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Old 12-16-2008, 01:53 PM   #1
qstarin
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Member#: 186129
Join Date: Aug 2008
Chapter/Region: MWSOC
Location: Minneapolis, MN
Vehicle:
2001 2.5RS
STM

Default Bog at 80% throttle & 3800 RPM in 4th gear (01 RS)?

Car is 2001 2.5RS (NA) mostly stock except SPT intake and swap from auto tranny to 5MT and a bunch of suspension stuff.



I was on my way to work and dropped into 4th to pass someone.

I got a slight, but definitely noticeable, boggy hesitation right at 3800 RPM and maybe 80% throttle. As soon as the tach hit 4000 RPM the bog went away and it pulled like normal.


Intrigued - I tried it again and was able to reproduce it at will. 3800 RPM & anything upwards of about 70% throttle produces the slight boggy hesitation in 4th gear.

Tried to do it in 2nd & 3rd gear and it didn't seem to be happening - of course, it goes from 3800 to 4000 RPM much more quickly, so maybe it isn't there long enough or is related to engine load? Also, my road wasn't totally clear, so I really wasn't able to WOT it in 2nd or third at that RPM to test.


Any ideas why I might be getting this bog? I seem to have been getting weird coming and going bogs around this RPM in 4th and near WOT since my tranny swap. It's been infrequent enough, though, to not really worry too much about.

Is this near the closed/open loop switch over? Could I have fubar'd my O2 sensor a bit (have taken my exhaust off a few times here now)? Anything else it could be?

Are there any systematic tests I could try to narrow it down as to what it might be?


Coil pack is one year old, as are plug wires. Plugs are a few months old (when I Seafoamed it) - but I did have a HG go since then. Caught it quickly and replaced both sides with STi HG's.


Any help is greatly appreciated!
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Old 12-16-2008, 02:06 PM   #2
yarrgh
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Join Date: Jan 2005
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Location: Aurora, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

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if it's stock, why replace with different head gaskets?
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Old 12-16-2008, 02:26 PM   #3
qstarin
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2001 2.5RS
STM

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One blew out.

I wasn't aware at the time that they changed the OE ones for the NA EJ25's to a multi-layer - thought they were the same faulty ones that they came with originally, so I got the STi ones based on what I read saying that they were compatible and wouldn't have the same problems blowing out that the original single layer ones did.

I'd be surprised if the fact that I put STi HG's in is related to this bog, though. But I really don't know much.
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Old 12-16-2008, 11:43 PM   #4
Storm
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Developed Beater

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80-ish % is the crossover from closed to open loop or vice versa. There is a known glitchyness associated with it from less than perfect grounds and even ECU versions. IIRC, for an 01, you can have the dealer flash a revision for this hesitation. I would still check all your grounds though.

Jay
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Old 12-17-2008, 01:43 AM   #5
qstarin
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STM

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Well, I'm getting an i-Speed reflash within a week - so I'll get to test if its the closed/open transition - if it goes away when I install the flashed ECU I'll assume its the crappy stock tune.

As for grounding - I'm good. Got a huge stereo and I've already beefed up all my wiring.
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Old 12-17-2008, 07:47 AM   #6
Storm
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Unless your connections are not good. That's why I said check them......not replace them.....
Quote:
Originally Posted by qstarin View Post
As for grounding - I'm good. Got a huge stereo and I've already beefed up all my wiring.
Jay
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Old 12-17-2008, 11:40 AM   #7
qstarin
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Location: Minneapolis, MN
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2001 2.5RS
STM

Default

Quote:
Originally Posted by Storm View Post
Unless your connections are not good. That's why I said check them......not replace them.....

Jay

My grounds are good.

I'm obsessive about my wiring. Like seriously - pre & post winter I pretty much check, clean, and protect every connector and wire in the engine bay - I do it right after I clean and degrease the engine bay. If a ground is showing rust I sand it off, reconnect, and slather it up with dielectric grease. I also reapply grease to several spots throughout the winter as it washes away.

Last edited by qstarin; 12-17-2008 at 11:46 AM.
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