I'm experiencing a really odd problem with my '06 STI that recently started and happens pretty much every day - but not every time I drive it. When running at WOT it seems like it's not opening up. When I get on it, it hesitates, surges, and never really gets going at top end. To the tune of what feels like 40-50 less horsepower. Torque seems fine - it's just not getting into the power band at higher revs. That said it does feel like it hesitates at low speeds in parking lots, etc. I seriously believe my Toyota Sienna could take it in the quarter mile when it's acting up. My filter is clean and lightly oiled, I cleaned my MAF, and I've started putting a different brand of gas in it. My engine is completely stock except for a drop-in K&N filter. I had to have my rear diff replaced...my drivetrain still clunks a lot when on/off the throttle in traffic. It almost seems like a drivetrain drag issue bogging down the engine but I suspect if it was it'd happen all the time. From what I've read it seems like it could possibly be a vacuum leak that others have experienced....it also seems like the problem '07 STIs have hesitating/surging problems. Perhaps the fuel filter or spark plugs? It happened on the way home yesterday evening (fairly humid and 81 degrees)...but ran like a champ this morning as it does 30-40% of the time regardless of temp or humidity. Any ideas what this could be??
Did you check all the hoses/clamps from turbo to IC to throttle body? Double check them, especially underneath where you can't see. What max boost are you making on boost gauge? The clunk is probably not your diff but the bushings in the bracket that holds it. Mine does the same. There is a "clunk killer" kit that TIC sells: http://www.turninconcepts.com/product_info.php?cPath=1_9_11_259_1251_1253&products_id=24 That link is for the '04 like mine, there is a kit for '06 also.
BTW, I don't have a boost gauge - completely stock. 8-o Maybe one of these days! Thanks for the link to the clunk killer...that's very annoying.
yeah i know coil packs go bad, and apparently are a common problem. not sure on the maf, but i assume so.
07s were ecu problems, what you have is prob mechanical. and please do get a boost and oil gauge. srsly, it's a turbo car.
you should defenately bring it in and let us look at it. only thing is that the warrenty is 3yr-36k bumper to bumper and 5yr-60k power train. the problem may not be covered under warrenty.
Shucks...forgot about that. Still needs to be fixed... I'd like to try cleaning my MAF again --- is throttle body cleaner what I should be looking for or is there something specific to MAFs? Any chance a bad spark plug could be causing this?
I would think that if it were a plug or coilpack you would be feeling/experiencing some sort of misfiring or other detonation issue? That's why I suggested the MAF. The cleaner isnt really brand specific, just go out there and find "maf cleaner" at your local auto parts store
I used electronic cleaner from Radio Shack. But if you cleaned it already, I mean it's either visibly dirty or not. Your air filter is clean?
I used throttle body/intake cleaner that was safe of O2 sensors - I'm going to give everything a good check/cleaning this evening and see what happens.
I've been waiting a few days so I could get a good read on the fix before I re-posted. I cleaned my MAF again (with Radio Shack electronics cleaner like 2thAche) and went ahead and cleaned my filter as well (although it wasn't too dirty). She's running like a charm - actually like I never remember. What a difference. I suppose it was something dirty in the intake. Fingers crossed she'll stay that way. Thanks for your feedback everyone!
Intake was dirty and dirtied up the ol' MAF. This has to be about the 20th time this has come up this summer. For whatever reason MAFs seem to go bad/dirty this time of year. Either that or everyone is simply driving more (another possibility).
What's your mileage? At 75K I suffered from the same issues and had about 5 boost leaks ,2 vacuum leaks, a bad BOV and an exhaust leak. If your going to keep it stock I would still get it tuned from what I have heard the factory tunes are pretty worthless.
Hmm not too much, although, I have an 02 bugeye. The hoses seem to go quick and the connections(clamps) come loose on these cars, especially if you drive them hard often.
Interestingly, every now and then I can feel the hesitation coming on when I get on it. Like something's still not quite right...keeping fingers crossed!
THAT could very well be a coilpack they are usually more noticeable (at least in my eperience) in the higher RPMs and when your at WOT
I've given this some time to make sure I wasn't going to experience the placebo effect that cleaning my MAF and air filter brought on. I finally found the problem causing the sluggishness and hesitation with my STI - spark plugs! Yep, at 49,000 miles 4 new plugs did the trick. It was easily a 30 horsepower gain...no kidding. My car was a complete dog before, especially now that I see how it can run. This is one of those things that can creep in slowly so you won't realize it much over time. If you're in doubt change those plugs! Worked wonders for me...