Here are a post or two from a tech service I subscribe to; The common thing
I noticed is bad grounds to and sor the computer and bad computers.
Good luck
--
Stephen W. Hansen
ASE Certified Master Automobile Technician
ASE Automobile Advanced Engine Performance
ASE Undercar Specialist
http://autorepair.about.com/cs/troub...l_obd_main.htm
http://www.troublecodes.net/technical/
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Hi Group, Took over a month to get this vehicle back to the
shop for the fix. There is a technical service bulletin
pertaining to this very problem that involves repairing the
ground wire splice inside the main engine harness. Paul
Baldassarre of Hyundai suggested bulletin # 93-36-007-1. We
repaired the wire splice and the vehicle has over 500 miles
with no complaint of a check engine light or power loss. Also,
thanks to
------------------------
I believe I'm chassing the illusive ground problem... As an
IMPORTANT NOTE: This vehicle has been wrecked in the front end
& repaired with somewhat questionable quality.
All these codes & no MAF or CTS readings. Bevus & Butthead's
Stereo Shop installed an alarm - wiring not effecting this
situation, but we feel they leaned on the MAF plug & damaged
the MAF and or plug because we could get readings when we
wiggled the connector. Tighteneing contacts didn't helt, so we
replaced the MAF (rebuilt), and the connector - same problem.
I found & tightened several grounds under the hood, but don't
know if I've found them all - no help. Cleaned the throttle
body for the code 15 - no help.
The snap-on scanner said up front that codes 12,13,15,25 at
the same time mean bad maf connection.
Replaced cts - no help. Another thing I noticed is that I
loose ground to my scanner when I'm wrigling the MAF connector
(it goes to the 'no communication' frame. Are they the same
ground?
___________________ TEST AND REPAIR DATA ___________________
COMPUTER CODES AND DESCRIPTIONS
12 - MAF problem 13 - IAT problem 15 - IAC out of range 21 -
CTS out of range 25 - Baro pressure sensor circuit problem
____________________________ FIX ___________________________
Only two replies. It was suggested that bad grounds were the
main problem. Re-established grounds. Ran much better. Found
that 'Bevis' had jerked around the throttle stop to accomodate
for the poor idle. Re-adjusted stop and car runs great. Many
Thanks, John
> wrote in message
oups.com...
> This is a continuation of a post with the same name. Briefly, the 91
> Hyundai Excel I own idles roughly and smokes sometimes even though it
> seems mechanically OK (cylinder pressure within spec).
>
> I am hoping COMBOVERFISH responds to this post as he was absolutly
> right in suggesting a multimeter would show a trouble code when a scope
> did not. After the last post, I replaced the oxygen sensor and the
> symptoms are similar.
>
> Diagnostic Codes
> 1 2 5 2 5 2 5 2 5 ... which I take to mean Barometric pressure sensor.
> So far I have no idea where this is or how to test it.
>
> Oxygen Sensor
> I replaced the sensor although a good ground may have prevented me from
> detecting that the old one was working. In any case the behavior is
> unchanged. On warm start, I measure between 150-300 Mv initially. After
> 5 minutes the signal has increased to the range 890-1000 Mv. The engine
> idles roughly and when accelerated, smokes. Unhooking the oxygen sensor
> seems to produce no change in the smoking behavior or the oxygen sensor
> reading.
>
> Am I reading the codes correctly and what is the barometric pressure
> sensor?
> Is it possible that the oxygen sensor is not connected to the ECM?
> Any suggestions happily accepted.
> Thanks
>