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thebesthonda, ASE MasterTechnician
Category: Acura
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Experience:  26 years experience
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2005 Acura MDX 3.5L Service engine is coming on when coming

Customer Question

2005 Acura MDX 3.5L Service engine is coming on when coming to a complete stop. I put a code tester on car. It is shown misfire on 1,3,4,5,and 6 cylinders with a random misfire also. I change all spark plugs and one ignition coil. The same problem is happen. It run worst with a/c on. Any idea of what this cause be?
Submitted: 10 months ago.
Category: Acura
Expert:  david craig replied 10 months ago.

hi im david , thanks for visiting the site. do you have any other codes other than P0300,301,303,304,305 and 306?

Customer: replied 10 months ago.
that is all the codes.
Customer: replied 10 months ago.
sorry, random misfire
Expert:  david craig replied 10 months ago.

wow. if you take the new ignition coil and move it around to another cylinder does the misfire for that cylinder go away?

Customer: replied 10 months ago.
David Craig, you still there?
Expert:  david craig replied 10 months ago.

yep

Customer: replied 10 months ago.
code tester said 4 and 6 cylinder with random misfire. I put on a new coil 4cyl. I take 6 coil and put on 3cyl. 3coil on 6cyl. still missing.
Customer: replied 10 months ago.
I'm still getting same code on tester.
Customer: replied 10 months ago.
David, any idea?
Expert:  david craig replied 10 months ago.

so the misifres on on 4 and 6 still?

Expert:  david craig replied 10 months ago.

put a noid light on the injectors for the misfiring cylinders.

Customer: replied 10 months ago.
what is a noid light?
Expert:  david craig replied 10 months ago.

its a small light that plugs into the connector for the fuel injectors. when you crank the engine its flashes to let you know you are getting a pulse command from the computer to fire the injector

Expert:  david craig replied 10 months ago.

if you have no pulse. you get a misfire

Expert:  david craig replied 10 months ago.

harbor freight sells a good set for cheap

Customer: replied 10 months ago.
it may be a probable injector?
Expert:  david craig replied 10 months ago.

if its not a coil or plug, it will be an injector or the wiring to the injector or the computer.

Expert:  david craig replied 10 months ago.

probably not the computer though

Customer: replied 10 months ago.
should I try the new coil on each cylinder?
Expert:  david craig replied 10 months ago.

do you have a known good coil?

Customer: replied 10 months ago.
i just purchase it. new.
Expert:  david craig replied 10 months ago.

put it on one of the misfiring cylinders and see if that cylinders misfire goes away

Customer: replied 10 months ago.
How much is a computer for this Acura?
Expert:  david craig replied 10 months ago.

its alot. but dont worry about the computer. lets concentrate on the misfires.

Customer: replied 10 months ago.
I try new ignition coil on each cylinder, still missing each time I changed it.
Customer: replied 10 months ago.
I will try noid light tomorrow. any more idea you may have before i let you go David.
Expert:  david craig replied 10 months ago.

no more ideas until we know that all the injectors are firing... ill be on tomorrow.

Customer: replied 10 months ago.
David, I just finish,all injectors are firing. noid light was lighting up on the cylinder.
Expert:  david craig replied 10 months ago.

ok, now you need to do a fuel pressure test

Customer: replied 10 months ago.
where is port to do fuel pressure test on 2005 acura mdx 3.5l
Customer: replied 10 months ago.
David, you there?
Expert:  david craig replied 10 months ago.

yes

Customer: replied 10 months ago.
where is port to do fuel pressure test on 2005 acura mdx 3.5L
Expert:  david craig replied 10 months ago.

hang on

Expert:  david craig replied 10 months ago.

https://youtu.be/quVBlKP7rdw

there is no schrader valve on the fuel rail. you have to tap into the lines ... this video will show you how

Customer: replied 10 months ago.
I just check injector with a electronic fuel injector quick probe. it looks like all injectors are working.
Customer: replied 10 months ago.
David is this the connector I need to tap into?
Expert:  david craig replied 10 months ago.

for fuel pressure? yes

Expert:  david craig replied 10 months ago.

hows it going?