Rough idle/stalling issue

[Doat]

Story is when I start my car up it idles high when it's cold like normal then after like 5-10min it starts to drop and when it gets warmed up a bit the idle sometimes bounces like 200 rpm or so it sounds like I have big cams or something. Then when I back out or moving up a little bit like parking and such where you drive then engage the clutch to shift into neutral the idle will stumble and sometimes stall out usually if I turn the A/C on it will prevent it from stalling but not all of the time. I cleared the codes and checked for some but I get nothing, I have a Lexus AFM with new sensors, Precision 550CC injectors, and 3in divorced downpipe. Now I think this problem is caused by my blow off valve because when I hit boost I feel it pull until it gets to max stock boost levels at about 3,000 RPM then it feels like it's out of puffs also when I left off of the throttle I hear a sort of strange sound I can't really describe it sort of sounds like taking a swig of water and whistle with it in your mouth. It's a bad description but I can't think of how to describe it right now lol. Yesterday when I was removing my Blitz boost controller because apparently the solenoid for it doesn't work because I couldn't control the boost I removed the factory blow off valve and blew through it and felt it come out of the other side. I think that is the reason why my boost controller wasn't actually working and probably the cause of my idle/stalling problem but I wanted to get some other info on what to check for and how to do it. I thought about spraying brake cleaner on vac lines and turbo hoses to see if they are leaking or not sealed properly and wanted to know if there is a better way of checking for leaks or what areas to inspect. Oh and in the morning I am taking an old Tial bov that a friend of mine gave me to my shop guy to see if he can fab something to replace my charge pipe and see if it works and solves my problems.

I have done a lot of research on this issue but as usual my problem is not the same as 99% of the stuff I come across lol.

 

[Doat]

Well I replaced my BOV with a Turbosmart plumb back and it fixed the idling issue and almost fixed my stalling problem I test drove it and it didn't stall out or almost stall out then when I got home I went up my driveway and when I was getting to my spot I shifted into neutral and it stalled out as I pulled into my spot. Any ideas?

 

[BryanDyer]

Have you checked the da shoot or the little diaphragm under the throttle body? Even my car stalls our everyone once in a while but it's only when throwing it in nuetral while going up a steep hill and causes the rpms to drop fast.

 

[Doat]

You mean the sponge like filter thing that just hangs under the throttle body? How do I check that exactly? It doesn't look like it's blocked or anything.

 

[BryanDyer]

It's somewhere in the tsrm, it tells you how to check if it is functioning properly.

 

[Doat]

I'll check it out after work thanks

 

[7M4EVR]

I'm leaning toward a vac leak here BC it may be getting enough when you are in load but when u go into nuetral it stumbles...other than that it could be so many things and u really have to put in the work and check them off the list...maf sensor, plug wires, injectors, isc valve gummed up...

you said new sensor and injectors so I would maybe put your old maf sensor back on and see what that does, then take a screw driver to your ear and to each of your injectors with the car running and see if you can hear them clicking...then check your plug wires, then on to pressurizing and checking for boost leaks

 

[Suprapowaz!(2)]

Does your BOV vent to atmosphere, or route back into the intake pipe like the stock one does?

 

[Doat]

My BOV recirculates into the intake pipe.

If my injectors were not operating properly then wouldn't it feel like a misfire or something all of the time instead of just that specific moment when I quickly get on and off of the gas and clutch? I've heard having a lightweight flywheel can cause that happen and my Fidanza flywheel weighs 11.5lbs.

 

[Doat]

Well after the BOV install I put my boost controller back in and had it at 60% and it was only at about 8psi but the turbo was loud sounded like it was producing more boost than that and at about 3,000 rpm it felt like it lost that grunt. I will put the stock hose back on and do another test run and see if it's the controller not working properly.