MDX Engine on my 2004 Pilot

[pilot_cruiser]

Allow me to introduce myself..and share my pilot ownership to this point..

I purchased a 2004 Honda pilot EX back in 2008 with only 39K miles. It was a replacement car for my mother. and was used to drive the kids to and from school and do groceries. etc..

Fast forward to December 25 2010.. we decided to drive from Toronto to Florida along the east coast and back with 7 passengers and a trunk full of luggage.
We has just done an oil change and the car was ready to go
10 days and 5000 miles later we're back in detroit on the last leg of our journey and it's freezing cold outside. I turn on the car and notice it sounds like diesel tractor. I check the oil and nothing!.. so I let it warm up and re-check after 15 minutes.. slowly the reading starts to show on the dipstick..

We take it to a dealership in Toronto to diagnose the issue and correlate with my own research. Dealership confirms it's "piston slap". Further investigation by independent shop reveals that oil had turned to sludge which must have caused overheating of the pistons and deforming of the O-rings leading to the piston slap on cold starts..what's worse.. the car never once indicated that it was low on oil pressure which was very disturbing.

Fast forward to Decemeber 2011.. with 84K miles.. the car snaps the timing belt, at which point we decide to put a new engine on the car.

mechanic finds us a japanese import 2004 MDX engine with only 54K miles and we put a new timing belt,water pump, tensioner and have it installed.

Just brought it home today and noticed a check engine light + hard brake pedal feel.

we're taking it back tomorrow to have it diagnosed
has anyone heard of a similar engine swap done on these vehicles? shouldn't the ECU also be swapped with the Acura ECU if we're swapping engines? I've read threads here noting slight differences between the two engines but curious to hear any input.

also.. has anyone experience this oil sludge issue on the pilot? we went through some very extreme weather in the the 10 day trek.. not sure if that has any effect.

Thanks in advance!

[iggibar]

The ECU should've been remapped for a new different engine. The only exception is if both ECU's were set exactly the same from both cars. ECU's don't have to be swapped, just reprogramed.

[megatron]

Regarding the sludge issue, did you check the oil level right after the oil change? It would seem WAY more likely that they underfilled your oil than anything else. This is exactly why I gave up letting others change my oil and do it myself now instead.

I mean unless they used like straight 40 wt or higher oil, there is no way that it can get cold enough to sludge up your oil to the point that it's not registering on your dipstick until its warmed up!!! That totally sounds like an underfill problem. I mean 5w-30 oil flows down to like -30 something Fahrenheit and I don't think you were that low in Chicago! Think about places like Nome Alaska where it is routinely in the -20s and -30s!!!

The low oil pressure indicator only lights when there is essentially no oil in the engine. It's not meant to be a low oil indicator. It sounds like you had some oil in there because you said it registers on dipstick when warm. Running 5000 miles with low oil will definitely cause the engine problems you had.

I guess moral of the story is to personally check your oil level before going on a long trip EVEN if you just had your oil changed! And it prob doesn't hurt to check along the trip too!

[xGS]

Originally Posted by megatron

I guess moral of the story is to personally check your oil level before going on a long trip EVEN if you just had your oil changed! And it prob doesn't hurt to check along the trip too!

Does anyone actually follow the "Owner’s Maintenance Checks" section of the owner's manual, which says to check the engine oil level every time you (re)fill the fuel tank?

[dball711]

I check mine every other fill up...

[rocky]

Have to admit the Pilot was the first car I ever bought without looking under the hood. I check the oil level after every oil change to make sure it's at the correct level. Otherwise it's only checked when I fill the windshield washer. Still no noticeable oil consumption after 130k.


Sent from my Autoguide iPhone app

[94eg!]

Yes, if they cannot reprogram the ECU, then it should have been swapped out. They are both 3.5L blocks, but the MDX makes 25 more horsepower. That means there are definitely some differences. You can bet a few of those ponies come from the exhaust & intake on the MDX, so I would say about 15-20 hp difference in the motor itself.

Now the engine management in the more modern Honda's are pretty advanced, so a stock ECU may be able to compensate. They use wideband O2 sensors which are capable of detecting excess intake flow.

BTW: Typically Acura motors have higher compression than Honda engines. That means your gonna need to feed the motor premium fuel to get the most out of the engine. When the ECU detects knocking (from lower grade gas + high compression), it retards your ignition timing and results in lower performance and wasted money. If a Honda calls for 91 octane, you better use it.

It also means that the ignition maps in the Pilot ECU will NOT be optimized for an MDX engine. This may be the root of your problem.

I just looked it up, 04 MDX and 04 Pilot both run 10:1 compression. I would think it would be fine to run the Pilot ECU and 87 octane.

[pilot_cruiser]

Thanks for all your responses
my father always watches over any mechanic that works on the car. and he assured me he was there and he even bought the engine oil himself the day before we took it on our trip so i'm confident the oil change was done right..

but in any case.. how does a low oil translate to oil sludge?
When I say oil sludge i actually mean there was gunk all over the dipstick, and they fished out sludge from the drain hole when they took it to the mechanic afterwards. If i remember correctly they dropped the oil pan several months afterwards and cleaned out all the sludge from underneath.. but it was never the same.. since that point we did a lot of engine treatment and put heavier oil to prevent the knocking. I believe this is what ended up causing premature timing belt failure.

as for the ECU.. i've read about the differences in HP b/w MDX and pilot stemming from subtle intake and exhaust manifold differences. Threads on this forum conclusively indicate that 87 octane on an MDX is OK and has no effect on ignition timing except under WOT.

we suspect it was bad oil to begin with. Although we went from freezing temperatures in the northeast to sunny and warm in miami over the span of a few days. I checked the oil once in florida and it was ok.
I put a quart of oil in detroit before driving it home

[megatron]

Originally Posted by pilot_cruiser

Thanks for all your responses
my father always watches over any mechanic that works on the car. and he assured me he was there and he even bought the engine oil himself the day before we took it on our trip so i'm confident the oil change was done right..

but in any case.. how does a low oil translate to oil sludge?
When I say oil sludge i actually mean there was gunk all over the dipstick, and they fished out sludge from the drain hole when they took it to the mechanic afterwards. If i remember correctly they dropped the oil pan several months afterwards and cleaned out all the sludge from underneath.. but it was never the same.. since that point we did a lot of engine treatment and put heavier oil to prevent the knocking. I believe this is what ended up causing premature timing belt failure.

we suspect it was bad oil to begin with. Although we went from freezing temperatures in the northeast to sunny and warm in miami over the span of a few days. I checked the oil once in florida and it was ok.
I put a quart of oil in detroit before driving it home

If you definitely checked the oil in Florida and the level was normal, then it must have somehow leaked or burned away on your drive back. Maybe you were very unlucky and something hit your oil filter hard enough to cause it to leak? Or did you create any enemies on your trip that would have reason to drain your oil on purpose while you were sleeping?

I doubt you would have developed an internal leak big enough to burn away that much oil in such a short time.

To answer your question about how low oil translates to oil sludge... it's very simple. Low oil means less medium to transfer heat from the engine to the coolant. That means the oil stays at a higher temperature. The lower the oil, the higher the temperature... so what you end up doing is burning and evaporating the oil. Burned and evaporated oil leaves sludge.

There is no doubt in my mind that the low oil level caused your engine damage and sludge. That leaves the question of how your oil got so low. It's either the initial oil change or somehow you lost oil somewhere along your drive.

Oh and in regard to "bad oil", no matter how generic or cheap the oil was, it shouldn't leave sludge and disappear over one 5000 mile drive!

[pilot_cruiser]

So the problem with the low oil correlates well to the fact that when changing out the engines.. we opened the oil pan on both cars to swap oil pans since the MDX one was dented ( during removal ).. and noticed a lot of burnt oil stuck to the oil pan of the pilot which required heavy acids to remove.

I have not driven the car since we got it back but i'm told now that the check engine light and VTM-4 light is on and the car has trouble accelerating. i.e you really have to push all the way down on the pedal to get the RPMs up. do these cars go into "Limp mode" when they throw a CEL light? or could this be related to some other reason?

[megatron]

Originally Posted by pilot_cruiser

So the problem with the low oil correlates well to the fact that when changing out the engines.. we opened the oil pan on both cars to swap oil pans since the MDX one was dented ( during removal ).. and noticed a lot of burnt oil stuck to the oil pan of the pilot which required heavy acids to remove.

I have not driven the car since we got it back but i'm told now that the check engine light and VTM-4 light is on and the car has trouble accelerating. i.e you really have to push all the way down on the pedal to get the RPMs up. do these cars go into "Limp mode" when they throw a CEL light? or could this be related to some other reason?

Did you read the codes causing the CEL? That should give you a clue. The Honda engines don't usually go into a limp mode as far as I know... but maybe if it's bad enough, it will. I would suspect this has something to do with swapping in an MDX motor without changing or reprogramming the ECU, but that's just a guess. As was said in some previous posts, although they are the same displacement and resemble each other, there are differences, so the ECU is probably not matching with the motor. You should have the place who swapped motors for you take care of this...

[N_Jay]

I am betting something small was missed during installation.

Make sure all the sensors are hooked up.

If you have the old Pilot sensors, I would think about trying them one at a time.

[94eg!]

I had a look and the cams are different between the two motors. I would definitely be reluctant to drive them on an unmodified ECU.

And yes Honda's DO go into lip mode if something is VERY wrong. Usually you will see a ~3.5k rpm rev limiter in limp mode.

[pilot_cruiser]

we're planning to take it to the mechanic tomorrow to look at the CEL issue but it turns out the accelerator problem ( i.e. LIMP MODE) was actually due to the throttle wires not sitting properly on the pulley guides.. so that problem has been resolved. The only remaining issue is the CEL and VTM-4 light..

when the timing belt went on the original engine, these lights came on. I assume you can't just clear the codes on this car by disconnecting the battery can you?

[pilot_cruiser]

Originally Posted by 94eg!

I had a look and the cams are different between the two motors. I would definitely be reluctant to drive them on an unmodified ECU.

And yes Honda's DO go into lip mode if something is VERY wrong. Usually you will see a ~3.5k rpm rev limiter in limp mode.

From what i understand, the timing belt, and tensioner is the same on the MDX and Pilot, so the timing must be the same no? relatively speaking. Good thing the motor is under warranty for a few months.. I can't see how the ignition profile differences would cause catastrophic damage. doesn't the ECU "learn" the optimal timing as you drive the car?