Car is breaking up around 4k rpm

[midnightracingsr]

ok guys im going to try to be as specific as possible any help is greatly appreciated I want to solve this but im out of ideas.

here is the problem:s13 redtop sr20det. at 7psi with stock smic and piping. it can hold boost fine and the vac at idle is around 21

The car basically falls on its face and breaks up around 4k rpm at wot when in boost. It doesnt do it in vac. I did the swap around 2-3 months ago. The symptoms only occured when the stock boost was increased to 9psi.

The list of things that I have tried:

Compression test. all cylinders are at about 140

new Coolant temp sensor

hooked up the modis diagnostic scanner and checked the ecu for codes. code 55 system ok. was the only one. I checked the mas voltage.. good. the tps.was good. the o2 was good so i didnt change that. drove the car with the modis and the maf, o2, coolant temp, tps and everything was in working order.

Looked for boost leaks only found a bad bypass valve so i changed that. but i am ordering a full greedy kit because i think that is my problem.

changed the plugs several times with several diff gaps.

looked at the coil packs the spark to me seems weak because they are not bright white. they are kind of orange.

I changed the fuel filter to a z32 tt filter and I am runing a walbro.

Changed the bypass valve to one from an 04 evo.

Things I think it could be.....

Right now I dont know. but someone told me maybe the fuel pressure is too high

also that there is a leak in the piping or vac hoses.

I have tried anything and i really want my car to be running good again. thanks for all the help.

[kainvamp]

I was having the same type of problems, ran fine till about 4k rpm then took a crap. I know my problem is that it is running way to rich, and on top of it i had a beat bypass valve. After I changed that, it runs alot better, but still rich, doesnt bog anymore for me now, but you could have way too much fuel too.

[Silvia007]

Clean your MAFS sensor with some electrical contact cleaner. Comes in a spray at local auto parts stores.

[supreamS14]

My sr breaks up around 3-4 rpm range in or out of boost. It runs 100% other than that. seems like its too rich cuz it will leave a transparrent cloud of gas behind me at 3-4k rpm. I cleaned the maf. with CRC maf cleaner already!

[natguerrero]

i was having the same problem too ..but i checked all the turbo piping and there was a leak in one of the couplers , it was pretty small but when i hit boost it would leak out , not creating boost .so check all the piping ...

[MMotorsports]

I agree with natguerrero. It sounds like you have a boost leak somewere. Now when you say it falls on its face does it start bucking real hard if so I would defently agree that you have a boost leak.

[Project240]

Do you ever get a rough idle? I'm thinking that one of your coil packs could be going bad, or could possibly just be loose? From time to time, I'd get a rough idle, my car would sound like a Subaru, and it would break up during driving. Turns out one of my coil packs was missing the bolt that holds it down, so it was coming loose

Try pulling them out one a time while the car's running to check them. Might not help, but at least it's an easy test

[Emperor_Tha]

check afr.... My car would would bog really bad at full boost around 4k. My car would run extremely lean which was cause by a bad walbaro fuel pump

[MagnumP_I]

you guys might wanna check where your smic is to see if stock Blow off valve is still there some of you might have 2 blow off valves. My friend had the same problem so you might be having a leak.

[rhdsilvia]

could be a ground on the engine. if its not grounded right it will do that.

[Tx-Sx-FS]

similar kat problem..my guess is tune so far...1st gear is great, 2nd and passed no more than 45% throttle or bogs starting 3.8k - 6k it just sputters through rpms with no power, so i let off the throttle ...seems like in low throttle is runs good just not high (afc) so what should the numbers be at 12psi on T25? 370cc injectors.

[redtop91]

Do you ever get a rough idle? I'm thinking that one of your coil packs could be going bad, or could possibly just be loose? From time to time, I'd get a rough idle, my car would sound like a Subaru, and it would break up during driving. Turns out one of my coil packs was missing the bolt that holds it down, so it was coming loose

Try pulling them out one a time while the car's running to check them. Might not help, but at least it's an easy test

1000000% in agreement, at least in the general area of the problem. My SR would break up right around 4k for awhile and then one day one of the coilpacks stopped firing. Coilpacks generally don't go bad, which is where I kind of disagree. Turns out my coilpack wiring harness was corroding and shorting when I rev'd up. Problems related to a specific RPM are almost always electrical in my experience. I'd bet money that your car starts sounding/running like a Subie soon.

you guys might wanna check where your smic is to see if stock Blow off valve is still there some of you might have 2 blow off valves. My friend had the same problem so you might be having a leak.

.......

[DRIFTINIZ]

what kind of boost controller do you have? I know I had an manual controller on mine and I kept spiking when I'd hit like 4-5K.....maybe watch your boost gauge next time it breaks up on you?