00 deville P0300 - runs like crap

[lowsixfo64]

so im driving home from work on Friday and i feel a slight misfire or whatever. So my 00 deville with 70k continued to run like crap. I put a scan tool on it and its only telling me that i have a misfire. im not sure of the cylinder. I suppose i could pull the injectors one by one. I replaced the plugs about 20k ago and just checked the fronts today. everything seems fine. The egr seems good and all sensors seem to be working.

Any help or ideas?

[MAC]

I would first check for a vacuum leak and make sure intake manifold bolts are not loose. Then make sure wires are good--I would do the nightime open the hood check to see if there is any electrical arching. If all is fine I would guess that the P0300 code could be related to a defective coil, which is an easy fix.

[lowsixfo64]

I would first check for a vacuum leak and make sure intake manifold bolts are not loose. If all is fine then I would hazard a guess that the P0300 code could be related to a defective coil, which is an easy fix.

are those thing expensive?

[MAC]

I would first check for a vacuum leak and make sure intake manifold bolts are not loose. If all is fine then I would hazard a guess that the P0300 code could be related to a defective coil, which is an easy fix.

are those thing expensive?

It is fairly expensive ($188 for ACDelco coil) because it looks like you can't purchase a single coil pack. But check to make sure the wires are good before you go out and buy a coil. If a wire is arching/leaking it could be the problem. But then again, a new set of wires won't be cheap either--but at least they would be less expensive then a new coil.

[lowsixfo64]

they are plugs into the coil packs...do they go bad?

[MAC]

they are plugs into the coil packs...do they go bad?

If you're referring to spark plug wires which plug into the coil, then yes, they can deteriorate and cause misfiring.

[Bruce Nunnally]

Here is one of the diagnostic tables for engine miss with no internal engine noises:

Base Engine Misfire without Internal Engine Noises

Cause	Correction
Abnormalities, severe cracking, bumps, or missing areas, in the accessory drivebelt Abnormalities in the accessory drive system and/or components may cause engineRPM variations and lead to a misfire DTC. A misfire code may be present without anactual misfire condition.	Replace the drive belt. Refer to Drive Belt Replacement .
Worn, damaged, or mis-aligned accessory drive components or excessive pulleyrunout and may lead to a misfire DTC. A misfire code may be present without an actual misfire condition.	Inspect the components, repair or replace as required.
Loose or improperly installed engine flywheel or crankshaft balancer A misfire code may be present without an actual misfire condition.	Repair or replace the flywheel and/or balancer as required. Refer to Engine Flywheel Replacement or Crankshaft Balancer Replacement .
Restricted exhaust system A severe restriction in the exhaust flow can cause significant loss of engineperformance and may set a DTC. Possible causes of restrictions include collapsed ordented pipes or plugged mufflers and/or catalytic converters.	Repair or replace as required.
Improperly installed or damaged vacuum hoses	Repair or replace as required.
Improper sealing between the intake manifold and cylinder heads, intake manifoldand plenum duct, plenum duct and water crossover, water crossover and throttle bodyand/or pressure relief valve and intake manifold.	Replace the intake manifold, plenum duct, gaskets, cylinder heads, throttlebody and/or pressure relief valve as required.
Improperly installed or damaged MAP sensor and/or seal The sealing grommet of the MAP sensor should not be torn or damaged.	Repair or replace the MAP sensor as required.
Improperly installed or damaged EVAP purge solenoid and/or O-ring seal	Repair or replace the EVAP purge solenoid as required.
Worn or loose followers, valve rocker arms The follower, valve rocker arm, roller bearing should be intact and in the properposition	Replace the followers, valve rocker arms, as required.
Stuck valves Carbon buildup on the valve stem can cause the valve not to close properly.	Repair or replace as required.
Excessively worn or mis-aligned timing chain or chains	Replace the timing chain or chains and sprockets as required.
Worn camshaft lobes	Replace the camshaft or camshafts and SHLAs, valve lifters.
Excessive oil pressure A lubrication system with excessive oil pressure may lead to excessive valvelifter pump-up and loss of compression.	• Perform an oil pressure test. Refer to Oil Pressure Diagnosis and Testing . " • Repair or replace the oil pump as required.
Faulty cylinder head gaskets and/or cracking or other damage to the cylinderheads and engine block cooling system passages. Refer to Diagnostic Starting Point - Engine Cooling in Engine Cooling. Coolant consumption may or may not cause the engine to overheat.	• Inspect for spark plugs saturated by coolant. Refer to Spark Plug Inspection in Engine Controls. • Inspect the cylinder heads, engine block, and/or head gaskets. • Repair or replace as required.
Worn Piston Rings Oil consumption may or may not cause the engine to misfire.	• Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection in Engine Controls. • Inspect the cylinders for a loss of compression. Refer to Engine Compression Test . • Perform cylinder leak down and compression testing to identify the cause. • Repair or replace as required.
A damaged crankshaft reluctor wheel A damaged crankshaft reluctor wheel can result in different symptoms dependingon the severity and location of the damage. • Systems with SEVERE reluctor ring damage may exhibit periodic loss ofcrankshaft position, stop delivering a signal, and then re-sync the crankshaft position. • Systems with SLIGHT reluctor ring damage may exhibit no loss of crankshaftposition and no misfire may occur. However, a P0300 DTC may be set.	Replace the crankshaft as required.

[lowsixfo64]

alrighty today is the day. thanks guys

[Ranger]

The 2000 started COP (Coil On Plug) ignition. There are no wires.

[Logan]

These cars are different....

The coils are set in banks. You cannot replace a single coil. No plug wires..

There are 'boots' between the coil and plug. These can go bad also.

Anyway, I carry a spare in the trunk. I have 2 spare coil banks from eBay.

There are 2 versions. A 'silver' front and 'black' rear bank. Stupid cost wise...they are interchangable. That being said, some years have a different setup for 'how' the IC module plugs in..