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Lean Condition. 03 wrx


thorne

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Ok, I've been kinda frustrated on this one and am sure it's a mechanical issue at this point. I've only had a issue like this once before and it was way leaner then this though and it was a fuel filter.

 

I'm running a similar map to the one I street and dyno tuned on my car which was dead on before @ 11.5 I mean on the nose. For the past month I've seen it drift to 12. Which is to lean . The IDC's are the same. The learning seems the same at first and then drifts by ~5% max.

 

The map like i said as almost identical to the one i dyno tuned that came out @ 11.5 dead on.

 

What pieces can cause this?

 

Clogged injector ?

Fuel Pump failure ? How do I even test this?

vacum leak ?

Bad plugs?

 

 

I've just been banging my head over this. I hate mechanical issues. I can look at logs/maps and find issues quickly but this is just irking me to hell.

 

this is my car.

 

The car has 91k on it. Had it's plugs changed around 80 along with the timing belt.

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O2s? I'm not very familiar with your car, but I would start checking fuel pressure at the rail, if good you know everything is good up until the injectors. Scanning the O2s for slow or sluggish movement would indicate that they are getting worn out. Just some thoughts.
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My first thought would be a fuel pump or even dirty injectors, and even more unlikely, Fuel Pressure Regulator? I don't know common failing points of Subarus but I would look into those before anything else. Depending how easy it is to get to your injectors I would inspect those first, simple to clean and could be an easy fix. Fuel pump, I don't know of any specific way to test that it's flowing properly or showing signs of failure, but do you have a fuel pressure gauge you can use? Process of elimination I suppose..

 

Another thing that occured to me, what type of fuel do you run through the car? I'm curious to know when gas stations start doing their winter fuel mixes(If there is such a thing?).. you could be seeing that difference?

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My first thought would be a fuel pump or even dirty injectors, and even more unlikely, Fuel Pressure Regulator? I don't know common failing points of Subarus but I would look into those before anything else. Depending how easy it is to get to your injectors I would inspect those first, simple to clean and could be an easy fix. Fuel pump, I don't know of any specific way to test that it's flowing properly or showing signs of failure, but do you have a fuel pressure gauge you can use? Process of elimination I suppose..

 

Another thing that occured to me, what type of fuel do you run through the car? I'm curious to know when gas stations start doing their winter fuel mixes.. you could be seeing that difference?

Check while the car is under load, would be easy on dyno but that is why fuel pressure testers are available electronically and/or long. (sorry Thorne I don't have a nice one like I was talking about.)

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I'm going over to IPS to use some of there resources saturday. My injectors are a BITCH. The issue has been happening since shortly after the last track day I was at. It was not winter blend then .

 

Gas wise I've done bp 93 and sunnoco 94. The thing thats bugging me is when I've richened it up it's seemed like it was not responding. I might strap it to the rollers this weekend.

 

As for the MAF. That is a option but the G/s it's reading is almost exactly the same as it was on earlier logs with in a few grams. The boost is holding fine. I'm going to back it off because of me worring but on the tests it held 22lbs with out a issue.

 

I just spoke to mike I'm going to test the fuel rail / clean the maf / and run a boost leak test.

 

Man the more I think about it the maf does sound like a very possible culporite.

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I'm going over to IPS to use some of there resources saturday. My injectors are a BITCH. The issue has been happening since shortly after the last track day I was at. It was not winter blend then .

 

Gas wise I've done bp 93 and sunnoco 94. The thing thats bugging me is when I've richened it up it's seemed like it was not responding. I might strap it to the rollers this weekend.

 

As for the MAF. That is a option but the G/s it's reading is almost exactly the same as it was on earlier logs with in a few grams. The boost is holding fine. I'm going to back it off because of me worring but on the tests it held 22lbs with out a issue.

 

I just spoke to mike I'm going to test the fuel rail / clean the maf / and run a boost leak test.

 

Man the more I think about it the maf does sound like a very possible culporite.

 

My MAF caused my car to load up on fuel in half throttle conditions and run lean up top.. Unfortunately the MAF cleaner didn't help my problem either. Will your car run without the MAF? I simply had to un-plug mine(of course I had a CEL) and let the ECU run off it's learned tune and that pointed my problem directly to the MAF. If you can get away with that, give it a shot. If you have someone local, try swapping with a known good unit.

 

EDIT* I've heard of people having problems with air filters being really dirty and running into problems like this. Have you cleaned or recharged yours lately? before I found a faulty MAF, I found mine was filthy when I was troubleshooting my own problems .

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Just let it go boom. Then put in the new engine you really want.... :D

 

If had the money I would yank this motor right now and have me eather a 2.3 stroker or a 2.5 or maybe 2.7 muahahha.

 

 

nd2 I'll be upthere pm me your number I'll let you know what time. This has shown me that the safe modes in the roms really do work.

 

 

So saturday.

 

Pressure test #1

Fuel pressure test #2

Clean maf for good messure #3

I might pull a plug on Cyl #3 or #2 since I did show a misfire code. The problem with the misfire codes is I have a lightened flywheel so people report tossing false ones all the time.

 

Thanks for the input guys. Again Praise Fuji Heavy Industries for making a very adaptive ecu.

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clean your mass air flow sensor, those cars uses the same maf as toyota's when you take it out look at it there is a intake temp bulb and then when you look those it there are 2 wires, those read the amount of air flow,, i bet they are dirty, go to like napa and get crc maf cleaner spray it on the bulb and then down on those 2 wires, and blow gun it clean.
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