[s5 rx7] stalling while rolling and idling.

[GeenIdee]

Hey guys,
 
I was hoping this problem is familiar with any of you.
 
So i did some thing on my car, used Furb\'s old map on the power FC, ran good untill i went to the dyno at reworx. Since the first or first 2 full throttle pulls it didnt want to idle anymore. And so far i cannot understand what changed that make my engine stall.
 
ANYWAY,
 
We have been trying to get the idle and low rpm ok, and now we run in this next problem what actualy might be the same problem as what started on the dyno but we both cannot understand yet what it is.
 
 
-The driving is good, not fully tuned yet but it drives good.
-Pulling away is ok, it is like it chokes sometimes for a second when i give some gas if its idling. This happens below 1500 rpm, but it can be an adjustment in the ecu.
-and its idling good when the engine is warm, not if its cold.
 
But when i am driving and i push the clutch to make it idle, it will first go to idle speed and then it droppes and the engine stalls. So this also happend when i need to slow down for a traffic light or something, brake, clutch, engine stall.
 
But like said, IT CAN idle like it should. But after it stalled and i start it again it doesnt directly idle good with out stalling again.
 
Only thing i noticed yesterday on the way back that the afr was dropping at a 0.6 bar vacuum at the moment it is going to stall but above and when its idling ok its nice around 12 / 13 were it seems to idle best.
 
 
 
So i just dropped this in here in case somebody has had this before, below some specs of the car.
 
rx7 FC TII(s5)
streetported engine, stock turbo with ported wastegate
TB mod
all emission removed
a/c also removed
walbro 255lph fuel pump, aeromotive fpr, 800cc secundair
apexi power fc from 93 FD with the banzai racing adapter kit
3" exhaust
simple intake with apexi filter
act prolite flywheel with extreme clutch kit (5 pad sprung)
ignition amplifier
 

[- Fezcat -]

have you pressure tested the IC system - Sounds like a boost leak to me

[m1tch]

Also check the blanking plates where the airpump has been removed, those can leak causing massive issues with idle - also, where has the BAC valve gone?

[Prof]

Could also be the resting positon of the throttle - if you\'re spring is sticky, it could be trying to close up the throttle too much hence stalling out.
 
Try moving the throttle lever on the throttle body manually - see if you can pull it shut and cause it to stall - if so, then the spring has some give in it and you need to adjust the minimum throttle position.  I have a similar problem - which I think is caused by this and a sticking throttle cable (seems to have 2 resting positions when warm).

[GeenIdee]

Thanks for the reactions so far,
 
Fazcat, that is something i haven\'t tried yet. Any suggestions for an easy way of doing that?
 
 
Mitch, i am pretty sure that\'s closed and somehow we don\'t think it is a vacuum leak becaus it does idle well at certain moments. We did tought about the one way valve in the vacuum hose for the power brake but when it does run good and u press the brake pedal multiple times in a row the engine does catch that up so it doesnt stall.
 
Uhm, bac vavle? Think that is somewhere... in the back yard or so.. hehe
 
Prof, what happens when i ajust that minimum position so its a bit more open and then adjust the rpm with the apexi?
 
 
I am not alone by the way, i am trying to figure this out with a local specialist. So if you read a "we", then i mean myself and him.

[Prof]

The adjuster on the throttle body is just an end stop for the throttle plates - it sets the minimum throttle position - as you still need the throttle \'slightly open\' to maintain an idle (I think), there is a hole in the throttle body for idle air pass, and also the BAC if you still have it will still pass some air.
 
I guess by modded throttle - you mean removal of the secondary throttle plates?

[- Fezcat -]

I\'ve never done it with an fc lol. It sounds like there\'s a pressure leak somewhere in the intake piping. i would  check all of the pipes, make sure they\'re all ft.


Pressure test would be blocking both ends of the IC system, and pumping air into it. Then listen for any escaping air

[GeenIdee]

@prof,
 
double throttle system removed and coolant flow cut off / removed.
 
But there is an adjustment screw there so u can adjust how far its closing. At first i set it like said int he workshop manual but closed it a bit more after the first start due high idle.
 
 
@fezcat,
 
yea i know what u mean. Done this with intercoolers but i guess i thought about the compleet intake lol.

[GeenIdee]

Just took the car out again to see what its doing.
 
Like said before, while driving and pressing the clutch, it will drop to idle speed and then it drops lower to stall.
 
Pulled over to see what it does and suddenly it ran good. But before i started driving again it wanted to drop in rpm from out of nowhere.
 
And while driving we went back to the staling again.

[Prof]

On the stock ECU - there is a switch on the clutch pedal that controls fuel cut on decelleration - not sure if the Power FC uses this switch, but you could try disconnecting it on the pedal to see if the problem is electrical or not.
 
Other than that I\'m out of ideas....

[GeenIdee]

Good point!
 
However, im not sure tough, i thought it didnt made any difference if i put in nutral.
 
But, maby you know this aswell, does it also work while standing still or is that only while driving? The fuel cut i mean.

[Prof]

Good point!
 
However, im not sure tough, i thought it didnt made any difference if i put in nutral.
 
But, maby you know this aswell, does it also work while standing still or is that only while driving? The fuel cut i mean.

I think it\'s only on deceleration (lift off) it either cuts fuel to one or both rotors depending on clutch switch - I presume it only cuts one if you operate the clutch as that indicates either changing gear (disengaging engine from transmission means the engine would otherwise die if no fuel at all was being injected), or coming to a stop.

[B.Martin]

OFF TOPIC

I love your engine bay Geenidee! How much you pay for that rad and fan set up? I think i want one, also best of luck with your problems. Sorry i\'m unable to offer something of use, BUT Prof is THE MAN!

[GeenIdee]

hey thanks,
 
did post a project topic (not sure if it is the right secion tough), but not much to see yet becaus i try to do things in the winter. And now its summer.
 
http://www.mazdarotaryclub.com/forums/showthread.php?t=71216
 
 
What i am planning to do at this moment is visualy check the intake and recheck for vacuum leaks. I am going to order ACV and another gasket (cant find the bac valve gasket ?) and then i am going to reinstall the block off plates to make absolutly sure that is ok. At this moment is mounted with stuff that is used to close transmission cases at VW.
 
If it is not better after that i am going to try out the clutch switch.

[GeenIdee]

I give up.
 
I\'m out of idea\'s.