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OBD code 0300 multiple cylinder misfire?
I have a 1996 Firebird with the OBD code 300. Have done ohms test on coil packs = ok, all plugs and wires are new. What now?
Ignition module control has been checked also.
All sparks are good, too
Car runs rough especially upon idle. Engine is jumping and surging. Seems most likely a fuel pressure issue. Everything else has been tested. Gone down the probability list, on item at a time. Had this problem a year ago, blown head gaskets and bad coil packs, at that time. Soooo on we go...
4 Answers
- 1 decade agoFavorite Answer
i would go with the ignition module
test for spark while engine is running pull a wire off the coil one at a time dont pull it all the way off pull it back slowley to see hou far the spark will jump find the one that jumps the least and swap it with one of the others and retest of the low spark moved chage the coil as the insulation in it is bat if it didnt move change the ignition mobule also if you installed bosch platinium plugs get rid of them
- mrautomechanicLv 41 decade ago
You didnt say- how does the car run, does it run rough or not? A code Po300 is sometimes hard to diagnosis a good tech can usually figure it out though. Common problems are ignition failures, a intermittant stuck open EGR valve, low or weak fuel pressure, a bad fuel regulator, a vacuum leak, etc. Save money and pay a good technician a diagnosis fee, in the long run, you will be glad.
Source(s): 22 yrs ASE Master technician - bompianiLv 44 years ago
A misfire will enable unburnt air/gas which includes oxygen into the exhaust. The O2 sensor detects this oxygen and materials a pretend lean interpreting. fix the misfire first. generally a misfire is from undesirable plug wires. next is plugs, and next is coil %.. as quickly as you ensure the cylinder is getting spark, in case you however have a misfire, learn operation of the gas injector and cylinder compression.
