Need Advice; Sputters.

[s13passion]

Okay this has been an ongoing problem and after trying a few things and checking others it's still happening.

I have an SR20DET with basic mods. I've replaced the coolant temp sensor, 02 sensor, plugs, adjusted timing, fuel pump ( walbro 255 ) checked injectors they're still good, cleaned my MAF, IACV. Probably more but can't think of it.

The car runs fine seems to have no problems at first. After about 15-20 minutes of semi-hard driving ( i do this so i can duplicate the problem when i'm trying to troubleshoot ) the car begins to stutter at the 3-4k RPM range. Its only slight at first, but gradually after a few minutes it gets worse and worse. Until from a stop, I have to shift around 2k rpm or give it more throttle in which it responds with stuttering and eventually some backfire. The car will shake and and bog/stutter. I'm guessing its flooding out somehow, as it smells like unburnt and just generally has the symptoms.

Would love some more ideas about this, as it only happens after driving a little and warming up, makes it harder to find.

Thanks fellas lemme know if you come up with anything.

[s13passion]

Bump.

[jdm_master_X]

how old is your fuel filter?

[s13passion]

Fuel filter is pretty old, I bought a Z32 one last year some time, I don't typically put many miles on my car because work isn't very far, but I'd say mileagewise; maybe 6-7k, and about 1 year 6 mo old.

[sviellvoicae]

same issue here man sputters after 5k rpm in every gear..... although it doesnt matter how long i drive for or how hot my engine is it will still do it, but it sounds like we might have the same problem.....please help guys...

[s13passion]

I was talking to Rotorimp this weekend about it, he gave me some ideas but I don't think it could be them.He suggested that I get a new battery ( optima redtop ) with new terminals, try to plug in a known-good MAF and try that, check injectors for correct resistance, replace the fuel filter.I've also seemingly got an air leak somewhere so I'm going to try and hook up one of those homemade leak test devices and maybe start narrowing this down.I'll keep you posted but you keep trying too maybe we can knock this out ><

[sviellvoicae]

i will... im about to do those exact thing as well

[s13passion]

Update:

So I replaced my spark plugs with some copper NGKs gapped at 1.1mm. Also cleaned out my coil packs with some alcohol and compressed air. Replaced the fuel filter with Z32 TT, cleaned the IACV with throttle body cleaner. I bought an optima redtop but haven't put it in yet, as my battery is old and was victim to spillage. I test drove it after the fuel filter and plugs/coil cleaning, problem still persisted.After that I did the iacv and pulled a 12 from the ECU code. Says my MAF is bad. I'm going to go get an extra MAF, always good to have one around

I'll let you know if this works. Oh, another thing.After the test drive, my RPM's were going from 1600 idle to 1800 idle then back down, and back up to 1800, back and forth. Which DOES sound like a MAF issue.

But the high idle still exists, maybe switching out the MAF with a known good and after the cleaning it will help.

I'll keep you guys posted! If you've tried anything else let me know.Was going to check my TPS voltage when I get to work ( Avionics USAF ).