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Seems I have a misfire on one or more cylinders. Doesn’t happen all the time (yet). I’m sure it probably a coil going bad as I have had that problem before. However this time there is no check engine light and in the past with a bad coil, It misfires horribly not just occasionally. Any ideas on how to start locating the problem if this is indeed the issue?
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Try doing a power balance test.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
A power balance would be a good place to start as College man pointed out. This way you can narrow down an offending cylinder(s) if you have one. There is additional information in the article he posted that you may also find helpful.
Keep us posted on what you find.
Strangely enough, I had a starting issue shortly after the misfires. When I made it home I thoroughly cleaned the battery cables as they were corroded. I now have not had a problem with misfires today. Can a poor battery connection cause a misfire? I put the engine under a load to try to reproduce the misfire as I did before, now no misfire.
Yes it can. System voltage is extremely important to the fuel injection system. The system communicates in the language of voltage. If you start with less voltage, everything will be off and everything will be effected. It’s like trying to talk with a rag in your mouth.
Ok the misfire /bump in the engine continues. No engine light or code is showing. Sometimes when almost coming to a stop or starting at a red light, there will be a single thump that can be felt. When the engine is under heavy loads it can be felt frequently. I did the parking brake put it in drive and floor it test. It feels like a bad coil when doing this but rarely does it at all while idling. I did a power balance test and everything checks out. I hate to have to spend the money to have this diagnosed. I know I could fix it if I knew where to start. It doesn’t seem to happen when the engine is cold, but after I drive it a few miles. Also have a leak in my gearbox of the power steering rack. Do I just need to top it off and Roll on until it begins to fail or should I go ahead and replace it?
Any help greatly appreciated!
When was the last time the plugs were changed? May want to get a look at them…
Also, ensure your battery connections are clean and tight…Can’t say this enough and should be holding at least 12.6 volts after you have taken it for a 15-20 minute drive and shut it off… Also may want to check how well the alternator is charging…
May want to try a power balance test with your fuel injectors… unplug each one, one at a time from the electrical harness, kinda the same way you did with the COPS. Also see if they are all clicking, use a mechanics stethoscope or a long screwdriver to you ear with the working end on the fuel injector. Sometimes just tapping lightly on an injector can get it clicking again… Maybe your injectors are dirty/clogged.
Also may want to check the fuel injector wires individually with a noid light… may need to also get fuel pressure checked..
Kinda throwing it all out there…
-Karl
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