P0300 ramdom multiple cyclinder misfire. Please help

[Rohanmax14]

2004 Nissan maxima
New 2nd engine

I had 2 codes coming on will 1st code was (p1238) then i reseted cel n that code never came back. 2nd code is (p0300) this came at 20,000 mile on it on the engine.
When they put new 5 yrs old engine in the car won't crak at all so they clean or swap from old motor which was rod blown motor fuel injector n put it in new motor. That time we upgrade nitrous express 75 wet shot so shop put cheapest spark plug in my engine not ngk n they did not change coil iginition wire when they put new plugs.

So I got mis fire at 20,000 mile on those engine n I have not spray engine only 7 time in 20,000 miles on it.


The technosquare put my timing back to "stock" n
they said they don't reatrded the timing. N I called nitrous express 2 day ago they tld me if I'm going to run 75 shot then I'll be okay with my stock timing but I tld them I got mis fire after 20,000 miles n also tld them shop put cheapest plug in my engine. Nitrous express tld me we recommend using ngk colder plug.


The motor we found was at junk yard for 5 yrs.

After I got mis fire code I left the car at home cause I don't want my 2nd engine to blow.
Please help n sorry for my bad English. What can I do?

[MaximA32]

I would do what NX recommends as they have been doing this for a long time. If the engine has been sitting around for that period of time, I would definitely look at the ignition coils as they can go bad. There are only a few things that can go wrong to cause a misfire and that is one of them.

[Rohanmax14]

I would do what NX recommends as they have been doing this for a long time. If the engine has been sitting around for that period of time, I would definitely look at the ignition coils as they can go bad. There are only a few things that can go wrong to cause a misfire and that is one of them.

Can iginition coil can mis fire that code? I been getting rough gas meileage n finally after 20,000 mile later I got mis fire. The car crank n run I hope is not fuel injecotor or fuel pump?

I hope p1238 have nothing to do with this code cause I rested p1238 n is never came back expect p0300.

The code p1238= A/F sensor 1 bank 2 is that mean oxygen sensor if so which side?

[loystock]

P0300 is for multiple cylinder misfire and is likely due to usage of non-OEM plugs. Non NGK plugs can be problematic at times with Nissan/Infiniti engines. So instead of replacing the coils (expensive), change the spark plugs first. You have a choice of Platinum (NGK PLFR55A-11 @ $1 ea.) or Iridium (LFR5AIX-11 @ $8 ea.). Both of these plugs are for normal heat range (5). Since you are using NOS, it would be better to go for a colder plug (heat range 6, e.g. PLFR6A-11) so as not to overheat the plugs (engine). Depending on your NOS usage, you may even need heat range 7 to absorb the extra heat generated as a result of the NO spray. Bear in mind that the spark plug not only ignites the fuel-air mixture, it's also used for heat transfer.

While you are replacing the plugs, it would also be a good idea to clean and re-secure the main engine harness ground points as poor connections can also cause a misfire.

P1238 refers to Fuel Pump Secondary Circuit Malfunction but is not listed in the 04 Maxima trouble codes. The description you have, "A/F Sensor 1 Bank 2" is actually for DTC P1283 and not P1238. If indeed you have P1283, Bank 2 is for the front cylinders (2-4-6) and Sensor 1 means FRONT O2 (air flow) sensor. So follow the front exhaust manifold (towards radiator) and you should be able to find the front sensor by the Pre-Cat area.

[Rohanmax14]

P0300 is for multiple cylinder misfire and is likely due to usage of non-OEM plugs. Non NGK plugs can be problematic at times with Nissan/Infiniti engines. So instead of replacing the coils (expensive), change the spark plugs first. You have a choice of Platinum (NGK PLFR55A-11 @ $1 ea.) or Iridium (LFR5AIX-11 @ $8 ea.). Both of these plugs are for normal heat range (5). Since you are using NOS, it would be better to go for a colder plug (heat range 6, e.g. PLFR6A-11) so as not to overheat the plugs (engine). Depending on your NOS usage, you may even need heat range 7 to absorb the extra heat generated as a result of the NO spray. Bear in mind that the spark plug not only ignites the fuel-air mixture, it's also used for heat transfer.

While you are replacing the plugs, it would also be a good idea to clean and re-secure the main engine harness ground points as poor connections can also cause a misfire.

P1238 refers to Fuel Pump Secondary Circuit Malfunction but is not listed in the 04 Maxima trouble codes. The description you have, "A/F Sensor 1 Bank 2" is actually for DTC P1283 and not P1238. If indeed you have P1283, Bank 2 is for the front cylinders (2-4-6) and Sensor 1 means FRONT O2 (air flow) sensor. So follow the front exhaust manifold (towards radiator) and you should be able to find the front sensor by the Pre-Cat area.

If i didn't get p1238 code back then is that mean I still have problem with my Fuel Pump Secondary Circuit Malfunction? Y didn't that code came back yet?

[Rohanmax14]

Sorry guys the title is "P0300 Ramdom multiple cyclinder mis fire".

U mean ecu ground wire connection?

[loystock]

I'm referring to the main engine harness ground points (2 ea). They provide grounding for the ignition coils, fuel injectors, etc. In the 6th Gen Maxima, I think they are located close to the oil filler cap area. Clean the lugs and frame/slots where they are bolted on and apply dielectric grease to prevent corrosion.

BTW, I made a typo, the NGK platinum plug is $12 ea.

As for the P1238/P1283, make sure you get the right trouble code if it comes back.

[Rohanmax14]

I'm referring to the main engine harness ground points (2 ea). They provide grounding for the ignition coils, fuel injectors, etc. In the 6th Gen Maxima, I think they are located close to the oil filler cap area. Clean the lugs and frame/slots where they are bolted on and apply dielectric grease to prevent corrosion.

BTW, I made a typo, the NGK platinum plug is $12 ea.

As for the P1238/P1283, make sure you get the right trouble code if it comes back.

idk where's engine main harness ground is located. If we can find picture of it that'll be wonderful.

I need this plug for my nos n gap them to .35
http://ngk.com/results_cross.asp?pid=lfr6aix-11

let me double check about what code did I get about p1238/p1283.

[Rohanmax14]

Sorry guy is was p1283 code.

[Rohanmax14]

Check out vid on bottoom

http://www.youtube.com/watch?v=mG6C8D3Sg00

is this 02 sensor u talkng about if so can I take it out n clean it? Which cleaner will do best place I can get them at autozone.

[loystock]

Go to page EC-486 from the attached link to see the ground points and location and Bank 2 Sensor 1. The O2 (air flow) sensor is typically replaced when it fails. I have had no luck in cleaning them to make them work again. You can get the O2 sensor also from NGK.com.

BTW, the NGK spark plugs are pre-gapped to 0.044 (-11 in the part number). It's not a good idea to adjust the gap as it can damage the center electrode.

http://www.nicoclub.com/FSM/maxima/2004/EC.pdf

[Rohanmax14]

Thank man great information. How did u found that?

Ngk tld me to gap plug to .35th with ngk colder plug.

[Rohanmax14]

Update:: we changed the 02 sensor A/F sensor 1 bank 2. They was 2 different color shown on 02 sensor n is was white n dark brown. After that engine stop shaking n it run better.

We clean MAF sensor. We also look at coil wire n spark plug none of them shown bad sysmbol. We check fuel pressure is was at 50 psi n fuel injector is in good condition.

Why did that happen n what make 02 sensor go bad?

The gap of plug is .44 n don't I need to gap it too .35 for nos? Can it hurt my engine if I'm spraying with .44 gap?