Turbo 'shudder' in 02 WRX.

[BD]

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

 

[SuperPoo]

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]

waste gate flutter.

Thanks, I'll check out nasioc.

However, the symptom I'm experiencing is not audible at all - it's an
inconsistency in the acceleration, which I can feel as I spin up.

But, the conditions seem similar, so there could be some connection...

Cheers,

BD.

 

[y_p_w]

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.

 

[David Betts]

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
(e-mail address removed)

 

[BD]

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

 

[David Betts]

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
(e-mail address removed)

 

[BD]

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

 

[S]

Hi Bobby!

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

 

[BD]

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.

 

[David Betts]

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
(e-mail address removed)

 

[Theodrake]

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.

 

[BD]

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.

 

[Theodrake]

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.

http://forums.nasioc.com/forums/forumdisplay.php?f=37
NASIOC - Factory 2.0L Turbo Powertrain

Notice the first three threads say - Stick: <subject>

First one to read is: "Sticky: FAQ and Threads of Note- Read me first!"

 

[Theodrake]

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.

Here's the grounding thread:


http://forums.nasioc.com/forums/showthread.php?s=&threadid=156303
NASIOC - Grounding Mod thread.

 

[BD]

Here's the grounding thread:

Bootiful.

I'll look into it! Thanks kindly!

 

[capnned]

Hi Bobby!



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.

Rather than go off and buy a grounding kit, you can easily improve the
grounding by simply making sure there's bright paint-free steel under
the bolts holding down the chassis grounding wires. There's one on
each side by the strut tower and a much more difficult-to-reach one on
the firewall. Clear out the paint, buff up the steel a bit, slap on
some dielectric grease and you've accomplished all that the mod kits
do at the price of 20 minutes under the hood and a $1.49 tube of
dielectric grease.

I did this on my '02 WRX and my part-throttle stumbling issues
disappeared.

 

[BD]

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!!

 

[Uzi]

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.

I tried it out after reading this thread. I took a length of #10 wire
and ran it from the negative post to the closest intake bolt. It is a
temporary job, but I noticed my 2002 WRX ran quite a bit smoother than
it did before. I hadn't noticed that there was a hesitation until now
that it is missing.

 

[BD]

That's fascinating.

I'd love to do this myself, but I'm unfortunately not familiar enough
with the placement of parts on my vehicle to know exactly where you ran
from. Call me - intelligent but uneducated. ;-) Negative post on the
battery, then?

Do you know of any after-market maintenance manuals that could describe
exactly where you ran the wire? I know my dealer was supposed to supply
me with a maintenance manual, but never has - assuming the stock
maintenance docs would tell me what I need to know here.