misfire code P0172 and all 6 cylinders misfire

[honda2004]

I need help and suggestion me what I need to check in order to fix the engine codes.

Topic

[BigC]

Hi honda2004,

The P0172 code indicates a rich mixture on Bank 1. So there is not enough oxygen for the amount of fuel being burned, and thus little-to-no oxygen left over after combustion. And all cylinders appear to be mis-firing. A dirty MAF sensor could cause this. I would also look to see if the ECT (engine coolant temperature) sensor is connected and working properly. A scan tool with a live-data function would help here. Also, too much fuel pressure (bad regulator) at the rail could create this condition. Confirming the proper fuel pressure would also help.

Also ensure that the air filter is not clogged. Good luck and keep us posted.

[Grayfox]

P0172 Honda Fuel System Too Rich
P0300 Honda Random Misfire
P0301 Honda No. 1 Cylinder Misfire
P0302 Honda No. 2 Cylinder Misfire
P0303 Honda No. 3 Cylinder Misfire
P0304 Honda No. 4 Cylinder Misfire
P0305 Honda No. 5 Cylinder Misfire
P0306 Honda No. 6 Cylinder Misfire

I would suggest checking spark plugs to see if they are foaled, Air filter, Spark plug cables and O2 sensor.

Something is causing the system to run rich.

[honda2004]

today, I checked the air filter. yes, it was dirty. I went to Autozon part, I bought STP air fiter and replaced. still feel the engine rough …

Do you think all 6 spark plugs bad? the spark plugs changed when at 100,000 miles. now the car has 138,000 miles. I wish I have scan tool that capture live shot.

do you have suggestions what I need to check? could this somethiing I can fix or profession machanic has scan tool to capture this type of job? don’t want throw parts and not fix my problem (shop machanic).

please help me… tomorrow, I check the condition spark plugs.

what you think? coil packs be the problem ? if P0172 code, why that contribute to misfire all 6 cylinders?

[johnzcarz]

If the mixture is too rich it may be causing a misfire, just as when it’s too lean. You have 2 clues – misfires on ALL cylinders and the car is telling you there is a rich condition. I’d be looking at anything that could be causing the ‘dumping’ of fuel – like measuring the fuel pressure to see if it’s the fuel pressure regulator, another possibility is the ECT (as BigC said), and I’d look at the primary oxygen sensor output too.

I’ve seen some run so rich the cat was glowing – dumping fuel is not good for them.

[Grayfox]

I would pull the negative battery cable off and let the ECU reset so all the codes clear. and see if it gives another Check engine light.

[dreamer2355]

Having a scan tool that shows live PID data would be very handy or your just going to be playing a guessing game.

First off, did you use OEM replacement plugs for that vehicle?

According to the CEL trouble codes, only bank 1 is running ‘Rich’, not both as you have a V6.

I would first check fuel pressure with KOEO specifications and KOER and compare those against factory readings. I would also do a injector leak down test.

You can loan fuel pressure testers from most reputable auto parts stores.

If the fuel pressure regulator on your vehicle vacuum operated or do you have a return-less fuel system?

[honda2004]

Today, I did reset ECU. Two minutes later, the engine light come back. use the fuel pressure testers, what is the good place to plug the fuel pressure tester? install fuel pressure tester on fuel filter is a good spot to check?

does someone know what factory reading spec fore fuel pressure reading should be? the car crank fine and run fine, but feels shaking with engine light codes
P0172, P0300, P0301, P0302, P0303, P0304, P0305, and P0306.

the Acura car should be top car, can the fuel pressure regulator goes bad that early?

can someone provide Diy how to test fuel pressure regulator with fuel pressure tester?

[honda2004]

I have not done this before… someone has good link show how to test fuel pressure regulator? hope Eric has a video how to test fuel pressure regulator? hope someone guide me to the right link.

[dreamer2355]

The best way of testing coil packs is to stress test them usually under load. You can buy ignition testers from most auto parts stores.

And yes, the NGK plugs will be fine.

[johnzcarz]

If the numbers match then you are OK – you don’t have to buy them from the dealer unless you want to pay 2-3 times more.

[EricTheCarGuy]

I would table the fuel pressure thing for now as it’s not common for that car to have a problem with that or any Honda for that matter. The first step should be to do a power balance test to see if you can nail down the effected cylinder(s) as it may be something as simple as a bad coil pack. I know you have multiple codes but to be honest the system is not very good at picking out a single cylinder misfire. The ‘system too rich’ code may be a symptom of a coil pack that isn’t firing properly as it won’t burn the fuel in that cylinder and send it straight to the O2 where it will read rich.

Here is a video on how to power balance that engine. Also use NGK or Nippon Denso plugs only, they cost more but if you use anything else on that engine it is likely to cause problems. The upside is that if you use the correct plugs you only have to replace them every 100K

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

[honda2004]

Thank You, Eric…. I think I bought all 6 spark plugs from Napa Auto Parts with NGK (match part # written on the spark plugs itself). is that OK or go with OEM spark plugs? sometimes, the part # match on spark plugs aftermarket… is that a way to check or valid to put in the car w/o use OEM parts? Eric, hope you can comments on this…

Tomorrow, I will stop at the Acura Dealership get all 6 sparks plugs new and replace all them. Also, I do have 3 spare coil packs to test out.

What I need to check when I replace a new coil packs? can coil pack check not under load to see the coil pack went pack.. or the coil packs have to be under load.. If I remember from Eric, you can’t check resistance on the coil pack because coil packs need to be under load.

Hope Eric can share or someone can share how to test the coil pack when remove all out the car.

Thank you Eric and to all that give feedbacks… Yes, I will update this week if I went ahead replace all OEM spark plugs to see check engine light goes out.

Is there a way to check coil pack to see if it’s bad with a meter?

[Grayfox]

If the manual says use NGK-XXXXX i would say it is fine, i did it for my older car and i had no ill effects.

[honda2004]

Updates…. Today, I took a spare coil pack.(GOOD OEM coil pack) and swap out each cylinder at a time. I have to say, by doing unplug the coil pack at a time. Sometimes hard to tell the different under power balance test. it perhaps took longer by swap out each cylinder at a time, but I can tell the different.

Report back… Coil pack # 2 and #3 cylinder are bad. replaced with a spare (Qty. 2 OEM coil packs) that I bought while back. took a drive test 20 miles in highway, the engine came back but this time the code is still pending P0172 (Fuel system too rich bank 1).

Have a question? Can someone tell me where is bank 1 spark plug if I stand in front of the engine?

Oh, I kept all old spark plugs while swap each coil pack out. the old spark plugs are still on the engine.

Now, what can be wrong with P0172 code? Can the spark plug went bad not burn gas?

the previous code P0300, P0301, P0302, P0303, P0304, P0305, P0306 and P0172. I have to report, all cylinder misfire went away but still has check engine light with P0172.

Look back my old file, I found old box spark plugs that I bought from Napa. It says outside the box is NGK spark plugs and LASER IRIDIUM PREMIUM.

Is OK to use that spark plugs? Right now, those old spark plugs are still on my Acura 2004 TL.

Eric or someone can give me suggestion to check next. I am thinking the spark plug on Bank 1 might be bad? Need suggestions what to do next..

[BigC]

Glad to hear you found a bad coil. Did you clear all the codes before driving the vehicle again? For the 3.2 engine, the cylinder numbers are as follows:

Standing in front and looking at the engine, the cylinders closest to the radiator side are #4, #5, and #6 from passenger side to driver side. The cylinders closest to the firewall are #1, #2, and #3 from passenger side to driver side.

If the code P0172 still occurs, take a look at the live data for the upstream O2 sensor. I believe this vehicle only has one upstream O2 sensor. The O2 sensor could be bad, especially if this is the original O2 sensor with 136,000 miles on it. Good luck and keep us posted.

[Author]

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