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Re: wg spring in mc turbo



In a message dated 11/23/1999 "Buchholz, Steven" 
<Steven.Buchholz@kla-tencor.com> wrote:

<< While there isn't necessarily anything wrong with putting a stiffer spring 
into the WG on an MC engine, there is one caveat to be aware of.  The way the 
system is designed, the ECU can attempt to reduce the boost using the WGFV if 
it detects knock when the timing is backed all the way down.  The benefit of 
the stiffer spring is that short bit of extra force when the turbo is 
spinning up, which will give a little bit better lag performance, but I 
wonder if anyone has actually quantified the difference. >>

I have not quantified the difference with anything but eyeballs on the boost 
gauge and seat of the pants, but here is what I have experienced.

I have the QLCC code that controls boost via the WGFV. I use this with Scott 
Mockry's 1.8 bar spring (according to Scott is very similar to the "Charlie 
Spring" which I noticed he is again offering a few remaining ones of...). 
With the O.E. spring I was not able to achieve high boost levels 
consistently. I believe this was because the O.E. spring had gone soft. 
Initially I used Scott's 1.6 bar spring (now donated to Wolff's car). While I 
was always able to achieve max boost with the 1.6 bar spring, I opted to try 
Scott's 1.8 bar version when he offered it. There is a very noticeable (and 
positive) difference between his 1.6 and 1.8 bar springs in my car running 
the same ECU code.

As far as margin of safety goes, Scott explained to me that the first line of 
defense the ECU does are three steps of fuel mapping/timing retard, then 
boost is reduced. He further explained that the WGFV is capable of pushing 
the spring back a tenth or two of a bar so that there is really not much more 
risk in running the 1.8 bar spring vs. the 1.6 bar spring. Also that the 
check engine light should blink if the ECU goes full retard and attempts to 
lower boost. (And yes, my check engine light does work because I have pulled 
codes to test it.)

This is all recollection and I am not an expert in this. Scott, and others, 
please correct me if anything I stated above is incorrect.

This all said, despite there never being any apparent timing retard, no codes 
ever set, no blinks of the check engine light, and good running 
charactoristics/performance, I have been fighting a pinging problem off and 
on for some time now. Seems to get better with some batches of fuel, worse 
with others. Seems to be at it's worst around 1.5 bar on the dash display and 
goes away at maximum boost. Gets better with fresh plugs too. I realize I am 
taking my chances and do back off if/when pinging occurs. Any advice in this 
area (aside from leaving the state of crappy gas) will be greatly 
appreciated. Note that this is a ping, not a knock, but still a valid concern 
on a boost modded engine I'm sure.

My long and wordy .02 worth...Happy Thanksgiving all!!!! (In the US at 
least...)

Mike Veglia
87 5kcstq