My G/F has a 2001 Mazda B3001 w/auto trans. When the truck is started after sitting for a while it miss for about a minute or less and throws a P0301 code; misfire in #1 cylinder. After a minute or two it runs great!!! I will clear the code and it does not miss and the code does not show up until she starts it again. I Put some new plugs, change fuel filter, check the electrical connector on #1 injector and checked the plug wires. Still throws the code. I swapped #1 and #2 plug wires to see if the code changes but will have to wait till the AM. Any thoughts on this one???
GNORMOR

 

You've been busy on this one.

If swapping the plug wires doesn't cause the code to follow, maybe put the #! fuel injector on the suspect list, along with a sticking valve if there is noise from the engine when it's missing.

How did the old #1 plug read when removed & compaired to the others????

Maybe consider a cold compression check on #1 if you hear anything from the engine.

If you come to suspect the fuel injector, listen to it with a stethscope on a cold start when it's missing, to determine if it sounds match the miss, or if it sounds different from the others.
If it does, maybe consider installing a noid light in it's electrical connector & watch the blink to see if it's an electrical problem.
The injectors electrical resistance should closely match the others & it should have steady B+ to it at KOEO.

If you come to suspect a dirty, sticking injector, or intake valve, maybe consider a good tidy upper, like a 20oz dose of Chevron Techron Concentrate Plus at the pump, before filling up & see if you get any positive change in the miss.

During the treated tank, give it several good blow it out high rpm sessions for 2-3 miles of rpm's above 3500, to remove carbon deposits on the intake valves & combustion chamber, that the Techron has loosened up & see what happens.

If things get better but don't completely clear up, do a second treatment.

If no joy, you could pull the #1 injector for inspection & if that doesn't show anything, maybe do do an injector swap & see if the misfire code follows.

If you come to suspect a varnished up intake valve is sticking, maybe consider a good high detergent motor oil that claims to remove deposits, like a high mileage recipe, or maybe one of the new Pennzoil GF-5 detergent recipies like the yellow bottle pennzoil & see if it'll remove enough varnish to free things up.

A bunch more thoughts for consideration, let us know what you find.

 

Code tis morning was still 301. I agree it about the injector. Project today is investigate number #1 and go from there. Thanks for the reply.

 

dump a 20 gallon bottle of Techron in the tank........

 

Took the truck to the DEALER and they had it for a day and half, G/F called and they quoted her a bill of $1000.00!!! They could not find the problem per say but up dated the calibration (okay) wanted to replace the new (less then 50miles) spark plugs said the Autolite Double Platumims were not as good as the Motorcraft. I think both are made by Honeywell. Wanted to clean the K&N air filter, replace the new fuel filter (50 miles) replace the air snorkel from the filter to the manifoil (had a hole but I sealed it up), and a few other items that were common to the complete air/fuel system. Oh and they wanted to flush the fuel system, that I said okay to that. I nixed everything but the flush. I'm new to the San Antonio area but I need to find me an indepentent mechanic. We get the truck back this afternoon and will see if the 301 code still pops up. Oh yeah and they wanted to replace my 3 month old 8mm Accel plug wires too!!!