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Discussion Starter #1
Hello, all. I just purchased a 2006 Civic LX sedan with the 1.8L, auto trans (booo) for $500. The body and interior are nearly flawless, and the car has 180k on the odometer. I am the third owner. I bought it from the second owner with the understanding that "no one can fix it". The second owner bought it not running from the first owner, who's wife was driving it one day and it just quit, never to start again. The first owner took it to our local Honda dealership, who, after "50 man hours", called him back and told him to come get the car at no charge, because they couldn't fix it. This seems ridiculous to me. Shouldn't the Honda dealership be able to diagnose and fix anything on one of their cars? Anyway, the car came with a floorboard full of used ecm's, and someone tried very poorly at some point to install an aftermarket stereo. Otherwise, the car looks stock. I talked to one of the dealership mechanics and he told me that he had tried to help one of the other mechanics with the car, who was convinced the problem was ecm related. He said they tried several used ecm's, to no avail, and also changed out the fusebox. I don't know which fusebox he meant, but the one under the dash isn't bolted in. They also put in a new crank sensor. At some point, they literally just gave up and told the owner to come take it away. I've taken it on as a personal challenge to figure it out. The car has got to be worth more than $500 even as it sits, and I suppose I could part it out, but I think it could still be a good little car, and I want to give it another chance.

So, here's what she's doing:

Crank, but no start. Hits with starting fluid, but not consistently. The ecm isn't communicating with the obd2 port. I checked all the fuses, the ground on the side of the intake, replaced the fuel pump relay, and sent the original ecm off to be refurbished. When the key is turned to the "on" position, the fuel pump doesn't prime. I checked the plug on the fuel pimp (<--- typo, but I'm leaving it), and there was no power to the plug. I pulled the fuel pimp (<--- on purpose that time) relay and used a jumper to power the fuel pimp. The pimp runs constantly with the key in the "on" position, so I know it's functioning properly. Still doesn't start. All the fuses are getting power when they should. I don't think I'm getting any injector pulse or spark, at least not consistently, or it would have run on starting fluid, if only for a few seconds. The main fuse under the hood is good, as are all the others. The ecm has been verified to be good. What other reason could there be for the ecm not to be communicating with the rest of the car? Whatever happened to the car occurred suddenly, while it was running down the road. It HAS to be something simple that I am missing. This is my first 8th gen civic, and I'd really like to be able to enjoy it, therefore I have come to the true experts. Any input/suggestions will be very much appreciated!
 

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Main power relay? May sound dumb but does vehicle come out of park with the key? Just wondering if it’s an interlock issue on the start. Must have main relay energized then that will power up other items.


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Why do you believe that? Could be seeing multiple controllers were used.


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If it’s cranking but not starting, for any car at lest. Make sure the engine is getting air, check the fuel injectors, spark plugs, and finally the timing belt.
 

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I've seen ignition switches fail on these and cause similar issues. You'd want to check all of the multiple outputs from the ignition switch.
 

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Discussion Starter #9
Answered in the order of the responses:

1.The reason I think it's some break in the harness, is because all my engine components seem to be working separately, but they don't seem to be getting any signal from the ecm.

2. Does the 1.8L have a timing belt? For some reason I thought it did not. Surely the dealership would have checked that. Also, if it tries to run off starting fluid, wouldn't that be a sign that I have air, compression, and spark?

3. I have thought about the ignition switch, but the fuse box, fuel pump relay, etc are getting switched power when i turn the key.

4. I really think there's an issue between the underdash fuse box and the underhood fuse box. I don't relish the thought of tackling that beast, but I don't know where else to turn at this point.

Does that black junction box thingy that's mounted to the side of the head near the thermostat housing where that major ground is ever go bad? I wonder what you call that thing?
 

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Not sure what you are talking about near the thermostat housing. Do you mean the EGR valve?

EGR valves can go bad in that they either won't open (engine-out emissions are out of compliance and a code is set) or it sticks/leaks EGR (engine may stumble/run poorly, and may not start at all).

If the EGR valve is stuck open, the position sensor should tell the ECM "hey, I'm not closed so set a code". If the EGR valve is commanded to move to a certain position and it doesn't , it will tell the ECM to set a code. Pretty much any fault with the EGR valve will set a code except if the valve is leaking but the valve is seated.

If you have EGR flow during starting, the engine might not be able to fire because it can't get enough fresh air. But it would run on starting fluid until it is gone. However, I would think the engine would try and would kick a little. If it were me, I'd probably take it off and make sure it isn't damaged. You could even make a blockoff plate out of solid gasket material to see if that solves the issue.

In case you don't know, EGR stands for Exhaust Gas Recirculation. Basically a small amount of exhaust gas is directed back into the intake manifold where it combines with fresh air. Once in the combustion chamber, the inert exhaust gas slows down the combustion of the air/fuel mixture which results in lower peak flame temperature. NOx is formed when combustion occurs at high temperature, so adding EGR reduces the amount of NOx formation.

Unlike a diesel, a gasoline engine really can't handle much if any EGR at idle. So typically the valve is closed during startup and idle. The valve will change the amount of EGR depending on the engine temperature and throttle command.

Good luck...
 

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The first place to start is to get the ECM to communicate. You will need to take a systematic approach to this. You'll need a wiring diagram. You'll need to check the communication lines, power and ground to the DLC, and then powers and grounds to the ECM.

Here's where I'd start:

Does the check engine light illuminate when you turn on the key?

With the key on, do you have a 5v reference under the hood from the ECM? There are numerous sensors that use a 5v reference voltage that is supplied by the ECM. The TPS, MAF, MAP, ECT, IAT, etc. all use a 5 volt reference from the ECM. If that 5v reference is missing then the ECM is offline. You'd then want to find a wiring diagram and then check all the powers and grounds to the ECM.
 
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