Need Help QUAD Driver Module(QDM)
01-04-2002, 05:04 PM
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Need Help QUAD Driver Module(QDM)
With ECM 16159278, If I remove EGR, Air Pump and EVAC Canister does the ECM need reprogramming? What are the effects of removing these items? What if I decide to keep EGR and remove EVAC and AIR what effect will that have on the PROM and stock programming?
Thanks
Ron
Thanks
Ron
01-06-2002, 02:35 PM
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Actually, just turning the flag off does not disable the EGR diagnostic. It just wont set a code when it sees the fault. The compuer will still attempt to activate the EGR and fault when it sees no corresponding change in sensor values, (up to several times per min), which can cause a very unstable idle and surging at cruise. (This is a best case scenario with an electronic EGR valve).
To disable EGR, set the minimum temp for EGR to $FD (253). The SES light will no longer turn on and no code will be set, since the engine never reaches sufficient temp to enter EGR operating mode.
On most vacuum operated EGR valves, very little checking of EGR operation is even performed in code, although some systems will at least check for correct EGR vacuum valve operation via vacuum switch.
Physically blocking off the EGR valve, without properly disabling EGR operation in code, is just asking to burn a piston on most engines that use vacuum operated EGR valves without a knock sensor.
Even with a knock sensor, performance will suffer drastically due to the spark retard resulting from the knock produced when the engine is in EGR mode (e.g. leaner A/F plus advanced timing) without the cooling and diluting effects from the exhaust gasses that are normally introduced into the combustion chamber.
IOW, knock retard recovery rate is VERY slow, so this knock induced retard will still be present even when the EGR is no longer "supposed" to be operating (at WOT for instance).
So, next time you see an EGR block off plate for sale on eBay or elsewhere, you can laugh to yourself knowing exactly what the typical fool is doing to "enhance" their cars performance ...
My advice would be to leave the systems physically intact, and just disable them in code. Then you can even re-enable them for emmisions inspections if you wish. The last thing you want is a minumum wage emmisions tech having a bad day seeing that you have intentionally removed emissions devices, since that is considered a "Federal" crime (ie.. illegal in ALL states, even if they do NOT test).
To disable EGR, set the minimum temp for EGR to $FD (253). The SES light will no longer turn on and no code will be set, since the engine never reaches sufficient temp to enter EGR operating mode.
On most vacuum operated EGR valves, very little checking of EGR operation is even performed in code, although some systems will at least check for correct EGR vacuum valve operation via vacuum switch.
Physically blocking off the EGR valve, without properly disabling EGR operation in code, is just asking to burn a piston on most engines that use vacuum operated EGR valves without a knock sensor.
Even with a knock sensor, performance will suffer drastically due to the spark retard resulting from the knock produced when the engine is in EGR mode (e.g. leaner A/F plus advanced timing) without the cooling and diluting effects from the exhaust gasses that are normally introduced into the combustion chamber.
IOW, knock retard recovery rate is VERY slow, so this knock induced retard will still be present even when the EGR is no longer "supposed" to be operating (at WOT for instance).
So, next time you see an EGR block off plate for sale on eBay or elsewhere, you can laugh to yourself knowing exactly what the typical fool is doing to "enhance" their cars performance ...
My advice would be to leave the systems physically intact, and just disable them in code. Then you can even re-enable them for emmisions inspections if you wish. The last thing you want is a minumum wage emmisions tech having a bad day seeing that you have intentionally removed emissions devices, since that is considered a "Federal" crime (ie.. illegal in ALL states, even if they do NOT test).
Last edited by mta227; 01-06-2002 at 04:17 PM.
01-06-2002, 06:26 PM
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Sorry mta227, but you are talking "way over my head" . I know you are talking to the group as a whole but I am the one experiencing this problem.. No offence -- but I am at a complete loss as to what to do next.
The service manual indicates that DTC 26 will be set when there is a fault on QDM Driver Circuit # 1. That fault according to the manual is generated by a faulty AIR Pump Relay or faulty EVAP Canister Purge and/or EGR Solenoid Valves or faulty circuits. I have remove the A.I.R. system as well as the EVAP. I am keeping my EGR for emission law(s) purposes.
Following the manual I have determined I don't have a clue whats going on!
The best I can guess is that I have an open and or grounded circuit somewhere. Yes and life sucks! The fault appears to be with the P/N indicator Position Switch or a circuit that is connected to it (no clue).
Please try to follow my logic and see if it makes any sense what-so-ever! The PNP switch, if not working properly will disable the EGR. If the EGR is disabled the QDM driver will set code 26 because it detects a fault. Where does my reasoning come from?.,, why am I stuck here??--Autoxray! It reports that my car is in first gear.... I am assuming that means that the car is NOT in Park or Neutral... That being the case., I have an open circuit at the PNP Switch or the PNP Switch is bad....
I have timed how long after starting the car it take for the code to set.. Its 20 seconds... When the code sets the fans come on -- I have no clue what that mean!
I need help here.....I am at a loss.
v/r
Ron
The service manual indicates that DTC 26 will be set when there is a fault on QDM Driver Circuit # 1. That fault according to the manual is generated by a faulty AIR Pump Relay or faulty EVAP Canister Purge and/or EGR Solenoid Valves or faulty circuits. I have remove the A.I.R. system as well as the EVAP. I am keeping my EGR for emission law(s) purposes.
Following the manual I have determined I don't have a clue whats going on!
The best I can guess is that I have an open and or grounded circuit somewhere. Yes and life sucks! The fault appears to be with the P/N indicator Position Switch or a circuit that is connected to it (no clue).
Please try to follow my logic and see if it makes any sense what-so-ever! The PNP switch, if not working properly will disable the EGR. If the EGR is disabled the QDM driver will set code 26 because it detects a fault. Where does my reasoning come from?.,, why am I stuck here??--Autoxray! It reports that my car is in first gear.... I am assuming that means that the car is NOT in Park or Neutral... That being the case., I have an open circuit at the PNP Switch or the PNP Switch is bad....
I have timed how long after starting the car it take for the code to set.. Its 20 seconds... When the code sets the fans come on -- I have no clue what that mean!
I need help here.....I am at a loss.
v/r
Ron
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01-06-2002, 08:45 PM
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Probably would have helped if you had mentioned that your problem was a quad driver fault. ;-)
Shorting that causes a fault like this can be very hard to isolate, since each driver has four circuits and any of them can be the culprit. Not to mention that irrepairable damage will usually occur to the PCM under such conditions, making it even harder to determine the original cause. Best to trace all the suspected circuits and check for shorts, then after you have found and repaired the short, try swapping to a known good PCM, while monitoring closely for any new SES codes.
I doubt that the short is located at the PNP switch, nothing to control there... its probably on the EGR solenoid circuit.
EGR vacuum solenoids are VERY suseptable to failure due to internal corrosion from moisture exposure over time, and a defective solenoid can easily cause a quad driver to fry.
None of this seems related to coding and burning eproms. Am I even in the right section?? I think somehow I may have gotten cross linked with the repair and maintenance forum. (as the Twilight Zone theme song is heard eminating from the background..)
Shorting that causes a fault like this can be very hard to isolate, since each driver has four circuits and any of them can be the culprit. Not to mention that irrepairable damage will usually occur to the PCM under such conditions, making it even harder to determine the original cause. Best to trace all the suspected circuits and check for shorts, then after you have found and repaired the short, try swapping to a known good PCM, while monitoring closely for any new SES codes.
I doubt that the short is located at the PNP switch, nothing to control there... its probably on the EGR solenoid circuit.
EGR vacuum solenoids are VERY suseptable to failure due to internal corrosion from moisture exposure over time, and a defective solenoid can easily cause a quad driver to fry.
None of this seems related to coding and burning eproms. Am I even in the right section?? I think somehow I may have gotten cross linked with the repair and maintenance forum. (as the Twilight Zone theme song is heard eminating from the background..)
Last edited by mta227; 01-06-2002 at 09:24 PM.
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