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11 Posts
Dear Members,
I am a hyundai Technician and have been with the company just over three years. I own a 2009 Hyundai Accent 4 door GLS. Over the past few weeks I have noticed an evasive missfire that only occurs on cylinder two. ( P0300-and P0302) and it occurs sometimes first in the morning, or 1/2 to 1 hour hot soaks. subsequent start ups it does not occur. the vehicle will start, miss, MIL will flash, then PCM cuts fuel and its just a dead miss. other times it will correct after a few seconds and resume normal operation. Once cleared, the issue does not occur while driving. Under any load.
Of course I have searched for common Accent headache items. I checked fuel pressure which was ideal. The coil was swapped coil 2 to 1 and 1 to 2. The spark plugs were changed with OEM and gap as .040- .044 thousandths as hyundai spec. I also swapped injector 2 to injector 1 and 1 to 2 to rule out a sticky injector. All these steps did not correct the issue. Misfire still and only on cylinder two.
Today I inspected engine vacuum and compression to verify proper sealing. Compression was at or very close to 200 psi. Hyundai spec is 185-214 give or take with a variance of 14 psi per cylinder. Engine vacuum was a solid 17-18 inHg with no flutter. Although I did not check during the miss event.
So techs, my next move is to the harness. I viewed hyundais ETM electrical diagrams and found that my injectors are low side driven by the PCM. So to verify cylinder two was receiving PWM from the PCM I wrote down my pins and attempted to jump the injector to PCM controlled ground. However Hyundai in there infinite wisdom supplied me with a PCM diagram from a M-trans car even with a VIN lookup......
SO this week I have found the correct PIN locations and will try to attempt a harness bypass one more time. I am skeptical its the harness because it does not occur while driving. My last synopsis is a possible ECM failure, which back-probing the connector should outline. IF anyone has any suggestions I am happy to hear!!
I did call Hyundai Techline and they just said good luck if its not coils or compression it probably needs a head due to valving issues, but my vacuum is rock solid. Thanks again!!! HyundaiTech2294 Andrew
ALSO: My MAP sesnor through Hyundai GDS is reading 10 InHg, while the vacuum guage is reading 18-19 InHg. and with increased engine load, foot on brake, accelerator depressed ( stall test) The MAP vac INCREASES to 15-16 InHg, while voltage rises from aprox 1 volt to 3.5-3.8. The voltage is correct, high vacuum low voltage, low vacuum, higher voltage. At least with most manufacturers. Is this a GDS Hickup? Manifold vacuum should DECREASE with engine load. Other than this there is no troublesome PID values.
I am a hyundai Technician and have been with the company just over three years. I own a 2009 Hyundai Accent 4 door GLS. Over the past few weeks I have noticed an evasive missfire that only occurs on cylinder two. ( P0300-and P0302) and it occurs sometimes first in the morning, or 1/2 to 1 hour hot soaks. subsequent start ups it does not occur. the vehicle will start, miss, MIL will flash, then PCM cuts fuel and its just a dead miss. other times it will correct after a few seconds and resume normal operation. Once cleared, the issue does not occur while driving. Under any load.
Of course I have searched for common Accent headache items. I checked fuel pressure which was ideal. The coil was swapped coil 2 to 1 and 1 to 2. The spark plugs were changed with OEM and gap as .040- .044 thousandths as hyundai spec. I also swapped injector 2 to injector 1 and 1 to 2 to rule out a sticky injector. All these steps did not correct the issue. Misfire still and only on cylinder two.
Today I inspected engine vacuum and compression to verify proper sealing. Compression was at or very close to 200 psi. Hyundai spec is 185-214 give or take with a variance of 14 psi per cylinder. Engine vacuum was a solid 17-18 inHg with no flutter. Although I did not check during the miss event.
So techs, my next move is to the harness. I viewed hyundais ETM electrical diagrams and found that my injectors are low side driven by the PCM. So to verify cylinder two was receiving PWM from the PCM I wrote down my pins and attempted to jump the injector to PCM controlled ground. However Hyundai in there infinite wisdom supplied me with a PCM diagram from a M-trans car even with a VIN lookup......
SO this week I have found the correct PIN locations and will try to attempt a harness bypass one more time. I am skeptical its the harness because it does not occur while driving. My last synopsis is a possible ECM failure, which back-probing the connector should outline. IF anyone has any suggestions I am happy to hear!!
I did call Hyundai Techline and they just said good luck if its not coils or compression it probably needs a head due to valving issues, but my vacuum is rock solid. Thanks again!!! HyundaiTech2294 Andrew
ALSO: My MAP sesnor through Hyundai GDS is reading 10 InHg, while the vacuum guage is reading 18-19 InHg. and with increased engine load, foot on brake, accelerator depressed ( stall test) The MAP vac INCREASES to 15-16 InHg, while voltage rises from aprox 1 volt to 3.5-3.8. The voltage is correct, high vacuum low voltage, low vacuum, higher voltage. At least with most manufacturers. Is this a GDS Hickup? Manifold vacuum should DECREASE with engine load. Other than this there is no troublesome PID values.