Subaru Help

[kk6rgn]

I recently had my subaru 2.5 turbo dohc rebuilt and added a bigger turbo & intercooler with fans and a standalone fuel pressure regulator and had it retuned . The issue, Is the car runs Perfect for 20 to 25 minutes then it starts bucking / stumbling like it is running out of fuel or over fueling. Now I have changed all 4 coils & every sensor on this motor, I have checked all my grounds, I have even wired the New fuel pump direct bypassing everything from a seperate battery. It's like clock work the car runs like a bat out of hell for 20 to 25 minutes then she starts bucking. I will let the motor cool and she runs great for 20 more minutes. I am at my witts end and don't know what to try next, Thinking about installing my gopro pointed at my fuel gauge to see what's happening when it starts acting up. I am willing to pay someone to troubleshoot my issue because I have run out of ideas .

Thanks for reading
Johnny

 

[JDDurfey]

So you are not sure that it isn't starving for fuel? I had a pick up that did that and found out after looking at a whole bunch of things that there was a rag in the fuel tank. After running for a while it would get sucked over the fuel pick up and starve the engine.

I would get the fuel pressure gauge where you can read it while driving so you can rule that out.

 

[kk6rgn]

Thanks JD , I am at lost, new motor,new intercooler,new sensors ,new coils ,new turbo,new fuel pump,and 4 weeks of trouble shooting . I need to find someone that i can pay to troubleshoot this for me because i have just about given up.

 

[brad inch]

clean out the gas tank, but the biggest thing is make sure it has a vent and make sure its big enough.poeple sometime just use a vented cap,thats not the best way,next time it acts up stop and open the cap.then close it and try to drive it.
good luck brad

 

[JDDurfey]

clean out the gas tank, but the biggest thing is make sure it has a vent and make sure its big enough.poeple sometime just use a vented cap,thats not the best way,next time it acts up stop and open the cap.then close it and try to drive it.
good luck brad

I forgot about fuel tank venting. That could very well be the problem too.

 

[kk6rgn]

Thanks guys , Keep up the ideas, I ruled the gas tank out , I pulled the tank and rinsed it out & also unscrewed the cap thinking it was getting air locked.But thanks guys, I am down to trying anything at this point, Currently i brought the car to the guy who built the motor to have a look at it and make sure one of the valves is not getting stuck .
Johnny

 

[kk6rgn]

Thought i would share That i found the gremlin in my motor , I tried a suggestion that someone posted on another site and sure enough it worked. I shimmed out the camshaft sensor about 1/8 of a inch with a flat washer between the case and the sensor. That did the trick, I put about 42 miles on it yesterday without one hiccup.I am not sure why this is but I am assuming that because I am running a newer style STI case that probably the new case requires a different (shorter) sensor . I spent 4 weeks troubleshooting this issue and I hope this will help someone in the future .
Johnny

 

[jon coleman]

heat expands metal, thnx for the tipi Do like the 'fix', the proverbial ' 10 cent washer'

 

[brad inch]

thanks for the update

 

[dzrt performance]

Thought i would share That i found the gremlin in my motor , I tried a suggestion that someone posted on another site and sure enough it worked. I shimmed out the camshaft sensor about 1/8 of a inch with a flat washer between the case and the sensor. That did the trick, I put about 42 miles on it yesterday without one hiccup.I am not sure why this is but I am assuming that because I am running a newer style STI case that probably the new case requires a different (shorter) sensor . I spent 4 weeks troubleshooting this issue and I hope this will help someone in the future .
Johnny

my guess would be the shimming improved the gap on the cam sensor. loose the cam sensor, its done. a good logging ecu would have made this easy to spot,.