Initial start up 5000 rpm idle then Bouncing rpms
 

Hello everyone

I just built a 6 port turbo motor

* N/a s4 rotors
* JDM turbo 2 uim and lim
* N370 Rtek version 2 Ecu
* 550cc primary and secondary fuel injectors
* Stock s5 Turbo
* Stock ports
* All emissions have been removed
* BAC is still being used. right now all nipples/ports on the bac are capped off.

Just so you know at no time the below happens i press the gas pedal

When I start the car Rpms automatically rev up to 5000 rpm and sometimes higher, it will hold that rpm for 15 seconds or so then drop down to around 700 rpm then consistenly bounce from 1000 rpm to 2000 rpm, and this is where it stays idling intill i finally turn car off.

I have disabled the AWS output in ecu but still revs very High, and AFRs are around 13.6 - 13.9.

Have already set timing also.

I am under the impression the items to look at are

* possible bad rotor? Note I will attach a video showing what the car is doing, from the sound of idle i do not think this is the problem, motor sounds healthy . checked compression yesterday on back rotor and compression was around 70 psi, is this ok since motor is new still?

* Water thermosensor faulty
* TPS adjustment


I will send a video showing what the car sounds like when idling, I remember before the car when N/a would bounce when idling also but not for this long.

Any help is appreciated.


Chino

the .mp4 file shows a brief video of the car idling with the bouncing idle.

Until you host the file somewhere other than your C: drive, it don't show nuttin.

ill try using dropbox

https://www.dropbox.com/s/safi88gjk3...25600.mp4?dl=0


Hopefully this one works

You're making this too hard on us...I ain't creating an account or signing in to see your vid.
Get on Photobucket or something like it.

im not making this hard on anyone on purpose i usually never have to upload anything im not use to doing this, i will make a photobucket account

Good.

Now I hope I have something substantive to say when the vid appears...

http://s722.photobucket.com/user/rot...4.html?filters[user]=143303855&filters[recent]=1&sort=1&o=0

This link is with Photo bucket,

haha........ I do to. do you have a 6 port turbo? or from the description what is your opinion on issue?

Initial start up 5000 rpm idle then Bouncing rpms
 

my first thought is, did you remove the thermowax? is it way out've adjustment? i don't think your bouncy idle and high RPM issue are the same problem. with your bouncy idle i'd say vacuum leak for sure somewhere, or your tune for the rtek is way off

try this, get a buddy, have them start the car while you hold the throttle body fully shut and see if it still screams at startup

Yes the thermowax was removed before i purchased the JDM manifolds, I verified the TPS narrow range was 1K and Wide range is between 1k - 5k ohms i will check again when i get off.

I will check again for vacuum leak so far everything i checked is secure.

yesterday i removed throttle cable completely from throttle body and made sure throttle was closed completely but i will try what you mentioned also.

from the video does it sound like one of the rotors isnt firing? i checked spark plugs (just trailing) and they were clean with no black or tan color to them.

Thank You for the information.

Hey everyone have a update, looks like the problem with the 5000k rpm idle is taken care of at least. I checked the ohms of the TPS (narrowband ) and it was at 0.990 ohms i adjusted to 1000k, but idle still went to 5000 rpm, so i hooked up the palm pilot to the ecu and checked the tps % and it was at 18 - 20%. just to see if it made a difference i adjusted the tps intill the tps reading from the rtek showed 0% ( the lowest i could get it was 4%). I tried starting again and finally the high revving stopped. so im looking for another tps just to verify it is not faulty. The idle still bounces around 2000 rpm but after work ill check for vacuum leaks.

iduley you were right the issues werent dealing with same thing and right now im going to have to agree with you on the Rtek tune, i think i am going to use factory map for initial start up to see if this helps the bouncing idle and verify no vacuum leaks. i think this will give some good information on whats going on. the motor seems strong just idle is muffed up.

Initial start up 5000 rpm idle then Bouncing rpms
 

what other tune are you using other than the stock base map? only other thing i would try is using the turbo maps, and maybe just bump up the fuel a touch being your using n/a rotors, than use your wideband (if you have one) and adjust the idle AFRs wjere they need to be, BUT, if you can't get it to stop loping no matter what tune you use, you'll never get the AFRs set correctly

just the stock turbo 2 maps, right now I have 15% fuel increase then I was going to decrease depending on the AFR readings. I have a PLX wideband hooked up now at this point the afrs are 13.6 - 13.9.

im off on the weekends so ill have more time to work on this before getting to late out, Im excited about getting the car running again.........but no one else in the neighbor hood is lol

Yesterday I set the TPS this time by voltage instead of resistance, After verifying the tps was adjusted to 1 volt i started car (first time started the whole day so motor was not warmed up at all).....car idled awesome but after a few seconds the hunting/bouncing idle starts again (after motor gets warm it seems like i can never get the idle to stay consistent like the initial first start up of the day). this is leading me to believe there is another sensor that is possibly not functioning correctly during/after the warm up process causing the change in engine operation. i will check voltages of the IAT, AFM and Water temp sensor when i get home.

I checked for vacuum leaks also and did not hear any neither did i see any damaged vacuum lines. I also sprayed some carb cleaner around all vacuum lines and manifold block off plates. there was no difference in idle.

With the JDM manifolds, there is no thermax wax or any type of factory idle assist on this manifold, is it possible there still is a spring that needs to be removed from the throttle body? i read in another thread about possibly the idle spring not being removed after the throttle body mod.

Ive been working on the Fc and so far my idle still bounces but i went ahead and took for a drive, AFRs look good, motor boost with no problems and water temps, everything is fine except the idle,

But i got some new information, i was told due to not having my Auxiliary port sleeves installed what is happening is there is a pressure wave from auxiliary port that is getting back fed from the motor back up into the Intake manifold causing this bouncing idle. with out the sleeves installed this is normal.

Can anyone shed light on these symptoms when sleevs are not installed? i read on rx8 forum about this but i have not stumbled across alot of information regarding this.

the high idle "bounce" is always due to a high idle, either your thermowax isn't adjusted properly, has air in the lines, is stuck or the curb idle on the throttle body has been adjusted up and needs to be set back down.

normally the first test i do is manually open the thermowax cam to see where the warm curb idle is set to and to rule out the thermowax as the cause. you can do this with a screwdriver pressing the cam off the thermowax, basically opening it manually.

I may not be the expert that some of these guys are in this forum, but my car has the bouncing idle sometimes. I believe it has something to do with the thermowax. But my car will stop doing that once warmed up. It usually only does this when it is colder out as well. As far as the high RPM's I would make sure your throttle cable is not sticking at all. Try to pull back on it a little and see if RPM's drop. If that isn't it I would think that you have a vacuum issue as others have stated. One thing I did was take a water hose with the car cold and just started and saturate the area to see if the idle drops when water is in a certain area. This is stopping the air so the idle drops. I also ended up buying a smoke machine and tied that in to my system and it made it east to find the leak.

The throttle body is modded, there is no dashpot or thermowax, i agree but i do not have another manifold i can try, in the above post i got the car to idle correctly for 20 seconds or so before the bouncing idle happens. without the thermowax in place it seems as if there is no fine adjustment to keep correct position of throttle plates.

i know forsure it is not a vacuum leak once the tps screw is adjusted the idle becomes smooth just doesnt stay smooth, if anything throttlebody with the original thermowax setup could solve the whole problem but will need to sorce one without a throttle body mod.

Thanks for the response

as of now the car is driveable i will source a manifold and worry about it then. i noticed after driving i am getting a leak between the rear rotor housing and rear iron, im going to replace the seal tommorow, then ill keep working on the tune and idle issue.

If anyone has a untouched throttle body from a JDM or USDM s5 turbo let me know. I have a turbo s4 throttle body but from what i can see the tps mounting point will not work due to the s4 and s5 tps sensors being different. havent verified 100% yet

that's why there are so many recommendations to leave the idle controls intact, without a functioning BAC or at the very least a thermowax then the car will idle low when cold and high when warm. most of us live with it but we also have standalones that won't give the high idle ignition cut bounce.

honestly i don't even know why it exists in the programming(or why Rtek decided to keep it in their revisions), i have never seen it once manage to pull a car's idle down by doing the purge. about the only thing it does manage to do is warm up the engine about .1 seconds faster than without doing it, which sometimes cures it when the thermowax does finally open if it is set incorrectly or the cooling system has air pockets.

my car for example idles at about 600rpms when stone cold and about 1000 when fully warm(zero idle controls remain), i usually have to hold the throttle down a little bit for about 10-15 seconds before it will even idle on its own when first starting it for the day. you could set the idle to a similar setting to avoid this issue, since the ECU tends to only do the "bounce" above 1100RPMs. some ECUs you can actually map it out so that the car idles the same no matter what temperature, via tuning the timing by temperature and vacuum together(my brick of an ECU, aka the microtech LT8x doesn't offer such advanced features).

that wasent my choice to mod i bought the manifolds like that i agree but thats all i had, this is the reason why i like starting with factory based parts at least when it comes to the manifolds where you run into situations like this, the high idle i took care of, that was due to the tps not being set at 1 volt ( at ecu) and 4% appears on the rtek when watching parameters on palm. i found the air hose for the BAC so i will put the hose back on once i get off.

when you say purge what are you reffering to? the thermowax not adjusting correctly due to the air pocket causing faulty reading? or the airpockets could/also be causing incorrect reading from the thermowax that is located on water pump?

it would be nice if the rtek had adjustment for the idle table but i do not have this option due to not being a s4 ECU. if the tps screw/ idle screw is adjusted as it is being turned you can hear the idle change but it never smooths out this will help keep the lowest rpm bounce point from dropping as low as before the tps adjustment but never completely solves the problem ( as before i could at least get it to idle smooth for a few seconds) BAC and i have another tps that can be tried.

If you were to look at your tps reading on the microtech, does you tps reading show 0% or 4%? 4% is the lowest the current tps installed now will go. Thanks for the response and info