[urq] No start woes

[Gary Erickson]

On Monday, December 08, 2003, Steven wrote:

BS> ... for urq troubleshooting info get copies of the IST documents ...

Are you referring to the docs that Scott lists at:

http://www.sjmautotechnik.com/urq.html#urqman

If so, I'll drop by and bug him on the way home to see if he's got any
copies he can part with right now.

BS> I always subscribe to the "if it used to work before, check the last thing
BS> you changed" philosophy.

Agree completely.  Hence the reason that I'm climbing the walls on
this one.  Other than removing the ECU and opening the cover so Scott
could try to identify the handiwork on the modification I touched
_nothing_.

Granted, I've now dug around just about everything in trying to
troubleshoot since then!

BS> Make sure that the ECU is fully plugged into the
BS> wiring harness before doing anything else.  Are you getting any signs that
BS> the ECU is operating at all?  Can you hear the OXS Freq Valve buzzing when
BS> the key is on?

The PO had hardwired the fuel pump to "key on" (I know; I'll fix it
later rather than introducing any other issues right now).

But I have unplugged the fuel pump and left the key in the run
position a number of times now in order to trace out +12v in the
appropriate placed, etc. and never heard any noises out of the engine
bay.

BS> Have you checked the duty cycle?  Next *triple check* to
BS> make sure that you are not getting spark.  I hook my timing light up to the
BS> secondary lead from the coil to the dizzy cap and look for it to flash while
BS> I crank the engine.

I've been checking with the "spare spark plug grounded to the head"
method; but this sounds like it could be a bit easier to do with one
person.

Haven't checked the duty cycle since I didn't have any reference to
determine where to measure it.  However, if it's the OXS Freq Valve
duty cycle that you referred to above, since there's nothing buzzing,
there might not be a duty cycle to measure.

BS> If indeed you are getting no spark, probably the first
BS> thing I would check is the alignment of the crank and cam and the
BS> distributor.  When the crank is at TDC there is a mark on the distributor
BS> housing that is supposed to line up with the rotor (it may be 180deg out
BS> depending upon the crank/cam relationship, so you may have to spin the
BS> engine back around to TDC to get it to match).

Will doublecheck this when I get home tonight, but since nothing had
been touched since the car was last "gracefully shut down" I have a
feeling that everything is going to line up perfectly.

BS>   If this adjustment is out it
BS> will gate off the reference pin signal from the flywheel and you get no
BS> spark.  You might also want to check and reseat the connector to the Hall
BS> Sender on the dizzy.

BTDT about three times as I checked wiring harness continuity from the
Hall Sender plug to the ECU connector.

BS> Another one I've heard reported is a problem with the
BS> ignition key module where you lose the +12 when the key is switched to the
BS> start position ... 

Haven't checked the ECU's +12v during cranking, but I know the fuel
pump and coil are getting theirs.

The one other option that has come to light is that it's possible that
the EPROM that was installed in the ECU was corrupted or erased by
it's exposure to ambient UV light during the week that it sat around
without it's cover on.

Which would possibly explain the lack of "buzzing" from the engine
compartment with the key on.  I know it's probably a long shot, but we
are talking about a 20 year old programmable chip and I've heard of
stranger things.

Thanks for the suggestions; I'll check them out when I get home from
work tonight.

later,

-Gary

'82 ur-q
'89 200tqa
'94 S4