Car is a SH-AWD with 65,000 miles

This winter my RDX began running rough for about 3 seconds upon first start of the day. I assumed it was just due to cold temps and direct injection. Once it cleaned up, it ran fine and no check engine light and started fine after sitting for 9 hours while I was at work. This occurred for a few weeks. Then the running rough lasted about 5-8 seconds and would do this when I would start it after work. Then it started running rough after it would initially clear up but under light throttle shortly after start up but would clear up when I let off the throttle or after a few minutes of driving. Once cleared up, it was totally fine.

This past weekend I started it, it was running rough so I lightly revved to 2000 rpm. This threw the CEL for the first time and everything else on the dash lit up. I scanned it and got #2 cylinder misfire. Troubleshooting, I swapped #2 and #3 coil packs. Cleared the code and had to disconnect the battery to turn off all the other warnings. I then lightly drove to a long stretch of road and performed a max effort launch up to about 100 MPH. Engine ran perfectly. Go home shut down engine. Next day no problem, go to work. Leave work that day, running rough on start up and with light throttle. Got on main road, light acceleration, running rough so I stepped on throttle and it really ran like crap. CEL came on and limp mode. Pulled over and ran codes. #2 cylinder misfire. Erased code, drove very lightly for 5 minutes then no problems, got on highway, accelerated to 80 MPH, no problems. Got home and pulled #2&3 spark plugs. Both looked good, I hit both with a wire brush but reinstalled #2 in #3 cylinder and 3 into 2. Then drove to Autozone, no problems. Had about 1/5 of a tank of fuel (93 octane) and dumped a bottle of Techron into the tank. Drove (couple of swerves of steering wheel to slosh it around) and drove it like I stole it all the way home. No problems. Fired it up this morning no problems drove 40 miles to work, had 20 miles left till empty and filled tank.

This is my first direct injection car. I feel like I ruled out the coil pack and spark plug. The only other thing I can think of is the injector. I don’t know exactly where they are located or if they are accessible to replace. I don’t want to bring it to the dealership, at least not yet, until the problem is constant.

Any help troubleshooting this would be greatly appreciated.

 

I heard head gasket leak can cause misfires with coolant getting in the cylinder. Is your coolant level normal?

 

I will check it the level at lunchtime.

Yesterday when I swapped the spark plugs (this was after a 40 minute drive) I looked into the cylinders and could clearly see the “A” on the top of the pistons. They were a dull black and didn’t look “pressure washed”.

 

For clarification: you haven't had any issues or codes since running the Techron thru the system?

Codes aside, how does she drive? Any noticeable reduction in power @ WOT? I'd assume you'd have a more sluggish response running lean due to a clogged injector.

Since you can wrench, it may be worth adding an oil catch can between the PCV valve and intake - seems to be something direct injection motors benefit from.

 

When it’s not running rough it runs like a raped ape. No codes or running rough since I added the Techron yesterday.

However, I just check the coolant reservoir and the level is slightly below the minimum mark. I’m now beginning to believe that it’s a head gasket.

I feel replacing that is past my abilities for this engine. I’m thinking of bringing it to the dealership but I’m quite concerned what they will charge me.

Anyone know if head gasket failure is common on these engines?

 

it's not as common on the 2.0t in our RDX but it is very common on the Honda 1.5t engines. Top off the coolant with Honda coolant and monitor the level until you take it in for diagnosis.

 

I stopped at the Acura dealership on my way home today. They are going to diagnose it next week. Fortunately and very surprisingly I still have a few months and 10,000 miles left on the original 6 year 75,000 mile power train warranty!!! I guess I’ll find out for sure if it will pan out next week.

When I got home as soon as I shutdown the engine I popped the hood and went straight to the coolant reservoir, I could hear, see and feel it bubbling…. So I feel pretty confident at this point it’s a head gasket.

 

That actually seems pretty normal to me, based on other cars. Hot engine shut down is still hot, cooling has stopped, coolant continues to thermally expand. I'll take note of that the next time my wife's RDX gets driven.

 

I just went through this and it was a coolant leak on my 202 RDX with 54k miles. i was still under warranty so i ended up getting the head replaced. keep a eye on coolant levels, thankfully i also got my fuel pump replaced and intercooler too, all under warranty.

 

So the dealer determined it’s a blown head gasket or possible crack. The installed a plastic funnel like device on to the radiator fill and topped off the coolant. Then started the engine. They sent me a video of this and bubbles were pushing up through the coolant.

luckily for me I am 10,000 miles and few months shy of the original 6 year 75,000 mile warranty and Acura is covering this!!!!😃

The service rep said they will examine the head for cracks and I asked him to have the tech please inspect the back side of the intake valves for carbon buildup.

They are supposed to get started on this today or tomorrow based on part availability.

 

Unfortunate that this is happening but I'm sure you are glad you are still under warranty.