Miata Mailing List: March 1997, Message #158
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   From: (none)

Subject: Re: Question to Autorotor owners...

   Date: (none)



In a message dated 97-03-01 17:57:52 EST, mspathak@worldnet.att.net (Shiv

Pathak) writes:



> From experience with all of the Bell systems, this small problems seems 

>  to manifest itself more with the autorotor and aerodyne due to the fact 

>  it achieves 5-7psi at low rpms instantly whereas the turbo spools up 

>  gradually allowing the fuel pressure to follow.  Anyone else share this 

>  opinion?



Hi Shiv,



I have an Aerodyne turbo and the boost may not come up instantly but darn

near.  I have also noticed that  the fuel pressure increase lags behind boost

pressure.  I guess that is how it must be since the FPR is boost driven.



I have to ask if you are using a J&S Safeguard knock sensor.  I bring this up

to relate a problem I had with my turbo which, within the confines of this

discussion, I believe will have similar root problems...the similarity being

that the manifold is pressurized, how it gets that way being not so

important.  Anyway,  I had a rough running condition around 3-4000rpm at low

boost for nine months.  I was continuously adjusting the base fuel pressure

in search of the elusive cure.  Nothing worked and finally, on a fluke, I

looked at the sensitivity adjustment on the J&S, which I hadn't checked since

forever.   It was turned all the way to *very sensitive* presumably in an

attempt to be in tune with the '90's.  Actually it was a holdover from before

I upgraded to an intercooler (stage II), in a successful effort to prevent

knock at 8psi boost w/o an intercooler.  I adjusted it to complete

insensitivity (real MCP stuff) and noted vast improvement in smoothness at

3-4k but some real serious pinging at full boost.  I found an nice compromise

just a little towards boorishness but near the middle of the range.

 Apparently the engine block mike would pick up some noise which the computer

interpreted as pinging and would dial back a bunch of timing.  I can't

believe I drove the car for almost 9 months that way.  



A rather wordy way of suggesting a check of the adjustment on the knock

sensor. You may have already done that in which case everything I said about

the similarities  relative to being boosted, etc., were mis-stated, wrongly

interperted, taken out of context and any other terms politicians use when

caught in a lie, and I deny it all.  ;-)



BTW, are you running the larger injectors with the stock ECU?  Could that

also be a possible cause of problems?



Insensitivity can be a good thing.



Ralph Alder

SoCal 90 Red A