How to tell if a cylinder is not firing or misfiring?
#41
if you have a scanner that will show it, look at the knock count and see what it is. if your sensor is picking up a false knock it will reatard the timing and you will feel a pretty good loss of power. so look at timing advance too.
#42
Join Date: Nov 2007
Location: Eastern PA,
Posts: 10,387
Back to the spark eh? After all my tests on the spark I'd assume it's working fine. BUT I have not physically checked for spark yet... So as a free surefire way to make sure the spark is good, I will remove each plug, keep attached from the coil to the plug and setup a ground wire to the spark plug. I will physically check that each spark is sufficient before I completely rule out the spark.
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That proves that a plug with fire with no load on it. Cylinder pressure makes the coil work harder. The more pressure the more work. You need to test the coil under load. Even at idle the coil would see atlease twice the voltage demand then your test would require. Under driving load that would go to X4 quickly.
If the miss is shaking the car at 2000 RPM all the time you could borrow a infared heat gun and shoot exhaust manifold and see which one is not as hot or hotter then the others.
Last edited by Gorn; 08-27-2012 at 03:48 PM.
#44
Good call with the infared gun, ill give that a try. I guess the mist test isn't accurate enough? I have long tube headers btw
I also just got a compression tester and will be recording the cylinders pressure.
I also just got a compression tester and will be recording the cylinders pressure.
#46
Join Date: Nov 2007
Location: Eastern PA,
Posts: 10,387
FYI hotter = Lean and Colder = Miss fire or very rich.
If you can find which cylinder is acting up rotate the Coil, injector, Plug and wire to another cylinder and see if the miss follows. Of course do it one part at time. If nothing changes get your compression tester out. Also a vacuum tester can show a valve issue better than a compression tester depending on what is wrong with the valve.
I used this process back in the 80’s when my scope was broken with a hand help temp probe. It is still guessing compared to a scope but at least you are not throwing parts at it.
If you can find which cylinder is acting up rotate the Coil, injector, Plug and wire to another cylinder and see if the miss follows. Of course do it one part at time. If nothing changes get your compression tester out. Also a vacuum tester can show a valve issue better than a compression tester depending on what is wrong with the valve.
I used this process back in the 80’s when my scope was broken with a hand help temp probe. It is still guessing compared to a scope but at least you are not throwing parts at it.
#47
All header outputs read around 140-170 Celcius (yes I am Canadian)
EXCEPT for the one closest to the EGR valve. I think it's #2.
It was reading around 115-130 Celcius.
I am liking where this is going...
TIME TO TROUBLESHOOT!
EXCEPT for the one closest to the EGR valve. I think it's #2.
It was reading around 115-130 Celcius.
I am liking where this is going...
TIME TO TROUBLESHOOT!
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12-11-2007 06:49 PM