Last night, as I was tooling down the highway, I stepped on the gas to move into the left lane to pass a car.

Immediately, my Check Engine and SH-AWD idiot lights popped on and the mini-display between the gauges popped up with Check Engine Emissions and SH-AWD.

The nav display also brought up messages with a little more detail with a code 77 and another for the SH-AWD. The Voice said something about the engine and the SH-AWD malfunctioning and that the vehicle may not handle as well and the diagnostics asked me to pull over at my earliest convenience, stop and start the vehicle and see if the problems recur.

I pulled over as requested, threw the car into park and sat for a few minutes wondering what the hell was going on. After waiting, I started the car up and the SH-AWD light shut off after ignition, like it usually does. The Check Engine however, stayed on, as did the message about Check Engine Emissions. After getting back onto the highway, the SH-AWD message lit up again. I toggled through the gauge info display and according to the animated display, power was indeed only going to the two front wheels. Strange!

So I followed the next option available from the info screen, which was to call my Acura dealer (Pohanka) for service. I did so and made an appointment for this morning, since I was already on the road and nowhere near the dealership. On the way to the dealer this AM a third warning popped up about the engine (D000299?) and the info said that the engine was not running optimally and may exhibit a performance loss.

Dropping it off at service, I described the problems in detail and asked two service guys if they had heard of any problems with the RDX. Both said no. One gave me the option of waiting "about an hour" for them to give the vehicle a once-over and possibly just reset some bad sensors or what have you. I said no, I had to be at work so he pointed me to the waiting area for a loaner car.

Strangely enough, although the loaner was offered for free, I was informed that I am expected to return it with the full tank of gas it started with. Side effect of high gas prices? Because none of the service loaners I've ever received for my previous vehicles expected me to pay for the fuel used and I certainly didn't expect it at an Acura dealership.

 

how many miles do u have

 

Oops, I knew I forgot something. I was thinking about that when I typed it in too. But little emergencies cropped up at work and distracted me from adding it to my post.

More than 7000 and less than 8000, I don't remember exactly -- I think it's somewhere in the lower half. Also, got my 2008 RDX on the last day of September, so it's just a hair over 5 months old now.

 

Got a call back from service.

They said were ordering a new CATALYTIC CONVERTER and should be replacing it Friday!

Wow.

 

OK.

Just got off the phone with my service guy. Actually a few minutes ago, since I was ranting a bit about the explanation to my fellow workmates.

Apparently, it goes like this:

When you drive the RDX with less than a quarter tank of fuel, the engine operates in a "lean mode" which runs the engine and exhaust hotter and as a result can cause catastrophic failure in the catalytic converter (his exact phrase was "melt"). The diagnostic code I got for the SH-AWD apparently means nothing, because he said that any time the Check Engine light comes on, it will come on too. He said VSA the first time, but was quick to correct himself after I questioned him about it.

He claimed to have spoken with the vehicle's engineers about it, but apparently it took the 8 hours since I dropped my car off at the service bay for them to get the information back to me. I know for a fact that they drove it straight in to look at it as soon as I pulled up.

I have NEVER had a warning light come on except for the low fuel indicator and letting me know it needed an oil change. Is this a common occurrence? Has anyone heard about this at all? Because I have NEVER EVER heard of this before.

W T F ?

 

Clarification.

Spoke with another service adviser at the same dealership since I didn't quite understand the nature of the failure after looking up information on catalytic converters. The "lean mode" changes the the fuel-to-air mixture and makes it richer, allowing unburned fuel to pass out through the exhaust, which damages the catalytic converter. He said he has seen one other RDX do the same thing and that it's a standard feature of many modern automobile engines.

That re-explanation jives more with what I read about cat failure, but I'm still not entirely happy about the situation or believe that cars are designed that way.

 

Oh man, I'm sorry to hear about your troubles. It could be crappy gas. What brand of gasoline do you use? And do you use premium? I always run my tank down pretty low, but now I'm going to reconsider. I have never heard of a car running lean with 1/4 tank of fuel, sounds like BS to me. Good luck with the repairs, and keep us posted.

 

Always premium, as prescribed, but not always the same brand. Usually it's Exxon (and I used to swear by Mobil when they were Mobil), but I have dabbled in other carriers since I don't use a gas card and my preferences aren't always available when I fill up.

I have a very hard time swallowing the "quarter tank lean mode" explanation -- same goes for the "me too!" sympathetic triggering of the SH-AWD indicator and self-diagnostics. If the diagnostic information the vehicle provides isn't right, something is seriously wrong here.

After I get the RDX back, I will attempt to religiously prevent the tank from dropping below the 1/4 mark (even though there isn't one on the gauge!) and if it eats the cat again, I'm going to have to start screaming foul.

 

I picked up the car tonight and here's irony for you.

They were nice enough to wash and detail my car inside and out, but my car arrived at the dealership with a quarter tank of gas and I picked it up with something like 1/16. Range was reporting only 32 miles left. Guess their warning doesn't matter when they're the ones burning the fuel??

 

I've never heard of this.

The ECM (Engine Control Module, somtimes called ECU, etc) does receive a tank level signal over the OBD bus. It can be viewed with a scanner, outputted as a percentage remaining. Your service dept's logic is that when the tank is low, there's lower pressure being fed to the engine. The ECM therefore needs to compensate by increasing the injector base pulse width (add more fuel) to get the air/fuel ratio back to 14.7:1, called "Stoichiometric", which is the ideal ratio for the cataltytic converter.

Here's the rub, though. Fuel injected cars have high pressure fuel systems (~45 PSI in many cases), and in nearly all cases, are a recirculating system. This means that the fuel pressure is regulated by a (who would guess...) Fuel Pressure Regulator. The excess fuel is returned to the fuel tank.

This means that, regardless of the fuel level in the tank, the injectors will see the same pressure, and therefore deliver the same fuel for a given pulse width.

So what you've either been told, or the way you're relating it here, doesn't make much sesnse to me. I do, however, understand that information might have been accidentally misrepresented somewhere along the line. I also don't know it all, so maybe there's something unique about the RDX.

Something else to consider - modern ECMs actually have methods of detecting fuel quality (in the most basic sense, the octane rating), and can make adjustments based on the detected quality. Cheap gas can cause problems.

Anyway, I hope that helps, at least a bit.

-Mark

 

Never heard of this, although I usually keep the fuel above the half mark in colder weather but summer I usually run it to the end on both my cars.

Do you drive your car hard? I usually like to run my cars in to the vtec range a few times a week just to "clean" everything out.

And I got the check emission light but usually it came on with the check VSA and a gas cap tightening fixed the problem. Never SH-AWD.

Sounds to me your techies can't figure out what. CAT converter is pretty expensive item to replace ....

 

Uhmmm yeah, could you imagine almost every car out there would be blowing up their CAT's

I've maybe (maybe) filled up the tank like 2~3 times. I'm driving on little over 1/2 tank and way under 1/4 tank quite a bit. So yeah that should tell you something there. I'm right around 9800 miles too.

 

First, forever and a day, Toyota and Lexus have always disabled ABS pumpmotor functions, except for ABS itself, when there is ANY CEL. I have never heard an explanation that held water.

And I don't believe any of the failure explanations the dealer has given you will hold water either.

 

^^

 

NEVER kEEP YOUR TANK @ or below a QUARTER TANk, that is a NO-NO.
Oh, if you can, you SHELL GAS - w/ the newer nitrogen type fuel(i tink thats what it is) it's richer in gas.

 

i guess everyone has overlooked this

http://techinfo.honda.com/Rjanisis/pubs/SN/B070800.PDF

its a TSB at the least. and my service manager also made me aware of it on one of my first visits.

 

Parallel parked my SHO with 1/8th tank on a steeply rolled street for a couple hours and couldn't get it started because the gas rolled away from the sending unit/pump. But I would think that they would never manufacture a car that couldn't RUN OUT OF GAS People run out of gas all the time, if it screwed your car up that much they would have a warranty disclaimer and more than just a yellow idiot light.

 

please tell me how one could go about a car that could not run out of gas? i dont see how this is possible with gas powered engines? unless ur just being sarcastic then i understand your post of course

i approach it from a common sense standpoint: no gas in your tank? i knew this when i was 15!! the pumps are going to try as hard as they can and suck all the SHIT in the bottom of your tank to get something to the engine; ie not good for the engine u dont need to be an engineer to understand this. When the water runs out of the brita YOU FILL IT BACK UP no squeeze shit out of the filter!!!

 

I had the same problem and my dealer here in San Diego did a reprograming (something like reflush) and it fix...They did not change any thing..