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Re: Throwout Bearings & interlocks

To: sol <british-cars@autox.team.net>
Subject: Re: Throwout Bearings & interlocks
From: Randy Wilson <randy@taylor.wyvern.com>
Date: Thu, 27 Jan 1994 00:30:33 -0500 (EST)
Various people wrote parts of:
> >  
> > > "effects of legislative and litigious idiocy". The "must step on clutch"
> > > idea was a reaction to the Audi 5000 lies about unintended acceleration.
> > 
> > No way.  My 1976 Chev pickup had a "must step on clutch" interlock.
> > 

Yep, Ameribarges have had clutch interlocks for a long time. Most foreign did
not, until the Audi incident. Now most every econobox has one.

> 
> Actually, there was a bit more to it than that. (in my opinion)
> 
> I have done a bit of research on K-Jetronic FI systems, like those I believe
> the cars in question used, and I have come to this conclusion:

Not just K/KE. The first idle comp systems appeared on L-Jet in 1980. It 
migrated to other systems. K/KE was the last of the Bosch types to get it,
about 85. Not all of the Audi's affected by this "complaint" had it. BTW,
I think it is now safe to catagoricly say that all cars have idle comp
systems. (Even my race cars have one, but that's a story for w2w).

>       The KE-Jet system has an (optional?) electronic box that functions only
> to maintain a constant idle by supplying more air past the throttle plates, 
>no 
> matter what the load. (ie: auto trans in "D"; A/C compressor enguaging, etc.) 
> The K-Jet and KE-Jet systems have a cold-start injector, and supplementary air
> bypass valve, the latter of which funtions for 10-30 seconds. (depending on 
>air
> temp, and application) This is the equivalant of a fast idle cam in an 
>American

Uh, no. About the same time the idle comp was added, the coldstart and aux air
regulator became history. May have been a *few* years with both, but I don't
think so.

> car lurches _slightly_. Now imagine the same circumstances, but with a 
>constant
> idle box trying to raise the idle back up to where it was before being dropped
> into gear! -SCREEEEEEECH!- If the car is idling high enough when cold, this 
>may
> be a problem with _any_ KE-Jet equipped vehicle. Maybe Audi just had their 
>cold
> idle a bit too high, or maybe they have a lower "stall speed" on their torque
> convertors, either of one can cause exactly those results.
> 
This, I can say for sure, is wrong. The idle comp system aims for a constant,
absolute, idle speed, not a relative one. Typically, four cylinders are set at
740 rpm. If you do have one with both an idle comp and an aux air regulator,
the aux will attempt to bring the idle up to around 900-1000 rpm, when stone 
cold The idle comp will attempt to bring it back down, ending up closed all the
way. The idle would end up arounsd 850-900. This is why they trashed the aux air
reg. The idle comp system actually monitors engine temp and a few other
parameters (a/c, starter, trans, etc) and does a damn good job of picking
a setting.
 Also, the idle comp valve air passage is *small*. The Bosch valves only
flow enough at max open to raise the idle 500 rpm or so. Definately no 
"SCREEEEEECH" here.

 This is getting long enough, considering the total lack of lcb content, well
the XJ-40 does have this sytem, but  would like to say one thing on the Audi
bash. During the height of the controversy, I many times had to calm
worried Audi owning customers. I'd take them out on a back street, lock the
trans in low, and floor it. At about 4K rpm, I'd reach over with my left foot,
and *normally* press the brakes; gas still matted. In every case, even the
turbo's, the brakes won the battle hands down. There's no question in my
mind about which peddle the "victims" were standing on.

   Randy
     randy@taylor.wyvern.com


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