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

Steve

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.

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.

Generally a good idea with any car.

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 snipped-for-privacy@motorsport.org.uk

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 imported base product with an out-of-date additive package.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 snipped-for-privacy@motorsport.org.uk

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

1. 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

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

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. ;)

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 snipped-for-privacy@motorsport.org.uk

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.

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. ;)

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

Here's the grounding thread:

Bootiful.

I'll look into it! Thanks kindly!

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.

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!!

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.

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. ;)