P0300 Help
 

Hello again all.

So after fixing the P0170 and P0125 on the 2001 Montero Limited, this came up. I wanted to change the fuel injection regulator but I wanted to get some guidance first.

Here's the freeze frame.

Fuelsys1 - CL
Fuelsys2 - CL
Load_pct(%) ----> 23.5
ECT(*f) ----> 88
ShrtFt1(%) ----> 3.9
LongFt1(%) ----> 12.5
ShrtFt2(%) ----> -5.5
LongFt2(%) ----> 4.7
RPM (/min) ----> 1824
VSS(mph) -----> 0

Thanks in advance!

You are still having some issue on bank 1. Your total fuel trim on bank 1 is +16.4%. It is not causing the issue with the missfire, but something is still out of balance compared to bank 2 (nearly 0% fuel trim = perfect). Random misfires are a pain in the rear to diagnose. Here are the items to check:
Spark plugs - right kind? Torqued to spec?
Spark plug wires - are they seated properly on the plugs?
Connectors on the back of ignition coils - any missing tabs? If so, it would allow connector to move and cause a missfire.
Exhaust leak (cracked exhaust manifold on bank 1)
Other possible culprits:
Camshaft position sensor malfunction.
Timing belt off a little. Did you have any work done on timing belt recently?

Thanks Hunter for the list. I'll check the connections again. The previous owner did have the timing belt done before I took ownership. Funny thing though is I was able to drive around for about a week and even got smog to go through. After I drove it on the freeway for about 70 minutes then it gave me a code on the restart. It seems to get rough on the startup when cold.

I was thinking of getting the spark plugs changed cause it looks like it would be a pain to do. It does have new wires by the way. It even wanted to change the coils since its pretty cheap. Only question is, is that easy enough to do? I haven't checked their locations. I'll start with that and lead to the timing belt. I hope that's not it.

Coils will be easy, they are right up on top and front of the engine. Before you replace them, just check the connectors.
If you are able, definitely check timing belt. If it is off by one tooth, you'd be able to drive almost without issues, but the random misfire is likely to occur.
When you do decide to dig in and change the spark plugs, I would seriously recommend sticking with the Iridium Plugs (not generic standard plug type). The location of the plugs on Montero is such, that you don't want to get in there any more frequently than you absolutely have to (50-60k miles). The standard plugs will need to be replaced more frequently while the Iridium plugs last forever.

Cool. The coils look secure as well as wires so I'll have my mechanic check the belt. I really do want to change the spark plugs. I should have when they did the injectors. I forgot about it.