Tag Archives: iwsti.com

Fix for STI Stumble

So, there’s a thing called the ‘stumble’, where there’s a fueling issue that causes an STI engine to falter or lean-out.  In some cases, it is noticeable, especially when getting tuned.  Some tuners can tune it out while other can’t/won’t.

There are several fixes:  1) using an aftermarket fuel pressure regulator; 2) using an aftermarket fuel rail; 3) extending a fuel line.  The below links describe how to perform #3.  As well, after doing fix #3, it is advised to use Cobb’s Accesstuner (if you don’t have it, you can request it from Cobb at this link) to modify your TGV tables (as they were modified by Cobb to compensate for the stumble)…the first URL below explains how to do it.



I do plan to do this as soon as I can.  It shouldn’t take any more than 20 minutes and shouldn’t cost any more than $20 in material.   I plan to do this before I get protuned.

Note that this only affects later model STIs (2008-2014)…it does not affect the WRX or other models.

For those who think that their WRXs and STIs don’t need appropriate tires…

Here ya go!

The forum thread includes pictures.

The OP states:

was heading to work, we had just got about 3″ of snow… coming into a turn, only the car didnt turn it went straight. Took out 4 aluminum poles about 3″ in diameter concreted in the ground, which explains the right rear wheel tucking up in the body. they were some cheap a** tires that came on the car when i bought it…

Anyway ended up hitting head on with a telephone pole…

Someone asked him:

Did you have snow tires on?

And the OP stated:

… I did not have snow tires on. Probably would have been a different out come if i did.

And there it is, folks.  There are several other similar posts this winter about the same topic (someone wrecked their car because they didn’t have the right tires or were trying to get by with the summers).

Yes, I know it sucks for this guy and I’m not making light of his situation, but everyone can learn from this and spin it as a positive.