First turbo start stall when no throttle
 

Hi everybody,
That is my first post and i wanted to thanks you because this site helped me MANY times. i have a 91 stock ecu when i puted the turbo it starts stalling as soon i totally release throttle. Until I keep put a little of throttle no problem. My iddle was perfect before the turbo was installed (a little low because of emissions tests).
​​​​​​ I saw a lot of thread with approximately the same problem specially one with the exact same problem (it turns out to be the maf too close from the turbo but i have two 90 degree hose and adapter in between i'm not concerned). Many people thinks that it should be a vacuum leak my own routing from the turbo seems really fine (i supposed that the rest of the vacuum line would have leaked before the turbo, and then i would not have this perfect idle before? Am i right or the pressure could crack old lines and provoc a leak?).

After readings i redirected the bov just before the turbo and i tried many setup for bov strenght.I also installed a tdr fuel unit without any change.
My iddle control unit is now vta, with check valve + filter I also checked the afr which suddently goes 20+ when stalling (i supposed it is normal if it s stall,no?).
If i keep a little of gaz the afr will keep perfects values, as soon as i release totally the gaz, the value will rise suddently and then the engine will stall.
​​​​​
Without the turbo the car was NOT stalling even without o2 sensor at all. Now with the turbo i first tried with stock o2 sensor and now i have the o2 signal from my afr unit...no changes...

thanks!

Wtf did I just read.

maybe it s too long but i just want to be precise...sorry then

Engrish not primary language, so we'll let it slide.

Lol256,
you need a proper tunable ecu

Hi, yes no english at school for me... i'll try to correct it best i can asap. I'm sure your right for proper ecu but i need stock ecu by laws in my country and can't change it. I can richen (or opposite) at low revs only with my tdr but i think it will change nothing. I can't think that all flying miata, tdr kit and all working with stock ecu can t iddle or release the gas without stalling..? Are you sure anything else couldnt be my problem?

if you have to use stock ecu (TERRIBLE IDEA) then you can't vent the idle valve to atmosphere

Hi, ok that s very nice you tell me that! Can i ask you how i'll have to use the idle valve with stock ecu?? Injecting boost in there? Close it?? Another option i can t think to?

i would love to know why it didn t work with stock ecu but that s curiosity if you have time to spend! (Yes, i have a check valve how could it be a leak in the system? Is the ecu checking these value and don't like to see them different than main air intake?)

Thanks a lot

You'll have to use the idle valve in stock configuration as long as you have a stock ecu.

The air flow meter is measuring how much air is going into the engine. If the idle valve is pulling air from the atmosphere then the AFM isn't measuring that air.

Plumb the idle valve so that it pulls air from the intake after the AFM.

ok you are perfectly right some more air is comming. Ok so i read before that s iddle valve dont like pressure (why i went vat) do you think i'll not blow anything in there? Any option? Can i think to bypass this iddle vavle system(is it impossible to have a decent idle without it?)?
If i want to do this reroute to suck air after the maf like you guys said, i want the least possible "holes" on my silicon hoses system so do you think i can put this vacuum line with a air "T" directly on top of the point the bov is redirected (afer maf, before turbo). I mean one hole in the hose and both two line comming there, one sporadicaly blowing(bov) and one sucking air (at iddle so seems not at the same time).

thanks for your help.

is your BOV vent to atmosphere? with stock ecu it needs to recirculate back into the intake, after the MAF and before the turbo.

How do they know you have a stock ECU in your country? Do they do emissions testing? Visual inspection under the dash?

You can have a standalone ECU (like a megasquirt) set up like a piggyback, where the stock ECU is still there and functional, the OBD port will work, etc. but the engine is completely controlled by the standalone.

Hi, no i recirculated it before turbo and after maf like you said... the question was, if i can directly connect the iddle valve with a line directly to the hose that recirculate the bov (so only that point, before the turbo and after maf, to reinject both bov and to suck for iddle valve)???

Allholely...SadoFetish experts fist f**** your car to orgasm! Switzerland d = strict. I really understand your thinkings about stock ECU but that a conscient choice i made.

Ok guys thx a lot i did it and it works like a charm!!! You crazy fast &smart! Thx

Ausgezeichnet!