First of all, please forgive me if this thread is in the wrong place. I seem to be Forum Navigationally Challenged.

I have a 1999 Honda Accord 3.L V6 EX coupe with 57ish thousand miles that has an engine shut off issue. I wouldn't call it a stall. It's like the passenger reached over and shut the car off with the key.
Recent work done...Coolant fan control module replaced and new ignition switch. The problem started long before this work.

I've read hundreds of posts and browsed the DIY section but can't seem to find what I'm looking for. I have the "how to", I just need help with diagnosis. As many posters have mentioned, I don't want to just throw parts at the problem but admittedly I've done some of that recently out of desperation. Let me explain what's happening.

The car will just randomly shut off. There doesn't seem to be any rhyme or reason as to when it happens or how often it happens. Cold, hot, dry, rainy, uphill, downhill, stopped at idle, driving down the interstate, or rpms. None of that seems to matter. I will say though that it when it does happen the engine has always been at normal operating temperature. After a shutdown it always starts right back up. The first time it happened I pulled onto the shoulder of the road and instantly panicked because I thought my catalytic converter was going to catch the grass on fire. But it started right up, and I drove off. The next time it happened I didn't even pull over. I just put it in neutral while still rolling and started it back up, then kept driving. It will sometimes go months without shutting off, then it may do it multiple times in one day or once every couple of days. Then it won't shutoff for weeks, even months like I mentioned.

I checked the car with my OBD reader, and it didn't throw any codes. I took it to my mechanic who is the only person who has worked on the car, besides myself, since the factory warranty expired, and he couldn't pull any codes either. He kept the car for a week trying to get it to stall but couldn't get the car to duplicate the shutdown symptom. They were using it for a parts runner, (with my permission), and it still wouldn't shut down for them. He said that since he couldn't get it to duplicate the symptom, he couldn't do anything unless I just wanted to start throwing parts at it. After reading a multitude of posts on forums and google about ignition switches causing the car to shut off, I told him to put a new ignition switch in the vehicle and maybe we'd get lucky. We didn't. It shut off on me the next day after I picked it up from him. Then it didn't shut off for three months until yesterday when it shut off 4 times. Luckily it started back up each time and it didn't leave me stranded sitting on a railroad track. I've been delegated to the right lane everywhere I go for fear it will shutoff and not start, leaving me stopped in the middle of the highway. Probably during rush hour.

I'm about to start radiation treatments and I just can't trust this car not to shutoff and cause me to miss an appointment. Or block the whole parking garage entrance where other patients are trying to get to their appointments. That would be bad.

The car runs perfectly and tune up components have already been eliminated. I am hoping that someone before has stumbled across something in the past that can help because I'm at my wits end. Or if someone can give me a top ten or top five things to check that might be the issue so I can try to eliminate things systematically instead of trial and error. I know that there are different systems on any vehicle, electrical, fuel, etc. There has to be a breakdown somewhere in one of these systems, but not a total breakdown hence the intermittent aspect. Something that might not be obvious like bad engine ground to the frame or loose wire at the fuel pump or something. Fuel pressure has been checked as well.

Thank you for your time and I appreciate you all for any insight you might provide.

Frustrated in Tampa

 

Have you checked the EGR valve and passages? I previously had a 97 accord with I similar symptoms and that was the issue.

 

RAL91 Thank you for your reply.
Was your Honda a V6? And how many miles were on it?

Usually when it's an EGR problem the computer will through a code. P0401 could mean one of the following: 1) Differential Pressure Feedback EGR sensor is faulty 2) There is a blockage in the EGR passage, most likely carbon buildup 3) The EGR valve is faulty 4) The EGR valve may not be opening due to a lack of vacuum.

My car only has 57,800 or so miles on it and does not throw a code. Out of the three trusted mechanics that have looked at this engine none of them suspected the EGR valve or passages. And you would think that they could make a couple of hundred easy bucks if that's what they thought it was. So going on that I personally have not pulled the airbox duct off and the throttle body and disconnected all of the various sensors and hoses then pulled the intake manifold off to see if EGR port/s were blocked. Mainly because even if the passages were blocked, we don't think this would cause a shut off condition of the engine. Just saying.

Thanks again for your reply and for trying to help.

 

Mine was a 4 cylinder and had around 250k miles when this was happening. I don't recall if it was throwing a code or not. When I did open it up to clean the passages, they was so much buildup that I was surprised that the car ran at all.

Very well could be a different issue with yours, especially seeing as the miles are so much lower. Thought I would share my experience in case it was helpful.

Good Luck!

 

It's all good. I appreciate everyone who tries to help. Future good luck to you as well.
Thanks,

 

I have a 2000 accord with some problems like yours, what does an EGR go for?