still misfires new code now troubleshooting help

Hi I have 99 tacoma with 445600 miles on it. I have a misfire p0301. I changed spark plugs, coils, and wires and 1 fuel injector on cylinder 1 I also recently did a compression test cylinder 1 was at 158, all others around 170 and I had another code p0420 runs fine at speed but hard to start and idle what should I troubleshoot next all advice greatly appreciated thanks

 

Have you confirmed you have spark?
You can also buy a Niod light tester for the injector to check signal/fire.

 

ok thanks I will check for spark

 

Has spark Maf sensor seems high at idle 12g/s maybe bad sensor??

 

Do you have a scantool that can read live data?

it could be the maf but that would almost surely affect all cylinders and throw different codes... I would backburner the maf for now and get a noid light or rig in an incandescent test light to the injector to ensure it's actually firing it

 

put new injectors wires coils plugs so I gonna check maf sensor any other ideas truck still has power gonna check fuel.trim next will post data once I get it

 

Those 2 codes still pending after injectors/coil p’s/wires/plugs installed?

 

yes

 

Was the #1 cyl plug dry/white?
Let’s say different condition than others?

 

yes plug still white dry

 

truck still runs fine at speed idle is low and burns more fuel

 

cleaned maf earlier no change

 

compression was 158 in cylinder 1 all others around 170

 

IMO
The MAF measures and then sends signal to PCM that sends same signal to all injectors.

I think need to dig deeper into that #1 cylinder. Specifically the head’s valves on #1.
Leak down test or borescope thru plug hole or compressed air thru #1, turn crank bolt by hand starting at TDC and litsen. If you hear a hiss thru air box….intake valve not seating
If you hear hiss thru tailpipe….exhaust valve not seating

 

ok thanks for advice probably gonna order maf sensor as well truck has 445600 miles on it so need to get back running good and will work on it after rain stops another hurricane

 

Wait wait, you replaced an injector but do you have a power pulse to the injector... if you don't have a pulse at the injector then you can fire the parts cannon all you want with no change

 

how do you test to see if you have a power pulse to injector? multimeter?

 

I have used this with success
Unsure my dizzy was getting power….showed getting power

Non contact voltage tester
Like $5 at harbor freight

 

ok thanks

 

@boodacrf450 did you ever solve this issue? I have the same issue with mine!
Compression test seems fine Im getting a rich bank 1 also
I also puchased a new IAC valve for mine.
Cleaned the MAF sensor