[TXP]

This post doesn’t have to do with my wife’s Pilot, but hear me out. Since there are relatively few V6 Accords, I was hoping a community more familiar with the 3.5L V6 engines might have a better chance of solving this mystery. This site seems to have more V6 knowledge than most Honda related forums. Mods, I'd understand if you deleted this post for not being Pilot related.

At a high level, this is the issue my 44,000 mile, 2016 Honda Accord EX-L V6 is having. Intermittent long cranking time when the engine is warm’ish. The normal cranking time is 1 - 1.5 second duration. When it does exhibit the issue, the cranking time is about 4 - 5 seconds. The issue is getting worse and happens on a weekly basis now, when it has been sitting just along enough to cool to that slightly warm temp.

• Occurs when the engine temperature gauge reads just right in the middle between normal operating temperature and the cold mark. This seems to be a key point. Granted this may be a narrow temperature range because the temperature gauge is one step above an ‘idiot light’.
• Normal (full) operating temperature starting is just fine.
• Cold (ambient temp) start temperature starting is just fine.
• 10k miles ago it used to have what seems like a slight cylinder misfire once in a long time for a few seconds after turning over when cold. Haven’t noticed this misfire for thousands of miles and no code was ever logged.
• The battery was replaced by the dealer just under 2 years ago.
• The starter cranks the engine as fast as it ever has, so no starter performance degradation.
• TBS performed for fuel system reprogramming probably over 2 years ago. No engine stalling or loss of power had happened, so the dealer didn’t replace the fuel pump, per TSB instruction.
• I run either Quik Trip, Costco or HEB gasoline. QT and Costco are “Top Tier”, for what that’s worth.
• Been running VCM Tuner II to disable the VCM for about the last 7K miles. However, for the last 2 months, I’ve had the unit turned off. The way the unit is designed to work, it shouldn’t affect what the engine computer reads except right at the point the engine reaches full, normal operating temperature. Otherwise it sends the real temperature reading to the computer.
• I can sometimes notice a stronger exhaust smell right after a long cranking event. Then again, the car has always seemed to have a slightly stronger exhaust smell upon startup for about 15 seconds. I don’t go around sniffing the exhaust, but it has never failed to Pass annual emissions testing.

From the internet, I’ve compiled a short list of possibilities and my thoughts on them.

• EGR system. Unless the engine is running out of spec, the EGR passages in the intake shouldn’t be clogged by this point (44K miles). The EGR likewise shouldn’t be failing this soon.
• Battery ground (-) terminal. The battery is grounded to the front top crossmember. As finicky as electrical systems are in modern cars, all sorts of strange things can happen if electrons cannot flow just so. The connections seem fine, but I’ll take them off and clean them anyway. People suggest running an additional ground wire onto the engine.
• Leaking fuel injector. From what I’ve read, this can cause a loss of fuel system pressure after the engine shuts down and potential rich F/A reading (when starting).
  • The loss of fuel pressure could potentially cause a delay in the engine firing over while the fuel system re-pressurize. If this was the case wouldn’t I also see long cranking time when the engine is cold?
  • As for a really rich F/A mixture sitting in the intake manifold or in one cylinder, I’m not 100% sure how that could affect the ability to start. I don’t think the engine could detect the condition and not fire the spark plugs since all the sensors are up wind of the intake manifold. Maybe the F/A mixture is too rich for the ignition of the fuel? Since I don’t think this is a “direct injection” engine, I supposed that the rich F/A mixture could flood the entire intake manifold and result in super rich F/A in all cylinders, thus preventing combustion for 4 seconds while super rich mixture is cycled out of the cylinders.
• Check valve failure in the fuel pump. Like the leaking fuel injector, this could result in a low pressure scenario that takes a few seconds to build back up before the engine gets the necessary fuel squirting into the engine. Again, wouldn’t this happen also on cold starts, not just warm’ish starts?

I’d rather not take the car into the dealer before I make a respectable attempt to avoid a 4-digit repair bill. Dealers are good at installing new parts, but not always the best at diagnosing. I’d also rather not prematurely wear out my starter since they can be expensive and not something I think I’d enjoy replacing myself on this car.

If women cannot find you handsome they should at least find you handy. Therefore, I’ve become respectively handy under the hood. I’m willing and able to try some repairs, but I need wiser minds to help me find a starting point and prioritize my work.

 

[Nail Grease]

I doubt they will delete your post. They might move this to other vehicles.
Thanks for having some trust in us. I speak for myself, I'll do all I possibly can to prevent sending my vehicle to a shop.
Have you ever cleaned the MAF?

 

[Nail Grease]

I doubt they will delete your post. They might move this to other vehicles.
Thanks for having some trust in us. I speak for myself, I'll do all I possibly can to prevent sending my vehicle to a shop.
Have you ever cleaned the MAF?

I ask about the MAF because we had a post not to far in the distant past where a butterfly wing was lodged in MAF causing the air/fuel be badly off. I uses CRC Electronic Cleaner or MAF Cleaner. Remove the sensor and spray a few short bursts directly into the visible electrodes. Let dry thoroughly before re-installing. I'd also inspect the opening of the throttle body for debris. Inspect Air filter, filter box and intake tube clamps should be tight, no air leaks. If you have an OBD II scanner, What is the MAF reading? Maybe post a photo of your long and short term fuel trims.

 

[TXP]

I hate leaving questions unanswered, so I'll give an update.

I checked, tinkered with and cleaned several things on the engine. Ran some wicked strong fuel treatment through it. The fuel treatment helped, some, I think. Still, nothing really solved the longer cranking times.

In the end I removed the "VCM Tuner II". Within 1000 miles the starting issue disappeared completely and not one long crank time since. My theory is that over time the VCM tuner threw the engine settings off to the point that the engine had some issue starting normally in that specific window of engine temperatures.

The other thing I observed was that the MM for the oil changes went much longer than previously by about an additional 4K to 5K miles. I figure this is due to the way the VCM tuner works. It reads the engine coolant temp and forwards that to the computer until it reaches a certain temp, then after that it sends a programmed temperature reading to the computer that is just below where the computer would allow the regular cylinder deactivation to be enabled. The fail safe is if the engine temp gets too high, it would then send the actual temp so as to hopefully not cook the engine. Since the MM never saw normal or elevated temps, I guess it figured the oil was not going to need to be changed as soon.

The "VCM Tuner II" didn't work out, so if anyone wants one, I got one for sale.

 

[rl911]

How could the VCM tuner have anything to do with starting? Also don’t understand why it would change oil change intervals. Hasn’t done that on both my 16 and 19 pilots, both go about 7500 miles or a year before getting close to 0%.

 

[Nail Grease]

I hate leaving questions unanswered, so I'll give an update.

I checked, tinkered with and cleaned several things on the engine. Ran some wicked strong fuel treatment through it. The fuel treatment helped, some, I think. Still, nothing really solved the longer cranking times.

In the end I removed the "VCM Tuner II". Within 1000 miles the starting issue disappeared completely and not one long crank time since. My theory is that over time the VCM tuner threw the engine settings off to the point that the engine had some issue starting normally in that specific window of engine temperatures.

The other thing I observed was that the MM for the oil changes went much longer than previously by about an additional 4K to 5K miles. I figure this is due to the way the VCM tuner works. It reads the engine coolant temp and forwards that to the computer until it reaches a certain temp, then after that it sends a programmed temperature reading to the computer that is just below where the computer would allow the regular cylinder deactivation to be enabled. The fail safe is if the engine temp gets too high, it would then send the actual temp so as to hopefully not cook the engine. Since the MM never saw normal or elevated temps, I guess it figured the oil was not going to need to be changed as soon.

The "VCM Tuner II" didn't work out, so if anyone wants one, I got one for sale.

How could the VCM tuner have anything to do with starting? Also don’t understand why it would change oil change intervals. Hasn’t done that on both my 16 and 19 pilots, both go about 7500 miles or a year before getting close to 0%.

I think I may need to wait until the morning after a cup a coffee to try and wrap my head around this one.
🤔

 

[Slvr7]

How could the VCM tuner have anything to do with starting? Also don’t understand why it would change oil change intervals.

It effects starting because coolant temp is a very important input to the fuel/ignition strategy. It would seem as though the tuner was defective and skewing the coolant temp the ecu was seeing. Oci was effected because temp is one of the calculations used in the algorithm.

 

[dp0099]

What about the oil change interval? If the tuner is working properly and caps ECT1 at ~163F, would that affect the oil change interval?

 

[TXP]

What about the oil change interval? If the tuner is working properly and caps ECT1 at ~163F, would that affect the oil change interval?

I don't know specifically about Honda's algorithm, but the maintenance minders (MM) in many brands takes multiple factors into account when calculating when items need service. Temperature (engine, environment), run time, frequency, etc. With the VCM Tuner II feeding in lower than full operating coolant temperature to the car's computer, I'm guessing that the computer thinks the oil hasn't been subject to as high operating temperature and therefore isn't being 'worn out' as fast.