Engine Cut off when granny Shifting

Engine Cut off when granny Shifting

I have a problem with my 04 STI. This is the first major issue I have had with my STI. Just a back brief the 04 STI has 150,000 miles, changed TB and water pump, SP belt at 135,000, NEW aluminum radiator at 145,000 (this is when the problem started after replacing the OEM), Cold AIR at 110,000, STI came with the Turbo timer.

With that said I maintain my STI as per the manual with oil changes at every 2500 mile, Mobil ONE oil and filter only, and engine flushes every 4[SUP]th[/SUP] oil changes, with new spark plugs. And a visual inspection to see if any part could fail. Also I was getting somewhere in the ball park of 285 miles per tank now I can barely hit 235 miles to a tank (First sign that something is wrong).

I am getting ready to start going to stage one (my STI is still stock other than the parts listed above), until I felt a loss of power with my engine at 2 ? 4 RPMs running at 60 mph to 80 mph.

The engine also shuts off after going above the speed of 35 mph when the clutch is fully depressed and the RPMs drop below 1.5 RPMs (as of today I call this a ?dangerously unconvinced? really bad when downshifting to make a turn when the engine shuts off) . If the car is still going at 35 ? 80 mph, after lifting the clutch back up while in gear the engine will start as if nothing was wrong. If I am below the speed of 20 mph the clutch can be fully depressed and the engine will STAY ON (WTF). As soon as I go above the speed of 35 and up if the clutch is fully depressed then the engine SHUTS OFF (again WTF). While driving I feel a loss of power (like my STI is being held back) when I am just cursing at 65 mph the car will jerk back and forward jerk, the ride is really rough. If I try to open up between 2-3 RPMs in first gear and second gear it is jerky and not a smooth burn or smooth acceleration. Nothing like when I first got the car at 90,000. As of right now the car has no AC belt on. It is winter and I don't think I need it on.

Worst part of all, the engine is throwing NO! Codes! No check engine. I don't want to go to the dealer right away I wanted to ask you guys if there are any fix I could do before I buckled down and take it to Subaru.
Thanks again. :tard:

My first suggestion would be to take a log and replicate weird behavior.

Definitely try and log this.

It's literally turning off and on?

Ignition and electrical system would be where I'd start but this could be a real doozy to figure out.

Holy crap.... Subbed for important info!

First thing I would do is check all your vacuum lines and and connections. Have a boost leak test performed and a compression test. We can have a look at a log if you have a way to do that. This also could be fuel related in that the fuel pump may not be functioning properly above a specific load or RPM or the fuel pressure regulator may be bad.

I would really like to see a log though.

When i get a chance i will post on youtube with a link on what is happening. I took it to my buddies shop and show the master tech the video, he said to look at the throttle position sensor. Now that is about $120 - $250 4 pin 2 bolt sensor. I will see if i can get the logs and post it and check all my lines and vacuum lines as well. I am going to be cleaning the throttle body this week as well as the injectors and change out the fuel filter. I have read on other STI forms that this could be a really bad issue that may not have a fix for it. but everything has a fix, and i am not giving up on my STI.

Keep us updated!

hmbasir said:

When i get a chance i will post on youtube with a link on what is happening. I took it to my buddies shop and show the master tech the video, he said to look at the throttle position sensor. Now that is about $120 - $250 4 pin 2 bolt sensor. I will see if i can get the logs and post it and check all my lines and vacuum lines as well. I am going to be cleaning the throttle body this week as well as the injectors and change out the fuel filter. I have read on other STI forms that this could be a really bad issue that may not have a fix for it. but everything has a fix, and i am not giving up on my STI.

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Did it run like this from the factory? NO. So something is wrong and it can be fixed just like you say. It is just a matter of tracking down the culprits. Everything else is just a guess with out a log. Now I'm not saying a log will definitely show a problem because there have been many instances where a log showed nothing, but it is the best place to start because it captures the moment.

If you could, can you log the following parameters...

• Air Fuel Ratio (AFR) (A/F Sens 1 Ratio)
• Air Intake Temp
• Boost (manifold relative pressure)
• Boost Target
• Calculated Load
• Closed Loop Fuel switch (C/L Status)
• Engine Speed (RPM)
• A/F Correction
• A/F Learned
• Injector Duty Cycle
• MAF Voltage
• Throttle Position
• Waste Gate Duty Cycle
• Fuel Pump Duty
• DAM (IAM)

george

Recheck everything you might have touched from the time it was last running well and the time your started changing all the parts and problems started to occur. this would be the best course of action when diagnosing your problem. I would bet on a failing sensor or vacuum leak just based on your OP

Fuji has damn good advice on this. Work in reverse one at a time until you find the problem. This is how I solved part of my issues I had before.
Definitely get a log if you can as what holy said will be very beneficial in hopefully getting some direction.

thanks bro. you can tell i have had alot of hands on time with my own cars...you can also ask holycrapitsfast too. Ive been shooting down problems left and right with that gentleman lol...

fuji_production said:

thanks bro. you can tell i have had alot of hands on time with my own cars...you can also ask holycrapitsfast too. Ive been shooting down problems left and right with that gentleman lol...

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Credit where it's due. These cars can be a mess especially the further they are modded. A clear diagnostic path is essential prior to becoming a parts changer and throwing money at it.