s13 SR20DET stalls after boost

[TimsZee]

Recently got head over heels involved in a s13 coupe with a blacktop SR.. After buying it I found out that it need more work than thought. Anyways, got the car running and boosting correctly for the most part.

The car idles fine for the most part but after driving and going into boost and coasting after the car will stall if I'm not on the throttle. The wiring is good, vacuum lines are in their correct spots. The only thing that I can think of would be related to some fuel issues.. If anyone has any ideas or questions feel free to ask.

93 coupe
s13 black top
FMIC
t25 (running off wastegate)
walrbo 255
stock injectors
wiring specialties PRO harness
62/63 ecu
greddys BOV
SR maf

[240ss]

you need to recirculate your bov

[TimsZee]

you need to recirculate your bov

Thanks, I'm going to have to get a new intake pipe with some way to route the bov into it. I'll report back after I recirculate it.

[Flyin_bryan]

you don't have to recirculate it, Whats happening is that its not closing fast enough for the the idle circuit. Put a stiffer spring in the BOV. Just an idea that i found to work .

[Mikester]

I am going to assume it has a full 3" exhaust? If so, the lack of back pressure on the way down from high rpm(boosting) will cause the flywheel to spin 'too slow' in that moment where it dips below idle speed, then catches up with itself. Putting a 2.5in exhaust on a stock SR will yield less back pressure without impeding performance/flow. If anything, it will help performance all the way around.

As stated above, recirculating helps too. Since you already have a GReddy BOV, I wouldn't recommnend tightening it too much. The T25 isn't designed for a bunch of pressure with nowhere to go forcing itself backwards thru the compressor. That's a great way to prematurely pop the turbine.

Another thing you can do is change your spark plugs; and properly gap them. As plugs age, they don't put out as much spark... which will enhance the stalls coming off of boost.

Unfortunately, this problem you are describing is sort of 'normal'... silly as that may sound...

Recommend check/change plugs & put a smaller-diameter exhaust on it... In that order. DO NOT tighten the BOV spring if the BOV isn't leaking. The more stray pressure it's able to let off, the better it is for your turbine.

[Flyin_bryan]

I guess what i'm saying is that i had this problem and that the BOV wasn't closing fast enough after boost and the car would stall. I replaced the spring so it would close faster and has never done it since, Whether your situation is as mine i'm not sure but that's what was causing the problem.

[ultimateirving]

try taking off the iacv and cleaning it. THis is what controls idle and helps catch the rpms upon Decel

[TimsZee]

you need to recirculate your bov

This sounds like the best way to solve this.. It just drops after i let off the throttle, just like it would do if there was no air to compensate for the fuel.. If that's all it is for now then thats quite fine.

[skyline_guy777]

My S14 SR does the same I blip the throttle and good to go seems to be a normal occurrence for these engines when running blow off valves that are atmospheric

[240ss]

This sounds like the best way to solve this.. It just drops after i let off the throttle, just like it would do if there was no air to compensate for the fuel.. If that's all it is for now then thats quite fine.

Yeah my buddys sr was doing the exact same thing. Recirculated it and problem instantly solved.

Sent from my XT907 using Tapatalk

[mr.nismo.]

I have a blitz atmospheric BOV and thought the non recirc was causing my almost-stalls. Turns out my AAC wasn't adjusted properly. If say try that first. Takes very little work and you could at least rule it out

[ultimateirving]

I have a blitz atmospheric BOV and thought the non recirc was causing my almost-stalls. Turns out my AAC wasn't adjusted properly. If say try that first. Takes very little work and you could at least rule it out
^^^ this is what i was saying!!
Ive ran atmospheric for a few years now and never have a problem when letting off after boost. doesnt die or stumble unless my IACV was sticking

[Livinstrong]

I am going to assume it has a full 3" exhaust? If so, the lack of back pressure on the way down from high rpm(boosting) will cause the flywheel to spin 'too slow' in that moment where it dips below idle speed, then catches up with itself. Putting a 2.5in exhaust on a stock SR will yield less back pressure without impeding performance/flow. If anything, it will help performance all the way around.

As stated above, recirculating helps too. Since you already have a GReddy BOV, I wouldn't recommnend tightening it too much. The T25 isn't designed for a bunch of pressure with nowhere to go forcing itself backwards thru the compressor. That's a great way to prematurely pop the turbine.

Another thing you can do is change your spark plugs; and properly gap them. As plugs age, they don't put out as much spark... which will enhance the stalls coming off of boost.

Unfortunately, this problem you are describing is sort of 'normal'... silly as that may sound...

Recommend check/change plugs & put a smaller-diameter exhaust on it... In that order. DO NOT tighten the BOV spring if the BOV isn't leaking. The more stray pressure it's able to let off, the better it is for your turbine.
I would disagree with your statement about back preasure. I have a nearly stock SR with 3" elbow, downpipe, test pipe to 3" mid steel all the way back and I have no issues with back pressure. Another thing to check- make sure you base timing is set properly. Mine was accidentally set retarded, and I had stalling/poor idle issues because of it. Good luck!

[TimsZee]

I would disagree with your statement about back preasure. I have a nearly stock SR with 3" elbow, downpipe, test pipe to 3" mid steel all the way back and I have no issues with back pressure. Another thing to check- make sure you base timing is set properly. Mine was accidentally set retarded, and I had stalling/poor idle issues because of it. Good luck!

It was timing.. Took the valve cover over a few weeks ago, spun the crank, check the notched in the CAS and fixed it. Runs MUCH better now, last guy who had the car didn't care what happened to it or what work went into it..