Help, Replace Spark Plugs and Coils P0303

[JayOoz]

Hello, I got a code for P0303, I Changed the spark plugs and tested the coil they are good, the Code P0303 still pop up.
Im running PRL cobra Race manufactor. Would that void my warranty? Im only at 38k.

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[DRUSA]

Hello, I got a code for P0303, I Changed the spark plugs and tested the coil they are good, the Code P0303 still pop up.
Im running PRL cobra Race manufactor. Would that void my warranty? Im only at 38k.

Have the dealer run a a/f cylinder balance test (injector test) on the vehicle. We've had lots of injector batches going bad. They run rich and lean, they should be covered under warranty 5yr/60k miles.

 

[KOIVUN1]

Have the dealer run a a/f cylinder balance test (injector test) on the vehicle. We've had lots of injector batches going bad. They run rich and lean, they should be covered under warranty 5yr/60k miles.

have you seen my posts in the tuning thread as well as my engine stutter on cold start thread? i'm fairly certain that it's my injectors, but i wont know from the dealer until at least the 17th.
i found another guy who had exact same issue as me, misfires only on cold start, and his fix ended up being the injectors.
it's very curious though why it only ever misfires on cold start. for me even warm starts, like 2-4 hours after parking the car it will be very stubborn. i have to try and coax it to smooth out or wait for the p030X code to pop up, turn the car off, clear code(s), and try again.
i strictly use coscto 93 (Mobil gas i believe), so gas quality shouldn't be an issue, and i have 16k miles so buildup of any kind is unlikely i think.

 

[JayOoz]

Have the dealer run a a/f cylinder balance test (injector test) on the vehicle. We've had lots of injector batches going bad. They run rich and lean, they should be covered under warranty 5yr/60k miles.

Thank you, I will definitely take it to the dealer tomorrow.

Just wanted to make sure i got this right,
The ignition coil numbers when looking from the front bumper to back bumper is 4321 or 1234?

 

[DRUSA]

It runs like @ss during cold start because the engine is in open loop, it's running off of a warm up map. Once it warms up it switches over to a closed loop map and starts looking at the oxygen sensor and starts adjusting the fuel trims to make it run better.

 

[DRUSA]

Thank you, I will definitely take it to the dealer tomorrow.

Just wanted to make sure i got this right,
The ignition coil numbers when looking from the front bumper to back bumper is 4321 or 1234?

The coils are 1234 when viewed left to right with the hood popped and looking at the engine contemplating life choices.

 

[JayOoz]

have you seen my posts in the tuning thread as well as my engine stutter on cold start thread? i'm fairly certain that it's my injectors, but i wont know from the dealer until at least the 17th.
i found another guy who had exact same issue as me, misfires only on cold start, and his fix ended up being the injectors.
it's very curious though why it only ever misfires on cold start. for me even warm starts, like 2-4 hours after parking the car it will be very stubborn. i have to try and coax it to smooth out or wait for the p030X code to pop up, turn the car off, clear code(s), and try again.
i strictly use coscto 93 (Mobil gas i believe), so gas quality shouldn't be an issue, and i have 16k miles so buildup of any kind is unlikely i think.

Mine started two days ago. It was hot in Central valley (Merced). So i don't think the cold was tthe problem.

The coils are 1234 when viewed left to right with the hood popped and looking at the engine contemplating life choices.

Okay, Thank you.

I just checked my Hoses and everything

is this suppose to look like this?

 

[DRUSA]

Mine started two days ago. It was hot in Central valley (Merced). So i don't think the cold was tthe problem.


Okay, Thank you.

I just checked my Hoses and everything

is this suppose to look like this?

Hose is fine. That is an overflow hose for the coolant reservoir, it's supposed to be like that.

 

[JayOoz]

Hose is fine. That is an overflow hose for the coolant reservoir, it's supposed to be like that.

Okay, I also notice the Temp on my car is going up faster than usual whenever i start the car. Normally it will take a while to warm up but it was warming up pretty quick.

 

[KOIVUN1]

Mine started two days ago. It was hot in Central valley (Merced). So i don't think the cold was tthe problem.

i was asking DRUSA haha although we very well may have the same issue

i was talking not about weather temps lol. be it 70 or 90 out it's still cold for oil in an engine
i meant just cold/warm starts usually. if i parked for a trip to the store it would behave upon startup. if i started it in the morning say at 70 degrees out, ect under 100 it would be a rough idle for a handful of seconds, but even ect 140-165 it would still be idling rough

report back with how the a/f cylinder balance injector test goes.
i'll only be able to report back with info on or after the 17th. lucky me gets to worry about my car from hawaii for 10 days

 

[JayOoz]

i was asking DRUSA haha although we very well may have the same issue

i was talking not about weather temps lol. be it 70 or 90 out it's still cold for oil in an engine
i meant just cold/warm starts usually. if i parked for a trip to the store it would behave upon startup. if i started it in the morning say at 70 degrees out, ect under 100 it would be a rough idle for a handful of seconds, but even ect 140-165 it would still be idling rough

report back with how the a/f cylinder balance injector test goes.
i'll only be able to report back with info on or after the 17th. lucky me gets to worry about my car from hawaii for 10 days

Yea, i think we may have the same issue. It started when i got onto a highway kinda was a rough start also. yes, Please do because ill have to take mine in tomorrow and see what they will report back. If mind get done first ill report it back on here.

 

[gtman]

Here's some detailed info on diagnosing those misfire codes from D-Rob himself.

"Misfires and You - a.k.a. How to diagnose your P0300 (301, 302, 303, 304) codes.

Plugs, coils, injectors, valve lash, head gasket, ringland. Those, in that order, are the most probable causes of misfire conditions on L15 engines.

Plugs are pretty self explanatory; I've seen fouled plugs, broken porcelain (where it will be broken and slide up and down the electrode when shaken), etc. If the misfires occur only under high load at elevated boost pressure or in colder weather, the default spark plug gap may be too wide. In that instance, reducing the plug gap down to 0.020-0.025" will solve the problem.

Coils; self explanatory here again. Coils fail and you can diagnose this by moving the coil to another cylinder to see if it moves with it.

Injector; this is a trickier one. Injectors can fail intermittently or completely, and it's very difficult to diagnose. I've seen failing injectors cause only slight misfire conditions to occur at high engine speeds/loads, and I've also seen them stick completely shut (shutting one cylinder down completely) and fail open (hydrolocking the engine). Injector failure is a very, very common problem that many do not talk about, and is often misdiagnosed by dealers as spark plug/coil problems first. Ignoring a failing injector can result in many other problems, like the ones below.

Valve lash; some engines have a tendency to tighten up valve lash as time goes on (the valve actually sinks deeper into the head from wear on the valve seat). This leads to eventual loss of compression as the valve stays open slightly all the time. This gets worse as the temperature of the engine rises.

Head gasket; now that the L15 is a few years old, and people have used and abused them for thousands and thousands of miles, I've seen some head gasket leaks on stock cars, lightly modified cars, and heavier modified cars. It seems more prevalent in cars that have been run hot in the past, and/or load the car down hard when making a ton of low end torque (something many stock turbo ethanol users seem to like to do). The surface finish on the L15 blocks/heads is pretty laughably poor, and the head bolts fatigue, allowing combustion gas to be expelled into the cooling system. This creates an irrigation path for coolant and combustion gas back and forth.

When cold, coolant will run through that path and puddle in the bore, where it will be burnt off on startup, and the car will sound like a Subaru on cold startup for a few seconds until the coolant is burnt (which you can see significant misfire counts occur at this time). This will be accompanied, of course, with coolant consumption. If left unchecked, this will get worse and worse, potentially damaging other components. The fix for this is, of course, gasket replacement (new OEM Honda), resurface the cylinder head to a much finer surface roughness quality by a good machinist, and using ARP 271-4701 head studs (yes, the ones listed for a GSXR 1300).

Ringland failure; this is by far the least common failure on the L15. The piston's second ring expands from heat to the point of butting the ends of the ring together, deforming it and putting upward or downward pressure on the ringland that carries it. This will be accompanied by compression loss, of course, and require replacement of the piston.

The purpose of this post is not to scare anyone, but rather to inform everyone of the possible causes of misfire codes/conditions."

 

[JayOoz]

Thank

Here's some detailed info on diagnosing those misfire codes from D-Rob himself.

"Misfires and You - a.k.a. How to diagnose your P0300 (301, 302, 303, 304) codes.

Plugs, coils, injectors, valve lash, head gasket, ringland. Those, in that order, are the most probable causes of misfire conditions on L15 engines.

Plugs are pretty self explanatory; I've seen fouled plugs, broken porcelain (where it will be broken and slide up and down the electrode when shaken), etc. If the misfires occur only under high load at elevated boost pressure or in colder weather, the default spark plug gap may be too wide. In that instance, reducing the plug gap down to 0.020-0.025" will solve the problem.

Coils; self explanatory here again. Coils fail and you can diagnose this by moving the coil to another cylinder to see if it moves with it.

Injector; this is a trickier one. Injectors can fail intermittently or completely, and it's very difficult to diagnose. I've seen failing injectors cause only slight misfire conditions to occur at high engine speeds/loads, and I've also seen them stick completely shut (shutting one cylinder down completely) and fail open (hydrolocking the engine). Injector failure is a very, very common problem that many do not talk about, and is often misdiagnosed by dealers as spark plug/coil problems first. Ignoring a failing injector can result in many other problems, like the ones below.

Valve lash; some engines have a tendency to tighten up valve lash as time goes on (the valve actually sinks deeper into the head from wear on the valve seat). This leads to eventual loss of compression as the valve stays open slightly all the time. This gets worse as the temperature of the engine rises.

Head gasket; now that the L15 is a few years old, and people have used and abused them for thousands and thousands of miles, I've seen some head gasket leaks on stock cars, lightly modified cars, and heavier modified cars. It seems more prevalent in cars that have been run hot in the past, and/or load the car down hard when making a ton of low end torque (something many stock turbo ethanol users seem to like to do). The surface finish on the L15 blocks/heads is pretty laughably poor, and the head bolts fatigue, allowing combustion gas to be expelled into the cooling system. This creates an irrigation path for coolant and combustion gas back and forth.

When cold, coolant will run through that path and puddle in the bore, where it will be burnt off on startup, and the car will sound like a Subaru on cold startup for a few seconds until the coolant is burnt (which you can see significant misfire counts occur at this time). This will be accompanied, of course, with coolant consumption. If left unchecked, this will get worse and worse, potentially damaging other components. The fix for this is, of course, gasket replacement (new OEM Honda), resurface the cylinder head to a much finer surface roughness quality by a good machinist, and using ARP 271-4701 head studs (yes, the ones listed for a GSXR 1300).

Ringland failure; this is by far the least common failure on the L15. The piston's second ring expands from heat to the point of butting the ends of the ring together, deforming it and putting upward or downward pressure on the ringland that carries it. This will be accompanied by compression loss, of course, and require replacement of the piston.

The purpose of this post is not to scare anyone, but rather to inform everyone of the possible causes of misfire codes/conditions."

Thank you, Yes i replace the spark plugs and did the ignition coil test and its not the problem either. so its best to take it to the shop as i think is still in warranty.

 

[JayOoz]

Update: at first they tested Fuel injector failed, they reset it and code P0303 is up. Next did an air compression test and there was a major leak.. Honda called for a tear down. They found a blown head gasket. Thankfully Honda care covers it. Hopefully, that will solve the problem for code P0303.

 

[JayOoz]

Another update: honda replace head gasket still show the code. The technician contected the honda tech line advised that it needed a new short block replaced die to bad piston ring.

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