Misfiring problem
03-06-2003, 10:25 AM
#1
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Join Date: Feb 2003
Posts: 5
Misfiring problem
1996 acocrd EX..
My car is throwing codes 71, and 72. Those are the codes for misfire detected in cylinders 1 and 2. It is definatly noticable while maintaining a constant speed, with RPMs below 3K. It doesnt happen when I am accelerating, and it doesnt happen when I am above 3K RPM. I thought it could be the IACV, but it seems to be working fine.
The CEL always comes on between 2K and 3k rpms, and ususally takes about 25 minutes to come on after reseting the ECU. I tried gapping the plugs a little smaller, but I dont think it made any difference (.035).
Ignition includes:
MSD sport compact ignition controller
MSD BTM
MSD dist. cap
MSD external coil
MSD 8.5 plug wires
new rotor
2 step colder plugs
fuel management right now is only a 12:1 vortec FMU.. Could it be a fuel problem, maybe the stock fuel reg? I wouldnt think so since it never happens while in boost.
If anyone has any suggestions, please let me know
Thanks
Garrett
My car is throwing codes 71, and 72. Those are the codes for misfire detected in cylinders 1 and 2. It is definatly noticable while maintaining a constant speed, with RPMs below 3K. It doesnt happen when I am accelerating, and it doesnt happen when I am above 3K RPM. I thought it could be the IACV, but it seems to be working fine.
The CEL always comes on between 2K and 3k rpms, and ususally takes about 25 minutes to come on after reseting the ECU. I tried gapping the plugs a little smaller, but I dont think it made any difference (.035).
Ignition includes:
MSD sport compact ignition controller
MSD BTM
MSD dist. cap
MSD external coil
MSD 8.5 plug wires
new rotor
2 step colder plugs
fuel management right now is only a 12:1 vortec FMU.. Could it be a fuel problem, maybe the stock fuel reg? I wouldnt think so since it never happens while in boost.
If anyone has any suggestions, please let me know
Thanks
Garrett
03-06-2003, 01:39 PM
#3
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Join Date: Feb 2003
Posts: 5
Re:Misfiring problem
The distributor on my car is not adjustable, so there is no way to adjust timing, but no, I havnt checked it. Could it be off, even if there is no way to adjust timing?
I guess the car could be running rich, because it does seem to go through gas a little quicker, even when i dont get on it much. I just dont see how it would run any richer without any fuel mods, besides an FMU, especially when my problem occurs before I go into boost.
I guess the car could be running rich, because it does seem to go through gas a little quicker, even when i dont get on it much. I just dont see how it would run any richer without any fuel mods, besides an FMU, especially when my problem occurs before I go into boost.
03-06-2003, 05:50 PM
#4
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Join Date: Dec 2002
Posts: 13,991
Re:Misfiring problem
Check your basics...
Compression
Fuel
Spark
Timing
Since you have been running a FMU its possible that the seals in your injectors are just shot, and adding way to much fuel. Try another set of injectors to see if it changes.
Compression, just do a quick test to make sure everything is ok.. Its best to rule this out, so you know you dont have any internal problems.
Spark, Make sure your full ignition system is all up to Par, no corrioson, plugs in good shape, along with good wires. (incl cap and rotor) Lots of stuff can cause misfires.
Timing, Ignition timing wouldnt really cause a miss, but I would still make sure its ok. Cam timing can jump and make a car run like ----, but its very unlikly,
Good luck,
Jeff
Compression
Fuel
Spark
Timing
Since you have been running a FMU its possible that the seals in your injectors are just shot, and adding way to much fuel. Try another set of injectors to see if it changes.
Compression, just do a quick test to make sure everything is ok.. Its best to rule this out, so you know you dont have any internal problems.
Spark, Make sure your full ignition system is all up to Par, no corrioson, plugs in good shape, along with good wires. (incl cap and rotor) Lots of stuff can cause misfires.
Timing, Ignition timing wouldnt really cause a miss, but I would still make sure its ok. Cam timing can jump and make a car run like ----, but its very unlikly,
Good luck,
Jeff
03-06-2003, 06:46 PM
#6
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Thread Starter
Join Date: Feb 2003
Posts: 5
Re:Misfiring problem
Since you have been running a FMU its possible that the seals in your injectors are just shot, and adding way to much fuel. Try another set of injectors to see if it changes.
as far as compression, I will check that too, but I really doubt thats the problem. like you said though, its better to rule that out.
thanks
03-07-2003, 01:08 PM
#7
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Join Date: Feb 2003
Posts: 5
Re:Misfiring problem
alright.. checked out the compression, and every cylinder is 180 except cylinder 1, which is 160..
every plug shows signs of running rich.. Now I really dont know what to do. There isnt any oil signs on the plugs, so I dont think its the rings.. Maybe a valve?
every plug shows signs of running rich.. Now I really dont know what to do. There isnt any oil signs on the plugs, so I dont think its the rings.. Maybe a valve?
03-08-2003, 06:05 PM
#8
Administrator
Join Date: Dec 2002
Posts: 13,991
Re:Misfiring problem
Possible a valve, if you are showing signs of running rich, it could be the injectors, try swapping out with another set.
If you think its a valve, you would need to do a cylinder leak down test.
The compression test seems just fine.
Jeff
If you think its a valve, you would need to do a cylinder leak down test.
The compression test seems just fine.
Jeff
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