Running rich, rough idle
Thread Starter
Joined: Nov 2006
Posts: 4,961
Likes: 1
From: SF Bay Area, CA
Running rich, rough idle
MY2002
79,XXX miles
Observations:
On my way home one night, I noticed the car was no longer smooth under acceleration. It almost felt like the car was pulsing or surging. After pulling into the garage, I noticed the car had a rough idle. Almost like a pulsing every once in a while. Let the car cool down overnight and started it up again in the morning. Idle seemed significantly worse. There was also a distinct smell of gas. The car had trouble maintaining a smooth idle. It would be okay one second, and would either rise or drop. Pulses and muted pops would be associated with these fluctuations.
Visually, I can see small puffs of dark smoke associated with each muted pop from the tail pipe.
Pulling the spark plugs showed that they were covered in dry black soot. Not oily or damp.
What I've Tried:
- Replaced old plugs with new NGK IFR7G-11KS Laser Iridium (Iridium version of OEM NGK plug)
- Tested with known good set of CoilPacks
- "Map Whack" fix, also pulled in connection with zip-tie TSB (https://www.s2ki.com/s2000/topic/253...-sensor-whack/)
Presently:
So far the issue is exists. Next step, I'll probably try cleaning the IAC (https://www.s2ki.com/s2000/topic/492...ean-iac-valve/), but I don't know that it will help my issues with running rich. Is it likely that my primary 02 sensor ( the one located on the header) has gone bad? Would my symptoms be consistent with one that has gone bad?
For future reference, DENSO replacements for the O2 sensors (OE replacement) are as follows for an AP1 / MY2002:
Primary / Upstream : 234-4124
Secondary / Downstream: 234-4601
Alternatively, I've heard very positive things from this site (link is for AP1): http://oxygensensors.com/catalog.php?&pkey=1430228
79,XXX miles
Observations:
On my way home one night, I noticed the car was no longer smooth under acceleration. It almost felt like the car was pulsing or surging. After pulling into the garage, I noticed the car had a rough idle. Almost like a pulsing every once in a while. Let the car cool down overnight and started it up again in the morning. Idle seemed significantly worse. There was also a distinct smell of gas. The car had trouble maintaining a smooth idle. It would be okay one second, and would either rise or drop. Pulses and muted pops would be associated with these fluctuations.
Visually, I can see small puffs of dark smoke associated with each muted pop from the tail pipe.
Pulling the spark plugs showed that they were covered in dry black soot. Not oily or damp.
What I've Tried:
- Replaced old plugs with new NGK IFR7G-11KS Laser Iridium (Iridium version of OEM NGK plug)
- Tested with known good set of CoilPacks
- "Map Whack" fix, also pulled in connection with zip-tie TSB (https://www.s2ki.com/s2000/topic/253...-sensor-whack/)
Presently:
So far the issue is exists. Next step, I'll probably try cleaning the IAC (https://www.s2ki.com/s2000/topic/492...ean-iac-valve/), but I don't know that it will help my issues with running rich. Is it likely that my primary 02 sensor ( the one located on the header) has gone bad? Would my symptoms be consistent with one that has gone bad?
For future reference, DENSO replacements for the O2 sensors (OE replacement) are as follows for an AP1 / MY2002:
Primary / Upstream : 234-4124
Secondary / Downstream: 234-4601
Alternatively, I've heard very positive things from this site (link is for AP1): http://oxygensensors.com/catalog.php?&pkey=1430228
Registered User
Joined: Jan 2013
Posts: 263
Likes: 1
From: Manteca, CA
AP1? Have you done VA yet? Air filter clean? You might want to try and check the IAC and throttle body, free to do and could cause the rough idle. After doing that try and reset the ecu and do idle re-learn. Make sure the little hole in the throttle body where the MAP sensor goes is not plugged (or whacking the crap out of it pretty much does nothing). Mine was caked with black scaly garbage which was blocking passage to the MAP. Good luck!!!!
Registered User
Joined: Jan 2013
Posts: 263
Likes: 1
From: Manteca, CA
AP1? Have you done VA yet? Air filter clean? You might want to try and check the IAC and throttle body, free to do and could cause the rough idle. After doing that try and reset the ecu and do idle re-learn. Make sure the little hole in the throttle body where the MAP sensor goes is not plugged (or whacking the crap out of it pretty much does nothing). Mine was caked with black scaly garbage which was blocking passage to the MAP. Good luck!!!!
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Thread Starter
Joined: Nov 2006
Posts: 4,961
Likes: 1
From: SF Bay Area, CA
Thanks for the reply guys. Update:
- Throttle body is clean
- Air Filter is clean
- Valve adjustment was done 15k miles ago
- IAC is clean
- Map sensor hole in throttle body is clean
- Swapped known good map sensor, problem is still present
Summitrider: I'll try to grab a tool and see if I can read the voltage, but seeing that I swapped with a good MAP sensor, I would say its not the issue.
More observations:
Car has erratic idle. Initially Idles high with muted pops. Eventually idles at 900-1000 steadily, then becomes erratic, going back and forth between 1k and 1.5k.
If I blip the throttle, the idle comes down far too low, sometimes almost causing the car to stall.
- Throttle body is clean
- Air Filter is clean
- Valve adjustment was done 15k miles ago
- IAC is clean
- Map sensor hole in throttle body is clean
- Swapped known good map sensor, problem is still present
Summitrider: I'll try to grab a tool and see if I can read the voltage, but seeing that I swapped with a good MAP sensor, I would say its not the issue.
More observations:
Car has erratic idle. Initially Idles high with muted pops. Eventually idles at 900-1000 steadily, then becomes erratic, going back and forth between 1k and 1.5k.
If I blip the throttle, the idle comes down far too low, sometimes almost causing the car to stall.
Thread Starter
Joined: Nov 2006
Posts: 4,961
Likes: 1
From: SF Bay Area, CA
UPDATE
Dropped in a new Primary/Lambda O2 sensor last night. The old plug looked very much like the spark plugs: covered in dry dark soot.
Disconnected the battery and the "backup" fuse in the driver kick panel for a full ECU reset. Let the car sit for 5 minutes with battery disconnected and fuse pulled. After connecting everything back up and starting the car, my heart sank as the rough idle, erratic revs, and muted pops continued like before. I let the car sit idling for 5 minutes hoping the ECU would learn the new settings. After 5 minutes, the problem appeared to persist so I shut off the car. The car sat for another 2-3 minutes before I attempted to restart again. Same issue. If I blipped the throttle, there was a definite delay in throttle response. Then the revs would drop so low that the car would come close to stalling (sounded almost like a lawn mower as it got near that point).
Again, shut off the car, took a look around the engine bay for vacuum leaks. None.
One more time: restarted the engine and BAM! --Normal--. Idle was smooth, no erratic revs, no smell of fuel. My ECU must be a slow learner. Took the car on a drive, went through the rev range in most gears. Everything seems okay for now. Also let the car sit overnight and restarted it cold. Everything seems normal. I'll update after driving the car for a few days, but hopefully this well help anyone that has this issue down the line.
Dropped in a new Primary/Lambda O2 sensor last night. The old plug looked very much like the spark plugs: covered in dry dark soot.
Disconnected the battery and the "backup" fuse in the driver kick panel for a full ECU reset. Let the car sit for 5 minutes with battery disconnected and fuse pulled. After connecting everything back up and starting the car, my heart sank as the rough idle, erratic revs, and muted pops continued like before. I let the car sit idling for 5 minutes hoping the ECU would learn the new settings. After 5 minutes, the problem appeared to persist so I shut off the car. The car sat for another 2-3 minutes before I attempted to restart again. Same issue. If I blipped the throttle, there was a definite delay in throttle response. Then the revs would drop so low that the car would come close to stalling (sounded almost like a lawn mower as it got near that point).
Again, shut off the car, took a look around the engine bay for vacuum leaks. None.
One more time: restarted the engine and BAM! --Normal--. Idle was smooth, no erratic revs, no smell of fuel. My ECU must be a slow learner. Took the car on a drive, went through the rev range in most gears. Everything seems okay for now. Also let the car sit overnight and restarted it cold. Everything seems normal. I'll update after driving the car for a few days, but hopefully this well help anyone that has this issue down the line.
