Another rough idle / misfire case
06-05-2007, 03:35 PM
#11
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Originally Posted by negcamber,Jun 4 2007, 10:08 AM
Had the same symptoms...replacing the injectors did the trick.
There is a long thread about the misfire codes and various solutions...just about always solved by new injectors (not used or just cleaned...that just delays replacing the injectors)
There is a long thread about the misfire codes and various solutions...just about always solved by new injectors (not used or just cleaned...that just delays replacing the injectors)
Same symptoms 2 years ago for me...
06-09-2007, 11:10 AM
#12
I've had time to perform some of the tests and checks mentioned above. Adding to my original list, I have now tried the following:
Checked Coil Packs
I removed the coil pack connectors, one at a time, per the advice of Honda_mann. Each time the engine idle became notably worse. This seems to indicate they're working, short of a more direct test (coil resistance measurement, etc?). I've not seen any other information on how to more directly check them, so at this point I'm going to assume they're ok, with a grain of salt.
Ignition Timing
I managed to find out how to put the ECU into "SCS" mode. This is the mode that the ECU is in when the OBD connector is shorted to get the CEL blink codes. It holds the timing steady so it's not bouncing around while trying to measure it. There is a red mark on the crank pully at 5 degrees BTDC, and two black marks on either side of the red one, indicating +/-2 degrees. This is also the specification from the shop manual (go figure
). My timing was just a hair off of the 5 degree (red) mark, and well within tolerance.
Throttle Body Cleaning
This was fairly simple. I removed the throttle body and sprayed it out with carb cleaner. I payed particular attention to the MAP sensor port. It wasn't too dirty to begin with, so I doubted this would have an effect. No harm in cleaning it out, though. While I was at it, I cleaned out the intake manifold a bit as well. It, too, was not very dirty.
Idle Air Control (IAC) Valve Check
The shop manual lists this check as a troubleshooting step for a low idle. The test is as simple as unplugging the IAC connector at idle and noting what the idle speed does. In this case, the idle climbed to about 1500 RPM. Per the shop manual, the IAC should be good, though a more thorough idle speed test should be performed when my scan tool arrives.
Idle Air Control (IAC) Valve Cleaning
Per suggestions in other threads, I removed the IAC and cleaned it out with carb cleaner. Like the throttle body and intake manifold, it was not very dirty. Note to other newbies doing this: The rubber hoses connected to this are not vacuum hoses. They are coolant hoses. Watch out.
The Results
At the end of the day, I reset the ECU by pulling the back-up fuse. I let the car warm up and idle for a while, then took it for a drive so the ECU could re-learn. The idle is still low and I can hear the puffing from the exhaust indicative of misfiring. There is no CEL yet, as I've only driven the car once. The scan tool will be valuable when it arrives. It's really starting to look like it's going to be the injectors, as others have found. Everything else seems to be in pretty good shape.
Stay tuned...
Checked Coil Packs
I removed the coil pack connectors, one at a time, per the advice of Honda_mann. Each time the engine idle became notably worse. This seems to indicate they're working, short of a more direct test (coil resistance measurement, etc?). I've not seen any other information on how to more directly check them, so at this point I'm going to assume they're ok, with a grain of salt.
Ignition Timing
I managed to find out how to put the ECU into "SCS" mode. This is the mode that the ECU is in when the OBD connector is shorted to get the CEL blink codes. It holds the timing steady so it's not bouncing around while trying to measure it. There is a red mark on the crank pully at 5 degrees BTDC, and two black marks on either side of the red one, indicating +/-2 degrees. This is also the specification from the shop manual (go figure
). My timing was just a hair off of the 5 degree (red) mark, and well within tolerance.Throttle Body Cleaning
This was fairly simple. I removed the throttle body and sprayed it out with carb cleaner. I payed particular attention to the MAP sensor port. It wasn't too dirty to begin with, so I doubted this would have an effect. No harm in cleaning it out, though. While I was at it, I cleaned out the intake manifold a bit as well. It, too, was not very dirty.
Idle Air Control (IAC) Valve Check
The shop manual lists this check as a troubleshooting step for a low idle. The test is as simple as unplugging the IAC connector at idle and noting what the idle speed does. In this case, the idle climbed to about 1500 RPM. Per the shop manual, the IAC should be good, though a more thorough idle speed test should be performed when my scan tool arrives.
Idle Air Control (IAC) Valve Cleaning
Per suggestions in other threads, I removed the IAC and cleaned it out with carb cleaner. Like the throttle body and intake manifold, it was not very dirty. Note to other newbies doing this: The rubber hoses connected to this are not vacuum hoses. They are coolant hoses. Watch out.
The Results
At the end of the day, I reset the ECU by pulling the back-up fuse. I let the car warm up and idle for a while, then took it for a drive so the ECU could re-learn. The idle is still low and I can hear the puffing from the exhaust indicative of misfiring. There is no CEL yet, as I've only driven the car once. The scan tool will be valuable when it arrives. It's really starting to look like it's going to be the injectors, as others have found. Everything else seems to be in pretty good shape.
Stay tuned...
06-11-2007, 06:25 AM
#13
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ive seen the similar issues too...
did you do an actual leakdown test, as it is different from compression. my compression showed amazing like yours, but when you do leakdown...you should have under 10% (under 5% ideally) in each cylinder.
for instance, ive seen 0-2% leakage thru cyl (valves) 1,2,4...but cyl 3 showed 30% (to high!). i think the reason was exh. valve number 3 wasn't closing fully (due to maybe carbon build up? or who knows for whatever reason...not seating right anymore maybe? i dunno). anyways, then you would wanna do the valve, guides, seats, etc. for intake/exh on that cyl, unless you just get the whole head done....car shold be good again
tho then ive seen cars with the CEL pop back on again after 500km of 're-breakin' driving (keeping it under 5/6K rpm, up to 1000km to be safe) after being freshened up...odd eh? maybe it also is down to one of the more 'basic' things you listed above. i will have a tech look into it for me....
did you do an actual leakdown test, as it is different from compression. my compression showed amazing like yours, but when you do leakdown...you should have under 10% (under 5% ideally) in each cylinder.
for instance, ive seen 0-2% leakage thru cyl (valves) 1,2,4...but cyl 3 showed 30% (to high!). i think the reason was exh. valve number 3 wasn't closing fully (due to maybe carbon build up? or who knows for whatever reason...not seating right anymore maybe? i dunno). anyways, then you would wanna do the valve, guides, seats, etc. for intake/exh on that cyl, unless you just get the whole head done....car shold be good again
tho then ive seen cars with the CEL pop back on again after 500km of 're-breakin' driving (keeping it under 5/6K rpm, up to 1000km to be safe) after being freshened up...odd eh? maybe it also is down to one of the more 'basic' things you listed above. i will have a tech look into it for me....
06-15-2007, 06:00 PM
#14
Update
Well, it's been 6 days since I performed the last tests (from my post above). No CEL yet. This is a good sign. The last time the CEL came on, it did so within a day or two of being turned off. The car seemed to idle a bit better all week.
Idle Check
My scan tool arrived, so I was able to check the idle. It's right at 800rpm with no load and 900rpm with the air condiioning on, just like it should be. It still seems a bit rough, though it could be my imagination.
IAC?
The only thing that really changed last weekend was the IAC. I cleaned it, along with the (already clean) throttle body. I suppose this could have been the issue, but I'm curious as to why I was getting misfire codes on all cylinders.
Valves?
The ECU seems to be doing it's job with idle and timing, but the idle still seems a bit lumpy. It's possible that I adjusted the valves a bit too tight. I may take another look at them this weekend.
Fuel?
It was also suggested that I may have been getting bad fuel. I have been using Shell V-Power forever, with the occasional BP Ultimate, so bad fuel is not likely. I've heard of "summer" versus "winter" blends of fuel, and I suppose this may be a possibility. I'm only including it here for future reference.
In a nutshell...
It would appear that this case is closed, at least for the time being. If the symptoms come back or there is any new information, I'll add it to this thread for future reference. Otherwise, anyone reading this can assume the problem is gone.
Thanks to those who offered insight and suggestions.
Well, it's been 6 days since I performed the last tests (from my post above). No CEL yet. This is a good sign. The last time the CEL came on, it did so within a day or two of being turned off. The car seemed to idle a bit better all week.
Idle Check
My scan tool arrived, so I was able to check the idle. It's right at 800rpm with no load and 900rpm with the air condiioning on, just like it should be. It still seems a bit rough, though it could be my imagination.
IAC?
The only thing that really changed last weekend was the IAC. I cleaned it, along with the (already clean) throttle body. I suppose this could have been the issue, but I'm curious as to why I was getting misfire codes on all cylinders.
Valves?
The ECU seems to be doing it's job with idle and timing, but the idle still seems a bit lumpy. It's possible that I adjusted the valves a bit too tight. I may take another look at them this weekend.
Fuel?
It was also suggested that I may have been getting bad fuel. I have been using Shell V-Power forever, with the occasional BP Ultimate, so bad fuel is not likely. I've heard of "summer" versus "winter" blends of fuel, and I suppose this may be a possibility. I'm only including it here for future reference.
In a nutshell...
It would appear that this case is closed, at least for the time being. If the symptoms come back or there is any new information, I'll add it to this thread for future reference. Otherwise, anyone reading this can assume the problem is gone.
Thanks to those who offered insight and suggestions.
06-21-2007, 10:34 PM
#15
I did the post that was referred to at the beginning of this thread (Random1)
https://www.s2ki.com/forums/index.ph...ic=292304&st=0
If you go to the end, I just posted that new injectors were put in and it runs perfectly now. How the injectors get funked up is still a mystery. So, root cause is still not known!
This type of misfire, the puffing out exhaust, is a lean misfire cause by not enough or no fuel getting in for the ignition. So, a "puff" comes out. It appears to be very benign. You really have to hear and feel it to know what it is.
In my case it go so bad it was embarrassing and it was happening at higher RPM with no load. The CEL light was on constantly and it had codes for all cylinders again.
It appears that quite a few of these are showing up and these are only the ones being posted here. I wonder what the dealers/shops see?
https://www.s2ki.com/forums/index.ph...ic=292304&st=0
If you go to the end, I just posted that new injectors were put in and it runs perfectly now. How the injectors get funked up is still a mystery. So, root cause is still not known!
This type of misfire, the puffing out exhaust, is a lean misfire cause by not enough or no fuel getting in for the ignition. So, a "puff" comes out. It appears to be very benign. You really have to hear and feel it to know what it is.
In my case it go so bad it was embarrassing and it was happening at higher RPM with no load. The CEL light was on constantly and it had codes for all cylinders again.
It appears that quite a few of these are showing up and these are only the ones being posted here. I wonder what the dealers/shops see?
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