Looking for some guidance - random misfire
12-13-2007, 07:59 PM
#1
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Thread Starter
Looking for some guidance - random misfire
Getting P0300, 301, etc... codes (with the flashing CEL) in boost between 4500 and 6000 rpm in 3rd and 4th gear. Cruise a bit and the flashing CEL goes away, restart the car a second time and then flashing CEL will lock solid.
Does not happen at all in 1st or 2nd gear. Does not happen below 1 or 2 psi in any gear all the way to redline.
Idle is a little rough following flashing CEL event - reset the ECU and it idles fine but with a little occasional popping from the exhaust. Watching the wideband when this happens I see the AF going rich to slightly lean (10.4 to 13) and there is obvous chugging in the acceleration.
Pulled the plugs (BRK8EIX) and they all look the same - slightly rich. Replaced them with new and the problem is still there. Did a compression check and all cylinders are reading the same - my car has alway read low 180-185 on all cylinders.
So - I am thinking it is one of two things and eliminating injectors and coils since it is all cylinders and unlikely that all 4 would fail at the same time:
Fuel pressure is low - will test it out this weekend )possible FPR or fuel pump issue).
or
Valves are to tight - valves were adjusted about a month ago and the car was running fine up until today. Guess I will do that this weekend also.
Looking for what others may think could be the culprit. Can valves actually tighten up over time?
Thanks in advance
Does not happen at all in 1st or 2nd gear. Does not happen below 1 or 2 psi in any gear all the way to redline.
Idle is a little rough following flashing CEL event - reset the ECU and it idles fine but with a little occasional popping from the exhaust. Watching the wideband when this happens I see the AF going rich to slightly lean (10.4 to 13) and there is obvous chugging in the acceleration.
Pulled the plugs (BRK8EIX) and they all look the same - slightly rich. Replaced them with new and the problem is still there. Did a compression check and all cylinders are reading the same - my car has alway read low 180-185 on all cylinders.
So - I am thinking it is one of two things and eliminating injectors and coils since it is all cylinders and unlikely that all 4 would fail at the same time:
Fuel pressure is low - will test it out this weekend )possible FPR or fuel pump issue).
or
Valves are to tight - valves were adjusted about a month ago and the car was running fine up until today. Guess I will do that this weekend also.
Looking for what others may think could be the culprit. Can valves actually tighten up over time?
Thanks in advance
12-13-2007, 09:04 PM
#3
Former Moderator
Thread Starter
SC - Ultimate
Pull the belt off the SC and tie open the by-pass on the SC and I can not get it to throw a CEL. Of course it does not see boost like that.
Pull the belt off the SC and tie open the by-pass on the SC and I can not get it to throw a CEL. Of course it does not see boost like that.
12-14-2007, 09:53 AM
#4
Former Moderator
Thread Starter
No other thoughts?
Added note - It seemed like it would not happen if I boosted with 2 bars on the temp gauge (AP1) or just after it rolled to the third bar. Only seems to happen after it has been on 3 bars for a while - hinting back at perhaps the valve lash being a little to thin.
Added note - It seemed like it would not happen if I boosted with 2 bars on the temp gauge (AP1) or just after it rolled to the third bar. Only seems to happen after it has been on 3 bars for a while - hinting back at perhaps the valve lash being a little to thin.
12-15-2007, 11:45 AM
#5
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Thread Starter
Not the valve adjustment - they were a little on the tight side but a readjustement did not correct the problem.
Now I gotta find a way to check the fuel pressure.
Now I gotta find a way to check the fuel pressure.
12-15-2007, 12:32 PM
#6
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Do you have any other noises associated with this?
Your symptoms sound like a bearing on the way out.
A leak-down test will tell you if you have a bad ring or a bent valve.
Your symptoms sound like a bearing on the way out.
A leak-down test will tell you if you have a bad ring or a bent valve.
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12-16-2007, 01:07 PM
#8
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Thread Starter
Originally Posted by Asura,Dec 15 2007, 01:32 PM
Do you have any other noises associated with this?
Your symptoms sound like a bearing on the way out.
A leak-down test will tell you if you have a bad ring or a bent valve.
Your symptoms sound like a bearing on the way out.
A leak-down test will tell you if you have a bad ring or a bent valve.
12-16-2007, 01:24 PM
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Originally Posted by WLAURENT,Dec 13 2007, 09:59 PM
Watching the wideband when this happens I see the AF going rich to slightly lean (10.4 to 13) and there is obvous chugging in the acceleration.
12-16-2007, 01:42 PM
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try cleaning the map sensor, tps sensor, IAT sensor. just had acar with same problem, after new plugs, exhanged all coils, and looked over the tune, nothing changed
pulled and cleaned like said above - no more misfire, idles smoth again,
give that a try
pulled and cleaned like said above - no more misfire, idles smoth again,
give that a try