[Shotimes] Engine troubles

[Eric O. Angell]

On Sat, Mar 13, 2004 at 16:44:21 -0500, shojun@mtrs.org wrote:

> Your problem sounds almost exactly like the problem that my SHO had about
> a year ago.  Fixing the problem cost me about $100 (a new aftermarket DIS
> module).
> 
> My symptoms:
> -Sometimes it works fine, sometimes not.  It's a sudden jump between
> working fine and not.
> -The problem is not speed or RPM dependent.
> -The problem initially seems temperature dependent, but later you realize
> it's not.
> -When the car's working fine, the tach reads properly.
> -When the car's not working properly, the tach reads one-third low (ie,
> instead of idling at 933 rpm, the tach says you're idling at about 600
> rpm), even though you are absolutely certain that the engine is operating
> at the same RPM as it normally would (by speed and gear combination, or
> not noticing any change in RPM as the engine goes from normal operation to
> crappy operation or vice versa).  To wit, stomp the throttle, and listen
> for the butterflies opening when the tach reads 2700 rpm.
> -When the car's not working properly, you get a soft foomp-foomp-foomp
> sound from the exhaust.  The exhaust smells quite strong.  Power is
> crappy-- my car felt like my mom's old 4-cyl Jetta.  Power delivery wasn't
> as smooth as it should be, but it wasn't all that rough either.
> -Once in a while when you crank the engine, the tach takes a few moments
> to jump off of the 0 rpm after the engine has started.
> -One time while I was sitting at a stoplight, my tach started climbing
> without any reason.  It came back to 600 rpm a few moments later.
> -When you try to pull the codes from the computer, sometimes it doesn't
> give you any errors, sometimes it tells you there's a problem with the
> coil pack.  Also, while doing the cylinder balance test, it tells you that
> two cylinders have problems.

Yup, those symptoms pretty much exactly describe my problem.  As far as
some of the other emails I received go, no, the DIS isn't touching the
bracket, so I don't have any bushing problems.  Also, the explanation
that the tach is fed by spark plug firings makes a lot of sense - I'd
figured it was a crankshaft sensor, and that also explains the crappy
power if it's only running on 4 cyls instead of 6.

> parts place where I picked up an aftermarket dis module.  Swapped it in,
> and the problem never came back.

I picked up an aftermarket (Niehoff) DIS module for $120 when I was in
Denver, and that seems to have completely fixed it.  That's fantastic!
Needless to say, the drive back from Denver to LA was muuuuch nicer than
the drive up there.

Thanks a lot to everyone who provided suggestions!

-E


-- 
Eric O. Angell, eoa@cs.hmc.edu
Harvey Mudd College c/o 2004
Computer Scientist, Closet Engineer

"But why is the _rum_ gone?"
--Capt. Jack Sparrow