help, newbie tuner stalls when reved hard cuts out when wot or over 8psi

[dirtmann9]

hey everyone looking for some help or tips on my new car. i bought it already built but with some tuning needed. Here is a list of upgrades all with less than 500 miles. Engine was pulled and a rebuilt JDM was installed. 1mm over bore, ground and polished crank, block decked, new pistons, rings ect. Head was rebulit with new valves and springs and a high flow valve job done. head was also decked and a steel shim gasket installed. Fuel injectors upgraded along with the fuel pump and a adjustable fuel guage. A lexus AFM and a blitz air filter and blow off valve. The turbo was machined out to accept a T-60 cassette, coolez inter cooler piping. It also has a double stainless steel down pipe conected to a HKS super sport exhaust with test pipe

ok heres my issues. the car runs great and pulls hard if driven normal and boosted moderately. if you free rev it or push clutch in after hard take off it will stumble flash ses light and then stall. if you tromp the throttle it builds boost and cuts out or if the boost goes above the 8psi the fatory guage reeds it cuts out. finally when boosting in 4th and 5th the ses light comes on at times. idle is right around 1200rpms which i think is a bit high.

the car has a hks fcd but not sure if its working. i have tried all the settings in 3s and nothing has changed. 0-3-6-9-12. it is also wired up for an aem tru boost which is not working either at least the guage is not working.

thanks for any input you may have. I have already checked the intercooler piping for leaks and none found.

 

[Nghty89]

What size injectors? That lex afm will cause issues on stock injectors without tuning. And what do you mean by steel 'shim' gasket?

 

[89supra7mgte]

Sometimes an aftermarket bov on an afm will cause the stalling, has happened to me a few times but not as often as most people on here claim. the cause of the stall, is the release of the metered air, where in most cases it is recirculated to accordion tube. As far as when you are in boost, that could be a boost leak, have you performed the boost leak test? Do you have any codes?

If you have no hard codes set, then make sure everything is cleared out, do your free rev and get it to stall, and have ses light come on. Have the pins jumped (e1 and te1) if it stalls you should get your code. Be aware that with pins jumped you will get a code 51. My car was doing the same,but would not set a hard code, it was an intermittent afm, the only time i could get the code was by doing this. (and yes i know when the car dies with the key on the check engine light does come on regardless of codes or not)

 

[casgallo]

^need more info on your fuel setup. Do you know what fuel pump or "adjustable fuel guage" you have? (regulator?)

also what codes is it giving you that is a wonderful place to start.

perhaps you are hitting fuel cut? fcd not working? sounds like you need to slow down the boosting and figure out how everything is wired up? try using no boost contoller? just my opinions.

idle does seem high too, linkage returning to throttle closed position?

 

[gaboonviper85]

Lex afm has nothing to do with stalling....odds are it's you blow off valve....stock system runs a recirculated bypass valve which doesn't let metered air leave the system....a blow off blows metered air out which cause an extreamly rich condition at the moment of blow off which sometimes causes stalling....youl have to learn to drive and keep the engine turning...Aka when you blow off don't hold the clutch for too long as that will let the motor shut off

 

[casgallo]

bov does not explain cutting out at WOT at 8+psi?

 

[89supra7mgte]

Not unless the bov is not sealing up (being forced open by boost) letting air out, doing the same thing as when it purges, or vents? Would be a boost leak.

EDIT we still need more info on codes as well

 

[dirtmann9]

thanks for all the imput so far guys. I have done some tinkering and it seems to run better but still not right. I dont know exactly what i have done but it boost better. heres what i did do. i double checked all my hard pipes and re adjusted some of the connecting hoses and even double clamped any that were in question and I dont think im getting a boost leak. i took off the maf and checked the wiring and connections and cleaned it. the previous owner has a large bolt ran through the bottom opening that covers half of the opening. not sure if that should be like that but i left the bolt in? finally i tightened down the bov set spring to almost full in.

car still dies after reved hard or when clutch is pushed in after hard take off to a stop. I have learned to drive to avoid it most of the time. the boost is much smoother and doesnt cut out as easy until i reach full boost (8psi+ ?) it doesnt cut out half as bad as it did before my tinkering.

i am still not sure on the size fo the injectors but i know they are not stock as well as an upgraded fuel pump. its running about 53psi at idle if that helps.

How do i get the codes out, yes the ses light comes on and goes off when the stalling or rought idle after hard rev occurs. what type of code reader do i need and what is the process of getting the codes.

I plan on taking the non working aem tru boost as well as the hks fcd out of the car next. i will update more after that.
THANKS AGAIN EVERYONE.

 

[dirtmann9]

Not unless the bov is not sealing up (being forced open by boost) letting air out, doing the same thing as when it purges, or vents? Would be a boost leak.

EDIT we still need more info on codes as well

now that you mentioned it I think it may be related to the bov. i adjusted the spring in which would make it harder to open right? I still to hear a hiss noise not the bov blowing off but under hard boost like its leaking which is initially why i started checking my hard pipe connections. could that be the bov leaking out because of too much pressure?

 

[89supra7mgte]

the leak is either your bov or that is the wastegate opeing up under steady boost.

to read codes you need to jump the pins in the diag connector by battery, use paperclip and jump pins te1 and e1. Take note that with pins jumped if you press on throttle the check engine light will set a code 51 as well as having the ac on. You read them by counting flashes too btw.

 

[gaboonviper85]

bov does not explain cutting out at WOT at 8+psi?

Improper spark plug gapping does though....

 

[89supra7mgte]

^ or wrong plugs maybe as well

 

[dirtmann9]

I didnt have time over the weekend to do much to the engine since my new suspension arrived :biglaugh: I spent about 8 hours removing and installing all new tokico illumina TEMS struts and new Tananbe springs. Really happy with the new ride and boy were those old 150k struts worn out. i was hoping the chatter i was getting was all struts knocking but im thinking now it maybe the center support shaft bearing having a little play and comboed with stage 3 clutch it chatters a bit and clunks on certain take offs. worse when backing up. any one else have any similar issues. I am thinking of a aluminum 1 piece drive shaft to do away with the 2 piece. any thoughts pros or cons.

 

[dirtmann9]

Improper spark plug gapping does though....

Ok i will try an pull the plugs. i was planning on doing so soon any ways. do you prefer running the factory denso plugs or is there another plug i should consider since it the fuel and engine are modified? Thanks

 

[89supra7mgte]

If you do the one piece have it priced out at a driveline shop, i got mine for 98 bucks, it is built with the strength of the ones they use in there rock crawlers. (will handle up to 600/600, when and if i take this car that far)

 

[supraguy@aol]

As far as the dying at throttle-off, I would say it's your BOV. The car isn't set up to vent the bov to atmosphere. Hopefully I didn't misread anything you wrote, but using stock air metering(even the lex MAF) means that the air is metered, and then appropriate fuel is added. When you let off the gas, the bov opens and lets some of that air out, but the ECU has already determined the amount of fuel to inject. Since alot of that air is now not present to mix with that fuel, you go into a very rich condition temporarily, causing stumbling and stalling. I'm not sure if someone else mentioned this already.

 

[dirtmann9]

As far as the dying at throttle-off, I would say it's your BOV. The car isn't set up to vent the bov to atmosphere. Hopefully I didn't misread anything you wrote, but using stock air metering(even the lex MAF) means that the air is metered, and then appropriate fuel is added. When you let off the gas, the bov opens and lets some of that air out, but the ECU has already determined the amount of fuel to inject. Since alot of that air is now not present to mix with that fuel, you go into a very rich condition temporarily, causing stumbling and stalling. I'm not sure if someone else mentioned this already.

Hello, thanks for the input. yes i am thinking that you are correct as well as a few other post which reference similar. is there any way to correct it ?

 

[supraguy@aol]

Hello, thanks for the input. yes i am thinking that you are correct as well as a few other post which reference similar. is there any way to correct it ?

MAFT baby- Yeah!!!

LOL!- A MAFT or MAFT pro will eliminate the need for the LEX MAF, and allow an atmospherically-vented BOV. The easiest and cheapest cure is to have a recirculated BOV, like the original bypass valve was done. However, I don't think your model of BOV can be recirculated. Another relatively cheap method is an SAFC or similar, that accomodates a throttle-off compensation, so that you don't get the over-rich condition.

However, a MAFT pro is a great upgrade path, if you're looking to eventually build your HP to higher(but not crazy huge) levels. It allows you to program your injector size, plug n' play an electronic boost controller, remove the restrictions of air metering, tune fuel curves, and in some cases, even control the timing curve. I've got the basic MAFT, and it's been 100% trouble free now for 4 years. And the MAFT pro is miles ahead of the MAFT.

 

[MKIIISupraGuy]

I just read all of this. To Recap if you are venting the BOV to atmosphere the car will in fact stall if you either rev and lift the gas pedal, or accelerate hard and shift. I might have missed it, and doing the MAFT setup was mentioned already, but that is expensive. If your on a budget, why don't you search the forum for what is called the "dash-pot mod". It's what I would do.

OK , I was nice and did it for you. Let us know if this helps, it should. :icon_bigg

Dashpot mod thread

 

[89supra7mgte]

venting the bov to atmo doesnt always cause the car to stall, mine never dies, or hasnt yet. revving it up and lettin off doesnt do anything either. I had a bad afm that would cause the same conditions.