Hey all, you may have seen my post about my first set of mods. I have the 16% pulley reduction - my only performance mod so far. I have a question for you to see if anybody else has noticed this...

Under hard accelleration, wide open trying to use the whole of the gear, things just feel a bit rougher up from 3500/4000 onwards. I don't want to call it a yo-yo as such but just a bit of a stutter.

Sorry if I'm not describing it very well but I think if you have felt it you will know what I mean.

Thanks!!

 

if the pully is your only mod, it may be starving for air, or to much restriction on the exhaust. I've always bin a fan of the make it breath better ( intake, exhaust ) then pully.

 

That's usually why pullies and CAIs go hand in hand.

 

ohhhh thats an interesting one. I hadn't even thought of that. Thanks. Any in agreement with that or disagree?

 

Turn off the DSC and go for a ride. I find that in first and second, under WOT with a STOCK MCS I can get enough wheel spin to make it run funny.

Take out the air filter and go for a ride (on a road with out blowing sand!)
The CAI are nice, but the pressure measurments made by some people show that the air filter, not the air box is the restriction. I run my car in a class (Gstock) where I can't change the box, but I am allowed any filter. I some times run mine with a piece of window screen in place of the filter. This keeps out things that could damage the supercharger but gives me much better breathing.


J D

 

Thanks, i take the point about the wheelspin - but this is differnt to that. It is really in 3 4 5 that I notice it, that it just isnt a uniform flow of power..stuttery

 

I have the same symptoms on my car for the past 2 months...... I've got a 15% and a Pilo CAI. When running hard through the rpms there are a couple of points where the car feels like it stutters for a second, then pulls through it.
I've also got new NGK plugs..... I think the problem is ECU related. I'm still running the ECU software that came with the car new in 2004. I want to get a reflash of the JCW software next time I go to the dealer.

 

I don't know about taking your filter out if you're planning on keeping your car for a while (you know, you don't want the insides getting all dirty because of this llittle problem, especially when there's a safe way to take care of it) but, i definetly think that a cai should be your next mod. Also i agree that the dsc might have something to do with the smoothness of the power delivery (that thing is pure evil!). The dsc is more than a bit of a control freak and likes to kick in for little nothings.

 

Humm well I only have ASC and it is set to be auto-off! So I dont think that is the problem. This acts as a bump too becasue i'd love to hear any others who have noticed this.

 

Removing the air filter and going for a run is on the DO NOT DO list of things to consider. Whether or not you can see blowing sand isn't even the beginning of the issue as the naked eye can only see objects down to the 40 micron range. Engine wear and damage is primarilly caused by particles between 2 and 20 microns by some studies and 3 to 10 microns according to a GM study. A micron is .00039 inches and a hair is about 70 microns in diameter. Hence visually observing blowing sand or lack there of is not a way to judge whether or not potentially damaging particualte matter is present. Most oil filters only remove particualtes down to the 15 or possibly 10 micron range. No need in contaminating your engine oil via the air intake in order to verify that sanding the internals of an engine is generally not a good idea for longevity.

 

The JCW flash will not solve your problem because it is optomized for the slightly larger exhaust ports. I have install several MTH flashes in the last month and I am thrilled with the results. You may still see some yo-yo, but it will smooth it out.
--Dan

 

Do you think you know the symptoms that I am talking about? I wasn't sure if these were the yoyo's or if it was something different. If you think the MTH software would be a big help I'd be interested to hear more

Thanks a lot!
N