2.7 L Questions/Possible Head Gasket

Hello,

I just recently purchased a used Tacoma with 191K on the clock. It seems to run strong but started throwing P0300, P0301, P0302 codes right after I bought it. I replaced the spark plugs (had cheap autolites) and coil packs - both plugs and packs are Denso. It ran great for a couple of weeks and then I did a water pump, thermostat change out, pulled the cooling system down to 24"hg and installed new coolant.

Now P0300, P0301, and mostly P0302 is coming back on when it's cold. It is idling super rough until I clear the codes. I have done the following 1. Swapped plugs, coils, and injectors around with cylinders 3 and 4. 2. Did a compression check: Cylinder 1: 130 psi, Cylinder 2: 122 psi, Cylinder 3: 130 psi, Cylinder 4: 135 psi.
Observations: 1. The coolant reservoir tank was low when I bought it (so not really sure of coolant loss) 2. Oil and coolant do not look milky. 3. Checked the oil and was 1 quart low after 600 miles. 4. Oil fill cap has foamy latte looking film after running.

Does the above indicate a head gasket failure (probably between cylinder 1 and 2)?

 

Replace the spark plug tube gaskets. Good luck!

 

Oh yeah forgot to mention I did that along with the valve cover gasket. thanks.

 

What coils did you buy?

 

They are Denso OEM coil packs.

 

Shit. Oe plugs? You bought the coils at Toyota?

 

Yup - Denso as well. Plugs look fine after 600 miles, no oil, rust, etc. just clean.

 

@Dm93 might have a clue. I ain’t buying the hg but who knows.

 

Being it only misfires on a cold start kind of would suggest a headgasket that is seeping coolant in one or more cylinders, the way to check would be to pull the plugs, pressurize the cooling system, allow it to sit several hours or overnight, then look in each cylinder with a borescope for coolant.

 

When I did the compression check I looked down the bore of each cylinder, cylinders 1&2 looked wet while 3&4 appeared dry. Funny since I swapped around the plugs, coils, and injectors I didn't get any codes today...I would be surprised if they don't reappear. The codes and oil consumption have me wondering.

 

130 PSI is low. But since it's even in all cylinders, this shouldn't be the issue. But that's definitely low. "Good" should be over 160.

Are you sure the gauge is good?

"Foamy latte" oil cap typically either means it's not reaching operating temp for long enough (only short drives), or an internal coolant leak.

Take it to a shop and have them do a sniffer test on the open radiator to check for exhaust gases.