[Fisherman466]

Hi everyone, I'm scratching my head on this one. Any feedback or suggestions would be great, I'm about to give up and hand it to a shop.

I have a intermittent misfire that occasionally throws a P303/P304 and a blinking MIL. After letting my truck sit for 15-25 minutes my truck will misfire on startup. It will misfire for a minute (MIL is blinking during this) and then run fine. During cold starts there is no issue, only after letting it sit for 15-20 minutes after running it. The only other symptom is a rough idle when the engine is warm. The idle does get progressively rouger after driving and then letting my truck idle.

So far I have tested:

Fuel injector ohms, all are 1ohm over spec. I have pulled the passenger side injectors at idle and the truck did idle rough as expected. Could not access driver side connectors.
There was 4 vacuum hoses that I replaced that were leaking. Can't find any more.
Spark from distributor is very strong
Ignition timing is at 10°


So far I have replaced:

Spark plugs.
Plug wires.
Distributor.
Front 02 sensors.
Cleaned MAF (good values on scanner)
Intake air temperature sensor.
Fuel filter.

The only thing that I could think of at this point would be bad Injectors or a bad fuel pump. I have not been able to test pressure yet but will soon. No excessive oil consumption or coolant loss. I'm honestly lost on this.

And also 02 Frontier, VG33E

 

[beemer]

Hi everyone, I'm scratching my head on this one. Any feedback or suggestions would be great, I'm about to give up and hand it to a shop.

I have a intermittent misfire that occasionally throws a P303/P304 and a blinking MIL. After letting my truck sit for 15-25 minutes my truck will misfire on startup. It will misfire for a minute (MIL is blinking during this) and then run fine. During cold starts there is no issue, only after letting it sit for 15-20 minutes after running it. The only other symptom is a rough idle when the engine is warm. The idle does get progressively rouger after driving and then letting my truck idle.

So far I have tested:

Fuel injector ohms, all are 1ohm over spec. I have pulled the passenger side injectors at idle and the truck did idle rough as expected. Could not access driver side connectors.
There was 4 vacuum hoses that I replaced that were leaking. Can't find any more.
Spark from distributor is very strong
Ignition timing is at 10°


So far I have replaced:

Spark plugs.
Plug wires.
Distributor.
Front 02 sensors.
Cleaned MAF (good values on scanner)
Intake air temperature sensor.
Fuel filter.

The only thing that I could think of at this point would be bad Injectors or a bad fuel pump. I have not been able to test pressure yet but will soon. No excessive oil consumption or coolant loss. I'm honestly lost on this.

And also 02 Frontier, VG33E

Did you ever figure it out?

 

[Fisherman466]

Did you ever figure it out?

Maybe, I replaced four vacuum/pcv hoses that were leaking. The engine ran better afterwards but still had the same issue.

I replaced all injectors except for cylinder five and upon startup it was running extremely rough, billowing smoke, and other things but did stop.

I stopped driving the truck mostly after that but did not have the issue come up. I recently sold the truck and moved on. It could have been an injector. But I also could of not have had enough time for it to trip a code again.

 

[bwthor]

Had an identical issue that turned out to be an injector too. Never happened on cold starts, only after it was up to temp, and I restarted after sitting for a few minutes. Would miss at restart, and go away anywhere from 5 seconds to up to a minute. Replaced with a junk yard injector and has been running fine since. There are colored dots on the injectors by the plug, so if you are looking, make sure to get the correct ones.