2015RDXTech

I have a 2015 that started misfiring about a month ago. The first time it happened, I was on the highway and the Power Steering, VSA, and Hill Start Assist lights all came on. The Check Engine light started blinking and the car was shaking a lot at low speeds. It threw misfire codes for 3 cylinders, and I had it towed to a dealership. Three days later I got the car back, and I was told they couldn't find anything wrong with the car, and that it was probably just some bad gas. On the highway that same night the car misfired again, so I stopped at a gas station, added some fuel system cleaner, and got back on the road. This seemed to fix it for around 3 weeks until it happened again a few days ago.

Has anyone else had a similar issue?

egads

Missing information: the current miles.
I would be curious if the three misfiring cylinders were the ones that shut down with VCM. This V-6 with variable cylinder management in other Hondas has had some serious
issues with this. Some of them have "low friction" piston rings that Honda is replacing under a settlement. (pretty sure a 2015 RDX doesn't have them) But even outside of that, one might want to check the condition of the spark plugs.
If any are fouled it may be time to install a Muzzler. That is a unit that plugs into the wiring harness by one of the coolant sensors and trick the engine management system into
never shutting down cylinders. Costs about $80-120. to buy and about 1 mile per gallon in fuel economy. No one who ever installed one regretted it.

By the way, a lot of the warning lights you got always come on no matter what the issue is, only the codes are real.

Poolman

Just noodling , but I at one time had these codes , but without the cylinders being shut off. I researched this and read where the battery when it gets some age on it can be a cause for the problem. The car had about 30k miles on her and said what the heck. Been on the new battery now for about 20k more miles and haven't seen any more of the code problems.

2015RDXTech

The initial misfire occurred around 44,500 miles, when I had it towed to the dealer. The second misfire happened a couple hours after I got it back, so pretty much around the same mileage. Current miles are just under 46,000 and I dropped it off at the dealer a couple days ago.

It threw codes for cylinders 1, 5, and 6, and to my understanding, VCM either shuts off two cylinders or a whole bank, so I don't think the misfires are VCM-related. And yup, I found out from the dealer that a lot of those lights come on just to grab your attention. However, since the first misfire occurred, they cleared all of the codes and now no warnings come on except for the blinking check engine light.

As long as they can fix this whole issue under warranty and make sure VCM doesn't cause any issues, I'm happy. Unfortunately the warranty ended just a few days ago and I'm hoping they'll still cover this because it's documented and has been looked at before it expired. However, I had it in for service and replacement of some suspension components under warranty a few days before the initial misfire, and now the suspension problem is back and they refuse to fix it under warranty.

2015RDXTech

Yeah, this is on a brand new battery though. Surprisingly enough, right when I dropped it off for service and to fix the suspension a few days before the first misfire, the techs couldn't start the car to take it back into the service bay. They said the battery was bad and replaced it, so it had a completely fresh battery at the time of the misfire.

dave08902

The flashing check engine light says that you have a class A misfire and severe engine damage and catalyst damage will occur. Don't take this misfire lightly. This can cause piston, valve, head gasket and catalytic converter damage.

You should contact Honda Corporate and escalate your issues because the dealer didn't do anything but clear codes and send you on your way.

When the dealer cleared the codes, they also cleared the freeze frame data which would have shown when the misfire happened along with great troubleshooting data.

Causes of misfire are Spark plugs, coil packs, injector, low compression, clogged exhaust, head gasket, valve damage intake manifold, valve train timing, engine ECU, valve needs adjustment.

With the given mileage, the only things that may cause multiple misfires is spark plugs and coil packs. Cylinder 1 is in back by belts and 5 and 6 are by the battery. The misfire is not caused by the VCM because when in cylinder deactivation, the rear bank is turned off and cylinder 1 is in rear bank.

If the dealer won't repair your vehicle, i would start with new OEM plugs and swap the coil packs with the 3 good cylinders and see if misfire codes move to the other cylinder.

With the proper diagnostic tools, this misfire issue can be easily diagnosed very easily. Most dealers and aftermarket techs don't have this equipment or don't know how to use them.

Did you try using different gas stations?
Did you ever overheat the engine?

2015RDXTech

The issue with swapping the coil packs is that the misfire doesn't persist. It just happens at random times and goes away when I pull over and restart the car. However, it still happens from time to time.

I don't think it's bad gas because I almost always fill up at the same gas station near my house, except on long trips. The tanks of gas I was on when the misfires occurred were all from the same gas station as usual. I've also never observed the engine overheating; all the misfires occurred at normal operating temperature.

I'm really confused as to why the car misfires randomly, I thought that if it was a bad spark plug or coil pack it would misfire every time I started the car? I could be mistaken though.

This dealership has had my car for a whole 3 days now, no sign of it being done anytime soon unfortunately.

dave08902

When it misfires, do you get codes. Normally with cylinder 1,5 and 6 you will get P0301, p0305 and P0306. If you swap coil packs it may move to P0302, P0303 and P0304. Look at outside conditions when the misfire occurs, like moisture, rain and temperature.
With the coils swapped, even if it takes a while. The car should post a code, if it does not then you many not be letting it misfire log enough to post.
Misfires can happen randomly or constantly. If it is constantly then your issue maybe worse,
For example, when the coil pack warms up, it starts to breakdown on the secondary side of the transformer. This causes a weak or delayed spark which causes detonation, thus a misfire. You can also have carbon traces that the secondary voltage seeks and your spark becomes delayed when the primary coil collapses and fires the secondary.

You should try using a different gas station just to verify a fuel quality issue. I would choose a Top Teir gas station.

2015RDXTech

All of the times it's misfired, it's been pretty nice outside. Temperature has been in the high 50s-low 70s Fahrenheit range, no precipitation.

The codes it threw the first time it misfired were P0300, which is the general random misfire code, P0301, P0305, and P0306. Ever since the first dealership I had it towed to cleared all the codes, it hasn't been throwing codes. In fact, the dealership it's at right now couldn't find any codes on it from any of the times it misfired because the first dealership cleared them. I had them look in the AcuraLink messages menu in the infotainment system, because the 4 original misfire codes are still there. Haven't gotten any new codes since then. Does it not throw any new codes if the same cylinders are misfiring, and should it throw new codes if different cylinders are misfiring in this case?

It's only happened 3 times in one month, so we'll see how long it takes for the next misfire in case they don't find anything wrong with it this time either.

dave08902

This is from the Acura RDX Diagnostic service manual. Hope this explains things better.

2015RDXTech

The way I interpreted it, looks like it stored a pending DTC every time it misfired and the dealer should have been able to pull the pending DTC codes from after the first misfire? Maybe it would have been more helpful for the dealer to diagnose if I was able to bring it in immediately following the misfire, but the dealer in my area is the only dealer within a 1 or 1.5 hr radius, so they're usually booked days ahead.

dave08902

The misfire has to be long and severe enough to store a pending or permanent code.

Another thing that will cause a misfire is a bad can position sensor.

To be honest, I don't think the dealer will help you if there are no active codes present. Is the Dealer honoring the warranty, or is this all out of pocket? I hate dealers, even when my vehicle is under warranty, I still troubleshoot and repair my own car.
The dealers techs work by preset job hours. For example, if a job takes 12 hours and they get it done in 2 hours, they get paid for 12 hours of work. Just think how well the repair job is when they take short cuts and rush to get paid more.

I would start looking at finding a local shop near you that has a Picoscope. With this tool, they can diagnose your vehicle very quickly even when it is not misfiring.

2015RDXTech

They're covering this under warranty (I think) because I had the issue and had it taken to the dealer before the warranty expired. However they're not covering the other suspension issue I mentioned. I can only imagine how expensive all of this would be if I paid for it all out of pocket.

dave08902

Since it is covered under warranty. Let it misfire until the check engine light comes on and then take it to the dealer. The misfire needs to happen 89 times consecutively for it to post a code.

2015RDXTech

So I should let It run for a while when it misfires, and the check engine light will go from blinking to solid when it posts a code?

Brown13

If You have a code reader and a code was set.It will be there for a long time.The car must determine that everything is ok before the code goes away.It may be there for thousands of miles before it clears.Clearing codes is a thing of the past. You can also go to an auto parts store and let Them read the code.This is usually done for free.

dave08902

When you get a steady check engine light, then you posted a class B misfire. If you get a flashing check engine light you posted a class A misfire. Both will set a permanent code for the dealer to look at including the freeze frame data.

A simple code reader will only give you the generic P codes. What you need is a full professional scan tool or the Honda HDS. These scanners will be able to pull the freeze frame data and you can graph and watch the CMP, MAP, timing advance, coolant temp, misfire counter etc....
The scan tool, either a reader or a professional one is limited in troubleshooting misfires. What is needed is an automotive Lab scope with a cylinder pressure transducer to properly diagnose this issue. The labs-cope can actually look at your secondary spark event and see if there are any issues there. You dont need a code or an active misfire to look for issues.
Ask the dealer if the have a Picoscope and have them look at the secondary ignition, cam position and cam timing.

2015RDXTech

Dealer said they couldn't find anything once again, so I'm picking up the car tomorrow. I'll ask them about it while I'm there.

I don't have a code reader and the dealer says there's no codes anywhere except in the infotainment system so I guess I'm out of luck until the next time it misfires. I'm surprised they weren't able to pull any of that information at all, I would expect them to have more than just a basic scanner. Would an auto parts store have a more detailed scanner than the dealer?

I'll probably contact corporate sometime soon and see what they have to say about it.

dave08902

The dealer will not drive vehicle till they get a misfire. All they will do is let it idle in lot for hours and see if it posted a code.

The dealer uses the Honda HDS which is the best scanner for Acura / Honda vehicles. The auto parts store will only have a basic scanner that pulls generic data. The Honda HDS will have full access to all systems, freeze frame data and coding / programming.

If the car does not post any codes, the dealer will not do anything to fix it.

Go to Picoauto website and look at the video section on finding misfires. Be knowledgeable when you talk to dealer, they hate it so much.

My dealer hates me so much because they can't lie to me or sell me service I don't need.

fcostantini

Another good discussion of misfires is on YouTube at South Main Auto's channel. Search "South Main Auto Misfire" in the YouTube search bar and there are many different vehicles with misfires that Eric addresses, even some Hondas.