my99ekcoupe

Hey i have a d16y8, P2P ecu, with a CEL, i checked the code and its 45 Fuel system too rich or lean.
So far i've replaced fuel filter,
ran fuel injector cleaner through twice!
seafoamed the car..
If it helps, everytime i reset the ecu it takes anywhere from 30min to 4 hours to pop back up!

Oh and also, the head was replaced to a newer one, and same problem..

Anyone know what it could be?

Duane_in_Japan

The first thing you have to do is check the voltage from the MAP sensor going back the the computer at a fully warmed up idle with no accessories on. It needs to be just a hair under 1 volt DC. Anything else, you need to do a valve adjustment, use a digital meter to test.

my99ekcoupe

I'll go to autozone tomorrow and get it checked. But what does the voltage of the MAP sensor give me? And what would be the need for valve adjustment? i mentioned this is a newer y8 head and it still has the same code as the old head i had. I dont think its the valve's.

Duane_in_Japan

The amount of air (vacuum) that the engine pulls in is directly proportional to the voltage that the MAP sensor feeds back to the computer which is dictated by how much the valves open to allow X amount of air into the cylinders. Lower vacuum makes the computer think that you are giving more throttle and the computer delivers more fuel to the mixture thus making the emissions rich. If one fuel injector is not producing, this too will produce less vacuum and show the O2 sensor more oxygen and the computer will deliver more fuel to the other three cylinders but may overall still show lean emissions, but in this case an incorrect MAP reading will not be a valve adjustment.

You are correct, it could be several different possibilities, but this is your starting point since you dont have your own scanner or multimeter to check readings yourself. The MAP sensor may have the highest authority on the air/fuel mixture ratio, the O2 sensor will also be a high authority so these two sensors will be the front line of defense but you need to know how to read what they are telling you.

IF, both heads have the same problem, MAYBE it is due to both heads being misadjusted by the same person???

my99ekcoupe

no i actually think i did a good job adjusting these valve's
Oh, but i did end up keeping my old fuel rail and injectors. Is there a possiblity it's a bad injector?

my99ekcoupe

Anyone have any ideas?

honda fossil

yes your injector could be leaking but aslo check the exhaust manifold they like to crack around the o2 sensor giving false reading also check your fuel trim both short and long term to find out if going rich or lean

my99ekcoupe

Exhaust manifold looks good, fuel injectors dont seem like they're leaking or anything And how do you check the fuel trim?

Former User

Start by pulling the OBDII code with a scan tool. This code will tell you whether you have a too lean or too rich problem.

my99ekcoupe

it's too lean

Former User

Does the engine have any performance problems? How do the spark plugs look?

Check for any possible sources of an exhaust leak upstream of or near the primary O2 sensor.

Measure the fuel pressure.

honda fossil

so if your fuel trim is showing lean your car is running rich and you most likly have a leaking injector to find out simply remove the 10mm cap screw on the fuel rail and hook up a pressure tester . next turn the key to on and as the fuel pump prim the sys the pressure should hold if not next pinch of the fuel retrun (just for good sake) if pressure still drop after priming you just proved you have a leakie injector

my99ekcoupe

Car run's great, no performance problems at all, spark plugs were just replaced a month ago.
I think i might have a small exhaust leak because i am missing the gasket between the header & down pipe, if the stock header should have one.. Could that be it?

Former User

Yes. Install an exhaust gasket. The lack of performance problem fits with an exhaust leak, especially if you have also noticed lower gas mileage.

my99ekcoupe

Alright, i was planning on installing an aftermarket header anyway so will do it in about a week.

Also one of the fuel injectors rings are a tiny bit torn but doesn't seem to be leaking..

Former User

Replacing the O-ring would also be a good idea, just to rule it out.

my99ekcoupe

Alright will do. I'll keep you guys updated on my progress.