Turbo 'shudder' in 02 WRX.

The closest thing to what you have described that I have experienced ('02
WRX 78k mi) is waste gate flutter. It is most noticeable in 3rd and 4th with
just moderate boost-- I think it is the loudest if I hold boost at -.05mpa.
At times in my car it can be very loud and at others it is not noticeable at
all. Check out some of the forums at www.nasioc.com there were some
discussions when I looked up my noise last year.

Steve

"BD" wrote in message

> Hey, all.
>
> I have about 40,000 km on my 02 WRX. I use the turbo fairly rarely, and
> I always wind it down after each drive by keeping the car under 3000
> rpm for several blocks before parking.
>
> I also (almost) never bring the engine above 3000 rpm until it's fully
> warmed up (ie the temp gauge has settled at its normal running level).
>
> Sometimes I notice that when I do kick in the turbo (usually in 3rd or
> 4th), the motor seems to shudder very slightly. This effect is subtle,
> and temporary. I can usually make it stop by gearing down and really
> forking the turbo for a few seconds (ie ~5000-6000rpm). It's almost
> like it has to clear its throat before it starts to sing.
>
> I guess it could be just the motor at the higher revs as opposed to the
> turbo - I'm not a gearhead, so I don't know.
>
> I mentioned it to the dealer at the last service time, and they could
> find nothing amiss. They suggested trying 94 octane gas instead of my
> usual 91.
>
> Has anyone seen this kind of behavior? Any comments?
>
> Thanks,
>
> BD
>
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

BD wrote:

> Hey, all.
>
> I have about 40,000 km on my 02 WRX. I use the turbo fairly rarely, and
> I always wind it down after each drive by keeping the car under 3000
> rpm for several blocks before parking.

The turbo is always spinning whether or not there's any boost.
Although the turbo's water cooling helps reduce the bearing temps
at shutoff, even "under 3000 rpm" may not be ideal.

The ideal situation is to let the turbo spin down to the lowest
speed, and allow active oil/water cooling to bring the turbo temp
as far down as possible. This means idling it. The revs may not
even be that good an indicator, since the turbo is driven by
exhaust pressure. The turbo might be spinning faster at 2000
RPM on an incline than at 2500 RPM on level ground.

I don't get obsessive over the cool down period. However - I
slowly back my car into my garage on an incline in neutral. The
typical time it takes is about 30-40 seconds, especially since
I'm waiting for the automatic garage door opener.

> I also (almost) never bring the engine above 3000 rpm until it's fully
> warmed up (ie the temp gauge has settled at its normal running level).

Generally a good idea with any car.
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

On 24 Jan 2006 14:29:03 -0800, "BD" wrote:

>I have about 40,000 km on my 02 WRX. I use the turbo fairly rarely, and
>I always wind it down after each drive by keeping the car under 3000
>rpm for several blocks before parking.
>
>I also (almost) never bring the engine above 3000 rpm until it's fully
>warmed up (ie the temp gauge has settled at its normal running level).
>
>Sometimes I notice that when I do kick in the turbo (usually in 3rd or
>4th), the motor seems to shudder very slightly. This effect is subtle,
>and temporary. I can usually make it stop by gearing down and really
>forking the turbo for a few seconds (ie ~5000-6000rpm). It's almost
>like it has to clear its throat before it starts to sing.
>
>I guess it could be just the motor at the higher revs as opposed to the
>turbo - I'm not a gearhead, so I don't know.
>
>I mentioned it to the dealer at the last service time, and they could
>find nothing amiss. They suggested trying 94 octane gas instead of my
>usual 91.

1. Yes, you should be using the higher octane fuel in a Rex.

2. You should be using a high quality branded fuel from one of the
majors with an advanced detergent package.

3. You should be driving the car as it was intended to be used, not
dawdling about at low revs most of the time.

Your car is suffering from a poor diet and lack of exercise.

David Betts
davidb.TakeThisOut@motorsport.org.uk
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

> Your car is suffering from a poor diet and lack of exercise.

Nice way to put it.

I normally use PetroCan (Canadian stuff) or Chevron, both 91. Heard BAD
things about Shell and Esso
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

>The additive package used will vary from market to market, but you would certainly expect Shell to be amongst the best anywhere in the world.

Was it not Shell who faced that class-action lawsuit some years back
for their additives damaging engine parts? Either Shell or Esso, I
forget.

Regardless - the strongest recommendation I get here is for Chevron's
94. I'll try that for the next few tanks, and take the car out for a
nice throat cleaning. My time for 'fun' driving has been pretty tight
as of late...

BD
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

On 25 Jan 2006 08:38:42 -0800, "BD" wrote:

>> Your car is suffering from a poor diet and lack of exercise.
>
>Nice way to put it.
>
>I normally use PetroCan (Canadian stuff) or Chevron, both 91. Heard BAD
>things about Shell and Esso

Interesting. The additive package used will vary from market to
market, but you would certainly expect Shell to be amongst the best
anywhere in the world. They are the world leaders in fuel and
lubricant development. Texcaco is my second choice in the UK. Exxon
tend to market more on price than quality, but should still be pretty
good. Goodness knows what your 'Canadian stuff' is really. Probably
cheap. imported base product with an out-of-date additive package.

David Betts
davidb RemoveThis @motorsport.org.uk
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

Hi Bobby!

On 24 Jan 2006 14:29:03 -0800, "BD" wrote:


>Has anyone seen this kind of behavior? Any comments?

The early WRX's were notorious for grounding problems in the engine
compartment; symptoms similar to what you're describing, hesitation on
acceleration, "stuttering" sensation, . . .

Might not make any difference at all, but certainly cheap enough to
try. Details for this mod readily available on line (Soobiemods,
NASIOC, USMB, etc.) or I've even seen kits to do it on ebay for around
$50.

Another thing I've noticed is that the cars ECU "learns" your driving
habits (seriously!), and will go into an "economode" if the car isn't
being driven fairly aggressively. Seems to take a couple determined
runs thru the power band before the ECU realizes you're serious and
gets with the program. When I was autocrossing mine, I would reset the
ECU by disconnecting the negative battery terminal for a minute before
starting my runs; this made a huge difference. (Note that _any_ change
that you can readily feel "seat-of-your-pants" vs observe on a dyno,
or thru et's on a drag strip, is a "huge" change . . .)

Hope this helps a bit.

ByeBye! S.

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

>Might not make any difference at all

Sounds like it's worth looking at - but I'm not clear on what the
suggestion is here;l there's some cheap-ish mod kit that I can put in
to fix a grounding problem? Is there a name for this kit, or should I
just hit up nasioc for 'grounding' and find it that way...

As to the ECU - that's interesting. I had no idea.

I think it's time for me to skirt the red line on this baby for a
while.
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

On 25 Jan 2006 09:28:12 -0800, "BD" wrote:

>>The additive package used will vary from market to market, but you would
>>certainly expect Shell to be amongst the best anywhere in the world.
>
>Was it not Shell who faced that class-action lawsuit some years back
>for their additives damaging engine parts? Either Shell or Esso, I
>forget.

Many years back Shell had a problem with a potassium additive package
developed for unleaded fuel causing sticking valves when used in
leaded fuel in certain cars under severe weather conditions. Very
difficult to pin down, because it only occurred in very specific
circumstances.( ie cars with particularly tight valve tolerances which
were subject to extreme use in very cold weather.) Nevertheless, Shell
withdrew the product and took their knocks. Sometimes these things
happen when you try and give the customer the best possible product.
Hardly a reason for not buying Shell now. After all, if it's good
enough for Ferrari....

David Betts
davidb.RemoveThis@motorsport.org.uk
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

> I believe its one of the stickys or it is in the cheapest way to mod your WRX thread.

Uh... wut?

I gather that the site has something called a 'sticky', and that
there's a forum thread called 'cheapest way to mod your WRX' ???

Appreciate the help, but a little more punctuation would be helpful
too.
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

BD wrote:
>> Might not make any difference at all
>
> Sounds like it's worth looking at - but I'm not clear on what the
> suggestion is here;l there's some cheap-ish mod kit that I can put in
> to fix a grounding problem? Is there a name for this kit, or should I
> just hit up nasioc for 'grounding' and find it that way...
>
> As to the ECU - that's interesting. I had no idea.
>
> I think it's time for me to skirt the red line on this baby for a
> while.
>

I believe its one of the stickys or it is in the cheapest way to mod
your WRX thread. I've been suspicious about this, just seemed to be to
good. I've got a 2003 WRX and I've noticed some inconsistent
acceleration even after the motor has warmed up. I've been debating do
this, but I may revisit.
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

>Here's the grounding thread:

Bootiful.

I'll look into it! Thanks kindly!
 >> Stay informed about: Turbo 'shudder' in 02 WRX. 

Interesting.

I'm not yet convinced my problems haven't gone away with the 94 octane
gas - but if not, I'll look into it!

Thanks!!
 >> Stay informed about: Turbo 'shudder' in 02 WRX.