The Problem
My car runs fine until the engine warms up; i.e. when the radiator fan comes on. Once warm, it idles steadily at 500RPMs but will intermittently stumble, maybe once or twice every 5 minutes, sometimes not at all. With the motor warm, if I try to rapidly go to Wide Open Throttle (WOT) the motor will stumble as the RPMs increase. Sometimes, the stumbling is really bad and the motor doesn't make it past 1000RPMs, it just stalls out. If the motor makes it past 1000RPMs, the stumbling continues and actually keeps the car from passing 3500RPMs; it just bounces between 3500RPMs and 3250RPMs. While in the 3250-3500RPM zone, if I let up on the throttle slightly, the stumbling disappears and the motor smoothly sails to redline without fail. Releasing the throttle slightly before the 3250-3500RPM zone does not prevent stumbling in the motor's approach to higher RPMs.
My Car
1997 Honda Accord EX-V6 sedan with the C27A4. The C27A4 uses mulit-point Programmed Fuel Injection (PGM-Fi) running On-Board Diagnostics standard 2 (OBD-II). I've got 226732 miles on the body and motor. All stock in the engine bay. I have a 4-speed automatic transmission. I stay on top of all maintenance, and perform all work myself.
Recent History
In the past year, the only unresolved Check Engine Light (CEL) I have gotten was 67: P0420 Catalyst System Efficiency Below Threashold. I've cleared it twice but have not gotten around to finding the cause. I have noticed in the last 3 months my exhaust has taken on a gassy smell which has progressively gotten stronger over those three months. It is as if the amount of unburnt fuel in my exhaust keeps increasing.
Florida doesn't have emissions testing and the catalytic converter was replaced in June 2009 with a Magnaflow OEM Replacement; I destroyed the original by leaving a ground wire loose which caused an intermittent power failure in the ECU which lead to backfiring and fuel being dumped into the cat which melted the catalyst. When this new problem arose, I had a third incident of 67 stored in the ECU (yeah, I was driving around with the CEL on).
Recent maintenance was done on July 02, 2010:
-5 quarts of Mobile 1 Tri-Synthetic oil
-Honda OEM filter
-Honda Aluminum Drain Plug Crush Washer
-Wearever Silver Brakes in the front
-Resurfaced Brembo OEM Blanks in the front
-Molykote77 on all brake component lubrication points
My Story
Before this started, I was driving with about 3 gallons of 87 octane (up to 10% ethanol content) and decided to fill it up. I used Shell gasoline from 11150 Lem Turner Road, Jacksonville, FL 32218. After about 15 miles of driving, this problem started. I pulled to a red light and without warning, the car simply cut off. I tried to restart the car, it would not start right away. I put on my Hazard Lights, and waived by the traffic behind; yeah, they honked at me. After many attempts, the car finally started; the light was red again. I resolved to mearly pull the car to the side of the road; I was at a four-way intersection. With the car idling fine, I put the car into D and it cut off immediately. I made several attempts to keep the car on while shifting to D, finally it worked when I held the RPMs just past 1000 while shifting into D. The car lunged forward and out of the roadway, but immediately cut off. I checked the dipstick for oil, there was some and it still looked new. I started it back up and sat in my car with it idling for about 10 minutes. I tried reving it a few times and found that it would stumble really bad at WOT, but was incrementally better with less application of throttle. I decided to try and limp it home. With the car idling steadily, I shifted to D with no application of throttle; the car didn't cut off. As soon as I touched the gas, the car shut off. I restared and tried the same trick, no gas, shifted to D, and let the idle speed accelarate the car forward. As soon as the RPMs got around 1100, I gave it a light tap on the gas and the car seemed fine, but I didn't want to push it so I never depressed the gas pedal beyond a slight touch. I drove about 10 miles and came to an intersection where I had to turn left and drive up a steep grade over a bridge. I had a red light and knew the car would not have enough road to build enough speed to get over the bridge after being stopped. While in D and stopped at that red light, the car shut off again. I ended up pushing it to a parking lot at that intersection and having it towed the rest of the way home.
Observations
1. When the motor stumbles, the dash lights do not flicker or fade. There does not seem to be any power failure in the Gauge Cluster or Small Lights Circuit.
2. While the car is idling, the Tachometer is steady. It does not blip, or fall, suddenly or unexpectedly.
3. When the car was moving, the Speedometer worked fine. It did not loose power or behave irradically.
4. I looked for smoke (of any color) to come out of my tailpipe, it never did. I have no strange emissions, just the same gassy smell I mentioned before.
5. With the key in the ignition, the Key-In Reminder chime works fine with the door open and giggling the key does not result in any power loss while idling.
Tests
1. I pulled the CEL codes and found: 67 and 70.
1a. Code 67 represents P0420: Catalyst System Efficiency Below Threashold
This is the same old code that has been sitting in there. I will get back to this at a later date, though I have a feeling that this was the first signs something bad was coming. I may fix this code by resolving my current issue.
1b. Code 70 represents P0715, P0720, P0725, P0730, P0740, P0753, and P0758: Automatic Transaxle
Helms sends me to Section 14 for the transmission, but has no suggested causes. I think the motor needs to be fixed first, then I can worry about the transmission. I plan on returning to this code later.
I cleared all the CEL codes stored the day this started. I have been working on this in my driveway, but even while reproducing the problem over and over, I have not had any more CEL codes stored since. Note: I have not driven the car anywhere, so the transmission has been out of the equation for now.
2. Fuel Pressure: I replaced the Banjo Bolt on the Fuel Filter with an adapter so that I could screw in a Fuel Pressure Gauge. Removing the Banjo Bolt relieves the pressure, so the adapter correctly read 0psi when installed.
2a. With the car idling and the Fuel Pressure Regulator vaccum hose connected, the pressure is 36.0psi. It should be between 31-38psi, so far so good.
2b. With the car idling and the Fuel Pressure Regulator vaccum hose disconnected, the pressure is 44.0psi. It should be between 40-47psi, so 44.0psi is good.
2c. With the car stumbling at WOT and the Fuel Pressure Regulator vaccum hose connected, the pressure creaps up to 37.5-38psi. When the car stalls out, the fuel pressure shoots up to 42psi. I guess this is cause with the motor stalled the vaccum supply dies out suddenly and lets the Fuel Pressure Regulator slam shut. So it seems the Fuel Pump is fine, but please let me know if I missed something.
3. Spark Plugs: I inspected all 6. All looked fine: correct gap, no liquid fuel, no oil, no excessive carbon (soot, black stuff), no excessive metal oxide deposits (white stuff), good center electrode insulator, center electrode still square, not rounded. I noticed that the electrode's arc point was clean and smooth, no pitting or corrosion. All plugs smelled fine though they did have a slight gassy smell. The since my maintenance schedule showed they would be due for a change next month and since I already had the replacements on hand; I went ahead replaced them; all gapped to 1.194mm.
4. Spark Plug Wires: I measured the resistance across all six. Resistance should be less than 25 kilo-Ohms. The plug wires measured (in kilo-Ohms): #1 17.3, #2 17.0, #3 14.0, #4 9.0, #5 8.0, #6 7.0; so the wires checked out fine.
5. Distributor Ignition Cap: no cracks, no damage, nor wear on the outside. Inside was clean aside from alittle sand that appears to have blown into it. My Distributor O-ring needs replacing, so I wiped the oil and dirt off the bottom of the outside of the cap and cleaned the points with 1000grit wet/dry automotive sandpaper.
6. Distributor Ignition Rotor: I inspected the Distributor Ignition Rotor Terminal, it looked fine, no fraying or obvious damage, pitting, or corrosion. With 1000grit wet/dry automotive sandpaper, I cleaned the spot where the cap's carbon point makes contact with the center of the rotor and wiped the distributor's internals clean.
7. Ignition Control Module: I measured the two volage inputs with the Key in ON. Yellow showed 8 volts, Green showed 8 volts. According to Helms, this means it checks out but please let me know if I missed something.
8. Ignition Coil: I measured the resistance across the two windings. I didn't worry about the tach output since I never observed any issue with the tach signal at the Gauge Cluster.
8a. Resistance across the Primary Winding was less than 0 Ohms; s/b 0.3-.04 Ohms, so far so good.
8b. Resistance across the Secondary Winding was 25 kilo-Ohms; s/b 14-22 kilo-Ohms, alittle off spec. When bought this BWD Ignition Coil back in June 2008 the Secondary Winding measured 12 kilo-Ohms, so 25 kilo-Ohms is odd and warrants further investigation.
8c. I swapped in a working OEM Ignition Coil (manufactured by TEC) that was pulled off a 1993 Honda Accord. Since the TEC Ignition Coil came from a 4-cylinder ignition system, the tach signal does not work with my tachometer. So it was no suprise that the Tachometer would not function while I was using the TEC. The TEC's Secondary Winding has 19 kilo-Ohms, Primary less than zero. The stumbling problem was not resolved by swapping ignition coils, so I put the BWD back in.
9. Top Dead Center (TDC) sensor: I measured resistance across the sensor. It should be 1.5-3.0 kilo-Ohms. I found 2.0 kilo-Ohms. According to Helms, this means it checks out but please let me know if I missed something.
10. Cylinder Position (CYP) sensor: I measured resistance across the sensor. It should be 1.5-3.0 kilo-Ohms. I found 2.9 kilo-Ohms. According to Helms, this means it checks out but please let me know if I missed something.
11. Air Filter: I inspected it. It was in "new" condition. I brushed off a June Bug and a leaf, and reinstalled the filter.
12. Throttle Position Sensor (TPS): with the Key in ON I measured voltage on the TPS.
12a. I found 4.2 volts on the TPS Reference Voltage (Yellow/Blue: VCC2).
12b. I found 0.2 volts at the TPS Output (Red/Black: TPS) while the throttle was in idle position.
12c. At WOT, I found 3.8 volts at the TPS Output (Red/Black: TPS).
13. Throttle Position Sensor (TPS): with the Key removed and with the car off I measured resistance across the TPS:
13a. Between the TPS Output (Red/Black: TPS) and TPS Ground (Green/Blue: SG2), I found 0.825 kilo-Ohms at idle; s/b 0.5-0.9 kilo-Ohms, so it looks like I'm good.
13b. Between the TPS Output (Red/Black: TPS) and TPS Reference Voltage (Yellow/Blue: VCC2), I found 1.8 kilo-Ohms at idle; s/b approx. 5 kilo-Ohms, I don't know if the TPS is bad. I guess most of the reference is getting back to the ECU at idle, but I thought the ECU stores the output in memory to measure the difference as throttle is applied. Perhaps someone can educate me on this.
14. Manifold Absolute Pressure (MAP) sensor: I measured voltage at the sensor in several conditions all while it was still connected to the ECU.
14a. With the Key in ON, I found 4.3 volts on the reference Yellow/White wire.
14b. With the key in ON, I found 2.3 volts on the output White/Yellow wire.
14c. With the motor idling at 500RPMs, I found 0.75 volts on the output wire.
14d. At WOT, I found the output jumps to about 2 volts but soon settles back down to 0.75
14e. After struggling to get the motor to 3000RPMs, I held it there for 60 seconds and then shut it off. I started it back up and I found high vacuum indicated for about a second. Afterwhich, the voltage dropped back to 0.75 volts as the motor idled at 500RPMs. This shows correct operation and rapid response.
15. Ignition Timing: I used a timing light to check out my timing. The Helms says I should find the Red mark 15 degrees (plus or minus 2 degrees) Below Top Dead Center (BTDC) with the motor idling at 750RPMs. As Helms instructs, I used the SCS Service Connector to connect the Green/Blue and Red terminals on the Service Check Connector (Blue 2-pin connector behind the glove box), and connected the timing light to the battery with the input on the #1 Spark Plug Ignition Wire. I found the red mark to be approx. 13 degrees Below Top Dead Center with the motor idling at 500RPMs, so my timing is good.
16. PGM-Fi Main Relay: I used a known working unit to replace the one in my car. There was no improvement in the stumbling accelaration.
17. Positive Crankcase Ventilation (PCV) Valve: I inspected it and found it to be in good working order: plunger not stuck, moves freely, o-ring solid and not cracked.
18. Intake Air Bypass (IAB): I observed the IAB Control Diaphram Valve allow the IAB to remain open with the car off and then close it with the car on. In WOT, the IAB Control Diaphram correctly opens the IAB at what I percieved to be the correct RPMs (4000), but could not confirm this since I am working by myself and have nobody to apply throttle and observe the tach while I observe the IAB Control Diaphram Valve. With the car off again, I disconnected the IAB Control Diaphram Valve Solenoid. There was no change in the issue at hand with the IAB open at all times.
19. Ignition Combination Switch: even though I had no indication that my Ignition Combination Switch had or was failing, I swapped in a known working unit from a 1990 Honda Accord EX. I plugged the brown connector at my fuse box and used a flat-head screw driver to start the car. This did not resolve my stumbling accelaration.
20. Fuel Treatment: I added 16 fluid ounces of Maximum 104+ Octane Boost to my fuel and rocked the car side to side to mix it in with the fuel in there already. This did not resolve my stumbling accelaration.
Things To Do
1. Bleed the Cooling System.
2. Check the Idle Air Control Valve.
3. Check the Crankshaft Position Sensor.
4. Check the ECU for damage on the board.
5. Check all sensor outputs for good connection to the ECU.
5. Check for good connection between the Brake Switch and ECU.
6. Remove the Catalytic Converter for visual inspection.
7. Find an easy way to test for contaminated fuel.
8. Test the Spark Plug Resistor.
Notes
1. I called the Shell station and asked if they have had any complaints about their fuel. The lady snapped at me that my insinuation was impossible since they sell nitrogen enriched fuel. I did not acknowledge her deflection and asked what their claims process is. She asked that I call back and speak with the manager. I asked what time he would be in, she said, "In the morning," and hung up on me.
2. I did a search on "rough accelaration stalling" and did not find any threads that described an issue exactly like mine.
Thank you all for reading and I welcome any comments or suggestions.
My car runs fine until the engine warms up; i.e. when the radiator fan comes on. Once warm, it idles steadily at 500RPMs but will intermittently stumble, maybe once or twice every 5 minutes, sometimes not at all. With the motor warm, if I try to rapidly go to Wide Open Throttle (WOT) the motor will stumble as the RPMs increase. Sometimes, the stumbling is really bad and the motor doesn't make it past 1000RPMs, it just stalls out. If the motor makes it past 1000RPMs, the stumbling continues and actually keeps the car from passing 3500RPMs; it just bounces between 3500RPMs and 3250RPMs. While in the 3250-3500RPM zone, if I let up on the throttle slightly, the stumbling disappears and the motor smoothly sails to redline without fail. Releasing the throttle slightly before the 3250-3500RPM zone does not prevent stumbling in the motor's approach to higher RPMs.
My Car
1997 Honda Accord EX-V6 sedan with the C27A4. The C27A4 uses mulit-point Programmed Fuel Injection (PGM-Fi) running On-Board Diagnostics standard 2 (OBD-II). I've got 226732 miles on the body and motor. All stock in the engine bay. I have a 4-speed automatic transmission. I stay on top of all maintenance, and perform all work myself.
Recent History
In the past year, the only unresolved Check Engine Light (CEL) I have gotten was 67: P0420 Catalyst System Efficiency Below Threashold. I've cleared it twice but have not gotten around to finding the cause. I have noticed in the last 3 months my exhaust has taken on a gassy smell which has progressively gotten stronger over those three months. It is as if the amount of unburnt fuel in my exhaust keeps increasing.
Florida doesn't have emissions testing and the catalytic converter was replaced in June 2009 with a Magnaflow OEM Replacement; I destroyed the original by leaving a ground wire loose which caused an intermittent power failure in the ECU which lead to backfiring and fuel being dumped into the cat which melted the catalyst. When this new problem arose, I had a third incident of 67 stored in the ECU (yeah, I was driving around with the CEL on).
Recent maintenance was done on July 02, 2010:
-5 quarts of Mobile 1 Tri-Synthetic oil
-Honda OEM filter
-Honda Aluminum Drain Plug Crush Washer
-Wearever Silver Brakes in the front
-Resurfaced Brembo OEM Blanks in the front
-Molykote77 on all brake component lubrication points
My Story
Before this started, I was driving with about 3 gallons of 87 octane (up to 10% ethanol content) and decided to fill it up. I used Shell gasoline from 11150 Lem Turner Road, Jacksonville, FL 32218. After about 15 miles of driving, this problem started. I pulled to a red light and without warning, the car simply cut off. I tried to restart the car, it would not start right away. I put on my Hazard Lights, and waived by the traffic behind; yeah, they honked at me. After many attempts, the car finally started; the light was red again. I resolved to mearly pull the car to the side of the road; I was at a four-way intersection. With the car idling fine, I put the car into D and it cut off immediately. I made several attempts to keep the car on while shifting to D, finally it worked when I held the RPMs just past 1000 while shifting into D. The car lunged forward and out of the roadway, but immediately cut off. I checked the dipstick for oil, there was some and it still looked new. I started it back up and sat in my car with it idling for about 10 minutes. I tried reving it a few times and found that it would stumble really bad at WOT, but was incrementally better with less application of throttle. I decided to try and limp it home. With the car idling steadily, I shifted to D with no application of throttle; the car didn't cut off. As soon as I touched the gas, the car shut off. I restared and tried the same trick, no gas, shifted to D, and let the idle speed accelarate the car forward. As soon as the RPMs got around 1100, I gave it a light tap on the gas and the car seemed fine, but I didn't want to push it so I never depressed the gas pedal beyond a slight touch. I drove about 10 miles and came to an intersection where I had to turn left and drive up a steep grade over a bridge. I had a red light and knew the car would not have enough road to build enough speed to get over the bridge after being stopped. While in D and stopped at that red light, the car shut off again. I ended up pushing it to a parking lot at that intersection and having it towed the rest of the way home.
Observations
1. When the motor stumbles, the dash lights do not flicker or fade. There does not seem to be any power failure in the Gauge Cluster or Small Lights Circuit.
2. While the car is idling, the Tachometer is steady. It does not blip, or fall, suddenly or unexpectedly.
3. When the car was moving, the Speedometer worked fine. It did not loose power or behave irradically.
4. I looked for smoke (of any color) to come out of my tailpipe, it never did. I have no strange emissions, just the same gassy smell I mentioned before.
5. With the key in the ignition, the Key-In Reminder chime works fine with the door open and giggling the key does not result in any power loss while idling.
Tests
1. I pulled the CEL codes and found: 67 and 70.
1a. Code 67 represents P0420: Catalyst System Efficiency Below Threashold
This is the same old code that has been sitting in there. I will get back to this at a later date, though I have a feeling that this was the first signs something bad was coming. I may fix this code by resolving my current issue.
1b. Code 70 represents P0715, P0720, P0725, P0730, P0740, P0753, and P0758: Automatic Transaxle
Helms sends me to Section 14 for the transmission, but has no suggested causes. I think the motor needs to be fixed first, then I can worry about the transmission. I plan on returning to this code later.
I cleared all the CEL codes stored the day this started. I have been working on this in my driveway, but even while reproducing the problem over and over, I have not had any more CEL codes stored since. Note: I have not driven the car anywhere, so the transmission has been out of the equation for now.
2. Fuel Pressure: I replaced the Banjo Bolt on the Fuel Filter with an adapter so that I could screw in a Fuel Pressure Gauge. Removing the Banjo Bolt relieves the pressure, so the adapter correctly read 0psi when installed.
2a. With the car idling and the Fuel Pressure Regulator vaccum hose connected, the pressure is 36.0psi. It should be between 31-38psi, so far so good.
2b. With the car idling and the Fuel Pressure Regulator vaccum hose disconnected, the pressure is 44.0psi. It should be between 40-47psi, so 44.0psi is good.
2c. With the car stumbling at WOT and the Fuel Pressure Regulator vaccum hose connected, the pressure creaps up to 37.5-38psi. When the car stalls out, the fuel pressure shoots up to 42psi. I guess this is cause with the motor stalled the vaccum supply dies out suddenly and lets the Fuel Pressure Regulator slam shut. So it seems the Fuel Pump is fine, but please let me know if I missed something.
3. Spark Plugs: I inspected all 6. All looked fine: correct gap, no liquid fuel, no oil, no excessive carbon (soot, black stuff), no excessive metal oxide deposits (white stuff), good center electrode insulator, center electrode still square, not rounded. I noticed that the electrode's arc point was clean and smooth, no pitting or corrosion. All plugs smelled fine though they did have a slight gassy smell. The since my maintenance schedule showed they would be due for a change next month and since I already had the replacements on hand; I went ahead replaced them; all gapped to 1.194mm.
4. Spark Plug Wires: I measured the resistance across all six. Resistance should be less than 25 kilo-Ohms. The plug wires measured (in kilo-Ohms): #1 17.3, #2 17.0, #3 14.0, #4 9.0, #5 8.0, #6 7.0; so the wires checked out fine.
5. Distributor Ignition Cap: no cracks, no damage, nor wear on the outside. Inside was clean aside from alittle sand that appears to have blown into it. My Distributor O-ring needs replacing, so I wiped the oil and dirt off the bottom of the outside of the cap and cleaned the points with 1000grit wet/dry automotive sandpaper.
6. Distributor Ignition Rotor: I inspected the Distributor Ignition Rotor Terminal, it looked fine, no fraying or obvious damage, pitting, or corrosion. With 1000grit wet/dry automotive sandpaper, I cleaned the spot where the cap's carbon point makes contact with the center of the rotor and wiped the distributor's internals clean.
7. Ignition Control Module: I measured the two volage inputs with the Key in ON. Yellow showed 8 volts, Green showed 8 volts. According to Helms, this means it checks out but please let me know if I missed something.
8. Ignition Coil: I measured the resistance across the two windings. I didn't worry about the tach output since I never observed any issue with the tach signal at the Gauge Cluster.
8a. Resistance across the Primary Winding was less than 0 Ohms; s/b 0.3-.04 Ohms, so far so good.
8b. Resistance across the Secondary Winding was 25 kilo-Ohms; s/b 14-22 kilo-Ohms, alittle off spec. When bought this BWD Ignition Coil back in June 2008 the Secondary Winding measured 12 kilo-Ohms, so 25 kilo-Ohms is odd and warrants further investigation.
8c. I swapped in a working OEM Ignition Coil (manufactured by TEC) that was pulled off a 1993 Honda Accord. Since the TEC Ignition Coil came from a 4-cylinder ignition system, the tach signal does not work with my tachometer. So it was no suprise that the Tachometer would not function while I was using the TEC. The TEC's Secondary Winding has 19 kilo-Ohms, Primary less than zero. The stumbling problem was not resolved by swapping ignition coils, so I put the BWD back in.
9. Top Dead Center (TDC) sensor: I measured resistance across the sensor. It should be 1.5-3.0 kilo-Ohms. I found 2.0 kilo-Ohms. According to Helms, this means it checks out but please let me know if I missed something.
10. Cylinder Position (CYP) sensor: I measured resistance across the sensor. It should be 1.5-3.0 kilo-Ohms. I found 2.9 kilo-Ohms. According to Helms, this means it checks out but please let me know if I missed something.
11. Air Filter: I inspected it. It was in "new" condition. I brushed off a June Bug and a leaf, and reinstalled the filter.
12. Throttle Position Sensor (TPS): with the Key in ON I measured voltage on the TPS.
12a. I found 4.2 volts on the TPS Reference Voltage (Yellow/Blue: VCC2).
12b. I found 0.2 volts at the TPS Output (Red/Black: TPS) while the throttle was in idle position.
12c. At WOT, I found 3.8 volts at the TPS Output (Red/Black: TPS).
13. Throttle Position Sensor (TPS): with the Key removed and with the car off I measured resistance across the TPS:
13a. Between the TPS Output (Red/Black: TPS) and TPS Ground (Green/Blue: SG2), I found 0.825 kilo-Ohms at idle; s/b 0.5-0.9 kilo-Ohms, so it looks like I'm good.
13b. Between the TPS Output (Red/Black: TPS) and TPS Reference Voltage (Yellow/Blue: VCC2), I found 1.8 kilo-Ohms at idle; s/b approx. 5 kilo-Ohms, I don't know if the TPS is bad. I guess most of the reference is getting back to the ECU at idle, but I thought the ECU stores the output in memory to measure the difference as throttle is applied. Perhaps someone can educate me on this.
14. Manifold Absolute Pressure (MAP) sensor: I measured voltage at the sensor in several conditions all while it was still connected to the ECU.
14a. With the Key in ON, I found 4.3 volts on the reference Yellow/White wire.
14b. With the key in ON, I found 2.3 volts on the output White/Yellow wire.
14c. With the motor idling at 500RPMs, I found 0.75 volts on the output wire.
14d. At WOT, I found the output jumps to about 2 volts but soon settles back down to 0.75
14e. After struggling to get the motor to 3000RPMs, I held it there for 60 seconds and then shut it off. I started it back up and I found high vacuum indicated for about a second. Afterwhich, the voltage dropped back to 0.75 volts as the motor idled at 500RPMs. This shows correct operation and rapid response.
15. Ignition Timing: I used a timing light to check out my timing. The Helms says I should find the Red mark 15 degrees (plus or minus 2 degrees) Below Top Dead Center (BTDC) with the motor idling at 750RPMs. As Helms instructs, I used the SCS Service Connector to connect the Green/Blue and Red terminals on the Service Check Connector (Blue 2-pin connector behind the glove box), and connected the timing light to the battery with the input on the #1 Spark Plug Ignition Wire. I found the red mark to be approx. 13 degrees Below Top Dead Center with the motor idling at 500RPMs, so my timing is good.
16. PGM-Fi Main Relay: I used a known working unit to replace the one in my car. There was no improvement in the stumbling accelaration.
17. Positive Crankcase Ventilation (PCV) Valve: I inspected it and found it to be in good working order: plunger not stuck, moves freely, o-ring solid and not cracked.
18. Intake Air Bypass (IAB): I observed the IAB Control Diaphram Valve allow the IAB to remain open with the car off and then close it with the car on. In WOT, the IAB Control Diaphram correctly opens the IAB at what I percieved to be the correct RPMs (4000), but could not confirm this since I am working by myself and have nobody to apply throttle and observe the tach while I observe the IAB Control Diaphram Valve. With the car off again, I disconnected the IAB Control Diaphram Valve Solenoid. There was no change in the issue at hand with the IAB open at all times.
19. Ignition Combination Switch: even though I had no indication that my Ignition Combination Switch had or was failing, I swapped in a known working unit from a 1990 Honda Accord EX. I plugged the brown connector at my fuse box and used a flat-head screw driver to start the car. This did not resolve my stumbling accelaration.
20. Fuel Treatment: I added 16 fluid ounces of Maximum 104+ Octane Boost to my fuel and rocked the car side to side to mix it in with the fuel in there already. This did not resolve my stumbling accelaration.
Things To Do
1. Bleed the Cooling System.
2. Check the Idle Air Control Valve.
3. Check the Crankshaft Position Sensor.
4. Check the ECU for damage on the board.
5. Check all sensor outputs for good connection to the ECU.
5. Check for good connection between the Brake Switch and ECU.
6. Remove the Catalytic Converter for visual inspection.
7. Find an easy way to test for contaminated fuel.
8. Test the Spark Plug Resistor.
Notes
1. I called the Shell station and asked if they have had any complaints about their fuel. The lady snapped at me that my insinuation was impossible since they sell nitrogen enriched fuel. I did not acknowledge her deflection and asked what their claims process is. She asked that I call back and speak with the manager. I asked what time he would be in, she said, "In the morning," and hung up on me.
2. I did a search on "rough accelaration stalling" and did not find any threads that described an issue exactly like mine.
Thank you all for reading and I welcome any comments or suggestions.
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