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This car showed up a few moons ago and I never got to see the diagnosis through, but I thought I’d ask about it anyway should somebody know about a pattern failure. As the title states, no misfires despite the code. I asked my customers (hubby & wife) a couple times if they’d ever experienced a misfire and they both swore the engine had always ran perfect. (There was another code for high idle control speed and I just can’t remember what that was, but testing per the FSM suggested the coolant being a little low was possibly enough to cause that code.) The power balance test showed every cylinder making a contribution, the engine ran great, and there was no evidence of any vacuum leaks. For what I can remember, I think I found the fuel trims to be adding just a little more fuel than I thought it should while cruising. Fuel pressure was steady and in spec so I tested EGR operation. The EGR valve was opening and closing as it should, but the engine wouldn’t stutter or stall when I commanded it open at idle. The engine made absolutely no change in idle RPM or idle characteristics. So what I want to know is if the lack of EGR flow is enough to cause a misfire? I’d guess that it could be a possible lean misfire or predetonation from hot cylinders. Any ideas would be great and I’ll make sure not to wait months to sign up for a car forum to ask an old question next time around.
Thanks!
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Lack of EGR should not cause misfire. Now a stuck open EGR on the other hand, absolutely. The whole point of EGR operation is to reduce NOX emissions.
Well, based on the fact you commanded the EGR valve to open and it didn’t stutter and stall then something is definitely wrong.
As for why a P0300 and not an EGR code, I cannot say, but as always, fix the things you know are wrong and sometimes other seemingly unrelated things start running right…
-Karl
That engine is prone to clogging the EGR passage in the back of the intake. It often sets a misfire code but not an EGR code. Oops, just saw you posted a 3.2L engine.
That means it’s likely you’re likely dealing why a TL not an RL. The RL engine is the 3.5L. That said, This video is what you need. You won’t have to go this far (removing the intake), just remove the upper intake plate and clean the ‘ant farm’ EGR passages. You can reuse the gasket.
It was definitely an RL. I just got my displacement wrong. Calling it an ant farm makes perfect sense. Thanks for all the replies.
If it’s a 3.5RL the passage is in the back of the intake. There’s a small tube that connects the cylinder head to the passage in the back of intake manifold. Once you remove the tube there is another plate on the back of the intake. All 10mm fasteners BTW. Remove that plate and clean the passage behind it. You may need new gaskets for the plate and the tube. They aren’t expensive and any Acura dealer would likely have them in stock. It’s fiddly work so be prepared to settle in.
Good luck and keep us posted.
Like I said, this was a few moons ago and the car is long gone. I should have wrote the orignal post a little better. I was just reminded of the car and thought I’d ask about it just to try and satisfy my curiosity.
When I was doing the diagnosis, I was pretty sure the P0300 and the EGR were related even though it would be counterintuitive as ShopTech implied. I told my customer that I found a decisive problem but couldn’t promise it would solve the root problem. All I had at the time for shop reference was All-data and I couldn’t find any information to back up my suspicion. I did’t have an idea what to charge for repair labor either so we went with R&R labor for the intake manifold which was in the ball park of four hours. It was too rich of a gamble for the customers and I haven’t seen the car since.
To have a valid question for you Eric, what would you consider fair labor to clean the EGR ports on the 3.5?
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