sense leans towards vacuum leak and I would agree if my tach wasn't acting up. I still have no engine light but I am beginning to suspect the PCM. All the other gauges work and as I understand it the route of info for the tach is: CPS-PCM-TACH

I have replaced the intake/exhaust gasket using a small amount of red rtv as a sealer. I'm running the TB with out a air cleaner for now in a clean warehouse. The linkage has slack, no Cruise Control, when I look down through the TB it's a strait shot and evenly spaced. The gaskets are a bit on the thin side so I cut some new one's in-front of the TV tonight. The blade on the TB close's the mouth 99%. I was pretty excited when I got it and was playing with it making monster truck noises for like 15 minutes.

To single out 99 intake as the problem I could put the oem intake on but they suck

[gradon]

There are clearance issues with some Borlas and 99+ intake. If you take a card and try to put it between the top of the #5 exhaust primary and the bottom of the intake manifold, you might see that the card won't fit, cause the mani is resting on the Borla--the intake is not sealed on the head. Take a sharpie and mark both. Remove manifold and grind a little on the bottom of the intake and take a ball-peen hammer and bang in the Borla a 1/4" or so.

[1bolt]

Well looks like the evap can was your major vac leak! At least you eliminated that problem. Did you plug the IAC back in? That could possibly be why your idle is wandering around. Now that the major vac leak is known, go back through and make 100% sure you've actually got everything hooked up right and plugged back in from your trouble shooting. It's very easy in the course of trying a dozen different things and replacing sensors etc -- to leave some things loose, unadjusted or unplugged. Especially vac lines!

Replace your Evap canister then start from scratch, check and double check all vac lines, plugs and sensors that you may have disturbed at all. Then reboot your ECU (disconnect neg and pos and then touch the pos to the engine for 15 seconds so the capacitors will be discharged... Then turn your key on then off 3 times before hooking the battery back up. Just for certainty I usually turn the key off/on with the pos terminal grounded to the chassis and leave it on for a while --go get lunch or a Beer -- just to make sure that the non volatile memory is erased. I think the key on/off sequence is mostly to eliminate any chance of capacitors in the ignition on side of the dash electronics from trickling electricity back to the ECU but i could be wrong. Anyway the factory instructions for clearing the computer include the key sequence.

[edit] Oh yeah good catch Gradon; if you have a 99+ intake and a Borla there could be interference, which would cause all sorts of leaking to happen... But this shouldn't be changed by unplugging the evap can or making a vac leak...

[Russ_93yj]

Oh another great catch! Number 5 is all pushed into the intake. I can't wait to rip that sucker off and do it right. Doe's anyone know if the Banks torquer have the same issue? Please let this be the last of it, I should have been in the mountains by now. I'm going to try to skip off work early