Rough Running When Cold Fine When Warm

Hi. I have a 2003 Tacoma with the 2.7 engine. I have the same issue on a daily basis. When I start the engine in the morning it runs rough and I get a 301 code. After the truck warms up and I reset the code, the truck runs great for the rest of the day. I recently replaced all four spark plugs and coils. Any suggestions? Thanks!

 

google says 301 is cylinder misfire so did you have this issue before replacing the coils? even new coils can be bad or have cracked insulator right out of the box.

if you had the problem before then did you also replace the insulator boots?

 

Did you gap your plugs correctly?

 

I had the exact same problem before I replaced any parts. Before replacing the coils I ordered and installed replacement boots but since they were original I went and replaced them as a precautionary measure. I swapped coils with other cylinders first, before any other work. I gapped the plugs properly.

 

hopefully this can help http://troubleshootmyvehicle.com/toyota/1.8L/how-to-test-misfire-codes-1

 

That's odd. Almost sounds like a compression issue.

 

I would think injector issue because you either have compression or you don't but it could be lots of things

 

Swap injectors

 

Are you losing any coolant? I've seen trucks have bad head gaskets allowing coolant to seep into the cylinder over night. fire it up in the morning and it misfires for a while until it warms up and everything expands and the gasket seals up again....

 

spark plug wires possibly...my 3.4l was doing this same thing, mostly after moisture events (rain, heavy dripping fog) and left overnight....changed plugs, no luck, put in new set of NKG wires, problem solved....

since it is isolated to #1 cylinder, swap coil packs and see if miss code changes to 302, 303, etc...

just some thoughts...good luck with trouble shooting...

 

I checked the coolant overflow container, added a little and marked the side of the container. I'll keep an eye on it.

 

even if you have no leaks in the cooling system, the over flow will need occasional refilling/topping off just from evaporation, the canister lid is far from air tight...

obviously, if you have to refill once a week, you gots a problem, but if you live in a hot environment, it would not be unusual to have to top it off a couple of times during the hot summer months...

 

I was having the exact same problem after wet nights on my 3.4l seemed to just be corrosion on one of the coil extension tubes.