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Hyundai Excel Ambiguous Codes Read - continued
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 |
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Hyundai Excel Ambiguous Codes Read - continued
Further tests;
After disconnecting the negative battery terminal for 30 secs, the codes seem to be reset. The diagnostic codes are 11111111111111111... The behavior at the exhaust pipe/oxygen sensor is the same - an initial reading of 0-100Mv and no exhaust pipe smoke rising to 850-950Mv with smoking. Disconnecting the oxygen sensor does not change these symptoms and does not change the diagnostic code which is still 11111111... No overall engine warning light comes on. Why does disconnection of the oxygen sensor not change the diagnostic? Thanks for any ideas. |
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Hyundai Excel Ambiguous Codes Read - continued
wrote: > Further tests; > > After disconnecting the negative battery terminal for 30 secs, the > codes seem to be reset. The diagnostic codes are 11111111111111111... > > The behavior at the exhaust pipe/oxygen sensor is the same - an initial > reading of 0-100Mv and no exhaust pipe smoke rising to 850-950Mv with > smoking. > > Disconnecting the oxygen sensor does not change these symptoms and does > not change the diagnostic code which is still 11111111... No overall > engine warning light comes on. > > Why does disconnection of the oxygen sensor not change the diagnostic? > > Thanks for any ideas. ============= ============= Put a new PCM in the car. ~:~ MarshMonster ~:~ |
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Hyundai Excel Ambiguous Codes Read - continued
> > Put a new PCM in the car. > Do you mean PCM as in the following; "2002 Hyundai XG350 Even though a cable is connected to the accelerator pedal, this vehicle is drive-by-wire. The cable leads to a pedal position sensor under the hood, and the powertrain control module (PCM) operates the throttle." I can't find any reference to a PCM in the Haynes manual, however the following components are described; Fuel rail and injectors Fuel pressure regulator Throttle position sensor ECM Idle speed control actuator Air flow sensor Engine coolant Temperature sensor Intake air temperature sensor Crankshaft position sensorMFI control relay Vehicle speed sensor Oxygen sensor This is a 91 Hyundai Excel - would it have one? Any suggestions on what its function is or where to find it? Any suggestions regarding those other components? Tkx |
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Hyundai Excel Ambiguous Codes Read - continued
Consider the PCM to be the same as the ECM.
Powertrain Control Module versus Engine Control Module... |
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Hyundai Excel Ambiguous Codes Read - continued
Is there some conclusive test for an ECM failure?
Is there something significant in the car's behavior that I described or are these units prone to failure? The following is originally from a vendor forum, I think. "...But, I have to ask, if you drove your car to the dealer with this problem what part of the computer failed? My experience with bad computers is really bad, as in you can hardly get anywhere with the vehicle. Or you just can't get anywhere. Car computers are real tough pieces of silicone. I've seen wiring harnesses melted together and after the repair the computer shook itself and went back to work...." Are there some other steps that I can go through to test the sub-components and rule out a simpler problem? What are the likely sources, given the symptoms or are there no other possible explanations? Thanks |
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Hyundai Excel Ambiguous Codes Read - continued
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Hyundai Excel Ambiguous Codes Read - continued
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Hyundai Excel Ambiguous Codes Read - continued
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/ ------------------------- 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 > |
#10
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Hyundai Excel Ambiguous Codes Read - continued
Thank-you all for you help so far. Until I read Stephen's post, I would
have assumed the MAF sensor for the reasons below - now I feel I should, test or replace the ground splice. MAF Tests I performed the MAF tests in Haynes 4-24 (Air Flow Sensor 1994 and earlier) Output voltage of the sensor when disconnected between pins 3, 6 should be 2.7-3.2 V (was .15-.03V). Voltage between pins 5,6 should decrease when air intake is obstructed - it was 0V. The codes shown after this test with MAF disconnected are 2,5 - Baro pressure sensor 1,2 - Airflow sensor 1,5 - Motor position sensor Is this a good enough indication that the MAF has failed? ECU Resetting the ECU and disconnecting the coolant temperature sensor for a general test of the diagnostic fcn of the ECU produces 1,5 - Motor position sensor I guess the ECU is not meant to be interpreted by mugles :> Ground Is there any good test of the bad ground theory - such as connecting the test ground on the ECU to the negative battery or the block with a good thick conductor and seeing if the problem disappears or looking for a voltage W.R.T. ground on the ECU test ground? Thanks again for all the help - I'm proceeding with MAF replacement. |
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