Sythe

This is a little long but I’m trying to give you guys all the info I can to get the best help.

As stated above - 2013 RDX AWD Base model. Mileage 232500 mostly highway miles.

Vehicle History - I drove vehicle with a misfire that occurred around 120K miles and it got progressively worse over tim. I had all the warning lights going on the dash - it ended up needing a valve adjustment, which occurred at approximately 190K miles.

All the warning lights went off after valve adjustment, but shortly thereafter, the Check Emissions light came back on - I used Cataclean and Check Emissions light went off for a bit but did eventually return. I tried Cataclean again but the light never went off after the first time. It has been running like crap again since 210K miles (I’ll explain below). I scanned the codes and got P0420 & P0430 for “catalytic converter below threshold” for both banks one and two. So I purchased the replacement Front Catalytic converters. My mechanic replaced the bank 1 Cat and and the check emissions light has been off now for a week. He rescanned the OBD and now there are no pending codes. So I don’t see a reason to replace the bank 2 Cat since the code is gone. The car is still running terrible however.

Onto the explanation-

I drive approximately 150-250 miles every day. Car starts fine and usually drives fine until it’s warmed up. When I’m cruising on the highway at about 65-70mph the car is at about 1800-2000 rpm. If I try to gradually accelerate the car almost always vibrates/judders violently until I release the accelerator, and if I want to actually accelerate, I have to step on the accelerator harder so that it downshifts. If I put the cruise control on at those speeds I can see the RPM meter bounce a bit. Typically I drive at about 82MPH just because the car seems to behave at that speed/rpm level. Once I’m off the highway, it still has a problem accelerating unless the rpm’s are already over 2500rpm (because it’s hot at this point). On my way back after work, the judder seems to be even worse, and sometimes I have to leave the car in sports mode just to keep the rpm’s from dipping to that crucial 2000RPM level.

Oil changes have been maintained, and I only use 93 Octane fuel. I have changed the air filter regularly and I just installed a K&N Air Filter.

Unfortunately I have not changed the transmission fluid, or any other fluid for that matter, but from what I’ve been reading, it may be worse to change the tranny fluid at this stage, given the mileage it has traveled without one.

Tranny fluid change was going to be my next step until reading about it, now I’m not sure.

I admit I certainly could have taken better care of it but this is where I’m at now. Any tips, thoughts or suggestions would be helpful and greatly appreciated!

DCS

Compression check should be priority one. If compression is good then new spark plugs and coils. If compression is bad then recheck valve clearances.

altair47

If you've driven 70,000 miles with a misfire, you've most likely destroyed your catalytic converter and burned the valves. If instead of a 40,000 mile transmission fluid service change, you never did it, then most likely your friction discs are already ready to die or after an oil change. I recommend that you stop torturing the car, trade it in or junk yard, because you are unlikely to want to replace the engine, transmission and catalytic converters.

Falconee

Fist off how much oil are you burning?.. and change the transmission, diff and transferase fluids. That don't change the transmission fluid because it may be worse doesn't apply when telling you its not working correctly. The 6 speed burns up fluid fast every 30k miles would be a good for a change interval. Also that judder you feel is also probably the cylinder deactivation mode kicking in on the highway combine that with original motor mounts the car is going to run funny. Change the tranny fluid 3 times and report back. its about 3.5 - 3.8 liters every change.

Sythe

who said I was burning oil? I’m not.

When the car shifts it’s actually pretty smooth. so what I was trying to ascertain is whether or not the really violent vibration when trying to accelerate on the highway (at around 1500-2000 RPM when the car is in 6th gear) is in fact a transmission issue. Even the slightest bit of acceleration cause the vehicle to vibrate violently and I have to release pressure from the gas pedal immediately and press hard enough on the gas pedal next time to force it to downshift.

As stated, I had CEL codes of P0420&P0430, so I had one of the front catalytic converters replaced and the check engine light has stayed off since that repair (2 weeks ago). I was hopeful that was going to also fix the acceleration issue but it did not.

I was prepared to change out the 2nd front catalytic converter, but since the CEL has remained off, I’m torn between replacing it just to see if that fixes the issue, or if I should divert my attention elsewhere. According to the first reply, I need to have the compression checked. I am also going to replace the spark plugs for good measure. It was done about a year ago but for me that means 50,000 miles.

Now knowing what I just explained, is changing all of the fluids you mentioned still the first step you would take?

Falconee

I figured you were burning oil because that is a classic symptom with clogged catalytic converters. If you aren't burning oil that's great and you should probably not change the second cat. I also don't see why you would bother doing a compression check if the car has adequate power seems like a waste of money. I would change the spark plugs with OEM NGK (get them from a local part store or honda.. amazon sells lots of fakes.)

Its interesting that you mention a violent vibration.. with your mileage and the age on the car I bet your driveshaft U joints are gone! I had that on my last CRV and it was a classic rumble under your seat when accelerating and at certain RPMs. Get under the car and see if there is any movement whatsoever on the rear u joints. The center driveshaft bearings is also something that can wear out. I haven't looked on the rdx but driveshafts can be rebuilt by a local shop if replacement u joints are available or get an aftermarket one. OEM honda will be expensive if thats what it is. Still change out your fluids... what color is the transmission fluid on your dip stick.. it should be bright red if it is black change it out with ATF-DW1.

Poolman

I had a fit trying to find the vibration in my ride. Posting a link from what I did to make the fix. Don't know if it will help or not, but it's there .

https://acurazine.com/forums/2g-rdx-...udder-1002458/

dtownfb

Is your check engine light still on? If so, I would change the O2 sensors.

I would change the transmission fluid since it's pretty easy. New fluid is your friend with these transmissions.

If the transmision is switching smoothly except for the situation you describe, it's likely something else.

Sythe

I wanted to follow-up and thank everyone who provided me advice, and to Falconee, as you were right on the money.

I did a triple transmission fluid change and I’m happy to report the problem is gone.

Instinctively, I totally thought this would have been something else.

I’m glad I didn’t quit my day job and become a mechanic 😂.