backfire and breaking up issues

[oLemurs]

Hello everyone, my sr20det s13 has been having issues when it gets into boost it will backfire very bad. this only happens when the engine is very warm and it seems like it gets worse the warmer it gets. when the engine is cold i can get a good 3-4 WOT pulls before it starts to break up and when it does break up usually it backfires alot and stops accelerating pretty much completely. this issue only started happening after i swapped in my s15 turbo, here is what ive looked over. new copper plugs, tried .22 .25 .28 gap and no change. R8 coil packs upgrade. the only other new parts on this is my used HKS adjustable wastegate. any help is appreciated and before you start YES i did use search but its been months that my cars been down and i cant seem to figure out this shitty issue. also it throws no codes for anything.

also boosts to around 13 psi and holds it until it starts to break up

[Silv1401]

What heat rating are the plugs you're using? I had the same issue when I got my KA-T S14. WOT would cause a lot of bogging and black smoke, max psi was usually about 4psi, out of a tune meant for 16psi. Originally my wastegate flange was warped, and the gasket was blown (2-point flanges are dumb, btw) and I fixed it, which managed to get me a couple more PSI of boost. Then changed my plugs, and went up a heat rating from 6 to 7s. Instant fix. So, check your wastegate for proper plumbing, and seal around the exhaust side. Then try upping your plug heat range if that doesn't work.

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[jedi03]

agreed sounds like blowing out the spark...close the gap as opposed to opening it and check what your actual boost is, had buddy who was unknowingly overboosting his tune by ~15psi (evo) and kept wondering what was going on, got a good boost guage and turned down the boost then all was good!

[oLemurs]

Originally Posted by jedi03

agreed sounds like blowing out the spark...close the gap as opposed to opening it and check what your actual boost is, had buddy who was unknowingly overboosting his tune by ~15psi (evo) and kept wondering what was going on, got a good boost guage and turned down the boost then all was good!

i will just try turning down the boost most of the way, will check in later thanks for the help

[brndck]

+1 for check your boost level.
sounds like you need to check quite a number of things before we can help you pinpoint the issue

FAST

Fuel
Air
Spark
Timing

[jdmgtom]

I had similar issues with my s13 sr20det running worse when temps were up. My tuner told me it was due to my stock injectors. I upgraded to 550cc DW injectors and z32 MAF and running a s15 turbo as well and got a rom tune. The new injectors or the new MAF seemed to fix the issue but then again my car is still not 100%. I also bought a brand new HKS actuator and a Apexi 1.1mm headgasket with ARP head studs. So I haven't driven the car long enough with the new setup to see if it really fixed anything.

[brndck]

Originally Posted by jdmgtom

I had similar issues with my s13 sr20det running worse when temps were up. My tuner told me it was due to my stock injectors.

uhhhhhh that sounds like BS.

did you have a upgraded turbo or were you running more boost than the injectors could supply fuel for?

[jdmgtom]

Originally Posted by brndck

uhhhhhh that sounds like BS.

did you have a upgraded turbo or were you running more boost than the injectors could supply fuel for?

At the time, I was only running a s15 turbo and everything else was stock, with basic bolt on's running stock boost but even when I had the stock s13 t25 turbo, it was doing the same thing but a lot worse. That was the main reason I upgraded to a s15 turbo because I was convinced that the t25 was the cause. I will say that I f'd up and made a noob mistake with my s15 turbo, I turned the rod and probably messed up the diaphragm on the stock actuator thinking it was adjustable, that's the reason why I bought a new HKS actuator.

[brndck]

Originally Posted by jdmgtom

At the time, I was only running a s15 turbo and everything else was stock, with basic bolt on's running stock boost but even when I had the stock s13 t25 turbo, it was doing the same thing but a lot worse. That was the main reason I upgraded to a s15 turbo because I was convinced that the t25 was the cause. I will say that I f'd up and made a noob mistake with my s15 turbo, I turned the rod and probably messed up the diaphragm on the stock actuator thinking it was adjustable, that's the reason why I bought a new HKS actuator.

boost gauge. you need a boost gauge. if you don't even know what you're pushing, you can't start diagnosing shit. install the new hks actuator, set it to 7psi, then start troubleshooting.

[Shouldabeen11b]

Yeah I’m having the same issue with my car. S13 sr20 with a 3871r rom tune and z32 maf everything brand new out of box. Also a 255 warlboro. The first few pulls I can pull all the way to redline, but after that I will hit a brick wall of a twostep sounding breaking up, and I have to shutoff the car and turn it back on for it to stop. I’ve been fighting it for two months so if anyone has any ideas please help. I’m tuned at 12 lbs but only running seven Bc I have an internal wastegate and I’m scared to splice into the vaccum line on the turbo that came with it.

Edit: also running 750cc. Injectors and all the o rings are good

[oLemurs]

Originally Posted by Shouldabeen11b

Yeah I’m having the same issue with my car. S13 sr20 with a 3871r rom tune and z32 maf everything brand new out of box. Also a 255 warlboro. The first few pulls I can pull all the way to redline, but after that I will hit a brick wall of a twostep sounding breaking up, and I have to shutoff the car and turn it back on for it to stop. I’ve been fighting it for two months so if anyone has any ideas please help. I’m tuned at 12 lbs but only running seven Bc I have an internal wastegate and I’m scared to splice into the vaccum line on the turbo that came with it.

Edit: also running 750cc. Injectors and all the o rings are good

exactly whats happening to me im just on a pretty much stock motor

[oLemurs]

Alright got some data logs, here selected is the point of break up. the only thing i notice is the o2 sensor
C=RPM D- water temp E=battery F=throttle G=timing H-AAC I=injector J=o2 K=MAF L=MPG also shouldnt my o2 sensor be fluctuating? its a pretty new one im wondering if i should swap a fresh one in. i still get no codes

[Shouldabeen11b]

did you ever figure this out? im still lost.

[S14rebuild]

Tps is reading 3.88v and maf is at 4.54 idk if thats right...seems like the maf is almost maxed out... idk though. And yes the o2 should fluctuate

[Kingtal0n]

1. pressure test system to 20psi "boost leak test"
2. collect wideband data somehow, either use video or a data logger with the wideband
3. tune the engine properly