GroverO

2002 MDX 284,000 miles. I have had the vehicle for 10 years. Scheduled maintenance has always been done.

My son has the vehicle at school in St Louis. Coils replaced in 2013, Valve adjustment done a while back and carbon cleaned from manifold passageway done August 2016.

Early October VTM and CE light went off and it runs poorly, very sluggish under load. Wont run well over 40 mph or so.

Since he is away, my usual shop cant look at it. Codes pulled indicate EGR and misfire. Shop replaced fouled plugs, no luck, still misfires under load and it fouled the new plugs.
Pulled plugs when they first got it, very fouled, ran the car and fouled the new set of plugs.

They then called 2 weeks ago and said it was fixed: 3 valves needed adjusted, 2 ignition coils were bad, EGR valve was also bad. They test drove it and said it was all good.

So $1150 later she seems good to go....according to them.

My son calls 2 days after getting the MDX back, same deal. CE light, runs rough under load. Took it back to the shop a week ago yesterday. Talked to them today, they cant seem to find what is causing the issue? I talked to my regular repair guy who has worked on the vehicle for the past 10 years and he wonders if it could be the computer?

Any thoughts? I hope to get a few more years out of it. My other son turns 16 in December and I want to have the 2002 for a local car and give my 2009 MDX to my St Louis son. I just picked up a 2014 Advance/ENT 2 weeks ago.

Thanks!

Daron

thoiboi

Did they replace with OEM equivalent NGK Iridium plugs and OEM coils? These cars are quite finicky in this department. But the new plugs still being fouled is leading me to believe it's an issue with the fuel delivery system... what are the check engine codes?

GroverO

thoiboi:

I am not sure if they used OEM equivalents.

I dont have the specific code #s. Initially it was bad egr valve and multiple engine misfires.

thoiboi

Ask for both of those, gonna be a problem if they don't use OEM ones and those DTC codes are crucial for determining the problem and solution

GroverO

Stay tuned, sent them an email asking for that info.

Thanks!

thoiboi

no problemo! good luck!

GroverO

Tech says it is a P1799 code.

It idles fine, begins to misfire around 2500-2700 Rpms
ans gets worse as throttle is applied

GroverO

The P1799 looks be a tranny speed sensor code.

Doubt that would cause my issues.

thoiboi

How about those plugs and coils being OEM?

GroverO

Yep, they are OEM.

csmeance

Check fuel pressure and also check fuel injectors as fouled plugs usually indicate the car running rich!

You can try getting an ECU from another car but you'll have an issue with the immobilizer system and may have to get the new/replacement ECU programmed to your MDX. Have a tech check the ECU/ECM for water damage! Sometimes the A/C drain gets plugged up (mold or a shop puts a screw in the drain so it doesn't drip during an oil change, etc) and it backs up and gets the ECM wet.

P1799 can be triggered by fouled spark plugs or a bad IAT sensor (incoming air temp sensor for intake)

GroverO

From another board: Could this be a possibility?

Could a faulty transmission speed sensor cause the engine to go into "limp" mode and limiting rpms? Sensor thinks tranny/rpm too high and computer cuts spark to cause miss and lower rpm?

GroverO

Well, still no luck. Mechanic has been in contact with a mechanic at an Acura dealership closer to me. Had him check the ground straps, still no luck. Fuel pressure is good. Idles fine, starts acting up around 2300 rpms.

I finally stopped by the shop when I picked my son up for thanksgiving break. Been in business since 1920 or so. They want to make it right.

At at what point do we think the computer is shot? What does Acura charge to program it?

any other ideas?

GroverO

Had the MDX shipped home last week to my local shop.
My shop thought it may be the Ecu after all.

Showed a egr code even though the egr valve is new and passageway is clean.

When scanner is plugged in the ecu is not showing real time data nor is it showing the basics (vehicle vin, etc)


Talked to head service guy at closest dealer. He agrees it could be ecm.

Found a ecm locally for 50 bucks, drove to my Acura dealer yesterday. They installed it for about an hours worth of labor. Car ran great on 90 mile drive home.

Fingers crossed! Hopefully it's resolved.