P0300 and P0302 Initially, Now Runs Rough But No Codes

[denvermaxd]

On Friday last week I picked up my 2000 SR5 manual from the tire shop. Got home, realized I forgot something, and jumped back in the truck, but as soon as I started up and began to roll I could tell there was something wrong. Engine felt rough and with a manual you can really tell when there's a power loss.

A few minutes later, check engine light came on. P0300 and P0302. Interestingly enough, once I got on the gas to merge into traffic I felt the roughness disappear and had full power. Truck ran fine after that for about 10 miles and 2 trips.

Then yesterday, ran to the store and after about 20 minutes was back in the truck.

Started up, and again engine was rough, but this time, no codes. Drove about 6 miles home, rough all the way, no codes, no check engine.

Last night I pulled the spark plug from the #2 cylinder and everything looked good. These plugs have about 20,000 miles on them, and I do have a supercharger so it can be hard on plugs.

Ordered new plugs anyway, and am going to run Lucas lube and injector cleaner tonight.

My question at this point is: Does the sporadic nature of the performance degradation, and the fact that it only comes on when the truck is "hot started" give any hints as to whether it is:

• Plugs
• Wires
• Injectors
• Coil packs
• Head

 

[dirty monkey]

wrong generation.

Do a Blown head gasket test.

 

[Buckaroo]

On Friday last week I picked up my 2000 SR5 manual from the tire shop. Got home, realized I forgot something, and jumped back in the truck, but as soon as I started up and began to roll I could tell there was something wrong. Engine felt rough and with a manual you can really tell when there's a power loss.

A few minutes later, check engine light came on. P0300 and P0302. Interestingly enough, once I got on the gas to merge into traffic I felt the roughness disappear and had full power. Truck ran fine after that for about 10 miles and 2 trips.

Then yesterday, ran to the store and after about 20 minutes was back in the truck.

Started up, and again engine was rough, but this time, no codes. Drove about 6 miles home, rough all the way, no codes, no check engine.

Last night I pulled the spark plug from the #2 cylinder and everything looked good. These plugs have about 20,000 miles on them, and I do have a supercharger so it can be hard on plugs.

Ordered new plugs anyway, and am going to run Lucas lube and injector cleaner tonight.

My question at this point is: Does the sporadic nature of the performance degradation, and the fact that it only comes on when the truck is "hot started" give any hints as to whether it is:

• Plugs
• Wires
• Injectors
• Coil packs
• Head

Since your P0300 indicates multiple cylinders, first thing I would do is inspect your inlet air ducting and verify it doesn't have any cracks/loose clamps. Then I would clean the MAF.

Have seen the hot miss condition associated with bad injectors & coils on 3rd gen. Because this is a waste spark system, the coil on cylinder 2 feeds cylinders 2 and 5 so could see P302 and P305. You could swap the coil from #2 cylinder to another cylinder and see if the missfire moves to it or it's paired cylinder. If it doesn't move, swap the injector to another cylinder.

Some thoughts on tracking down the misfire...

https://www.toyota-4runner.org/3rd-gen-t4rs/234290-maddening-misfire-mystery.html

 

[denvermaxd]

Sorry I put this in the wrong forum. Not sure how that happened, but I was battling the platform (changed my email and was blocked from all posting) so I must have just clicked wrong.

I'll try the measures in recommended here and in links and see what happens.

It's definitely a "hot start" issue. Happened again last night. Truck runs great from a cold start, but if it sits for 1-30 minutes after running, the restart always results in an ongoing misfire.

Strangely, no check engine light or codes, though.