Misfire

Brian Technician Nevada Posted   Latest   Edited  
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Driveability
2000 Honda Civic EX 1.6L (D16Y8) 5-spd (S40)
P0300 — Random/Multiple Cylinder Misfire Detected
P0301 — Cylinder 1 Misfire Detected
P0302 — Cylinder 2 Misfire Detected
P0303 — Cylinder 3 Misfire Detected
Misfire P1399

I need some real help here. Customer purchased a 2000 honda civic 1.6L with manual trans 5speed form someone that was recommended to him by someone else and sold him pretty much junk. This car came in with check engine light on with codes p1399, p0300,p0301,p0302,p0303 & p0304. Found the timing to be right on the money. Found the valves to be out of adjustment so I figure that would fix the problem but didn't it got better but not fixed. After looking further I found a big intake leak and once again I thought I have found the problem but once replacing the gasket and sealing correctly the car still had a misfire especially under load. Check engine light would be flashing. Another problem I found was the plug were the wrong ones and replaced the with cooper ngk plugs. Still having the issue there and frustrated over this I noticed another problem the ignition coil and cylinder 1 wire were arcing. After all these problems found and fixed the car still had a misfire. I decided to put a distributor on this hoping it will fix it and yet again nothing. I scoped out the ICM control from ecm to distributor yel/green wire and noticed the square wave signal going in and out. At idle I get a 7v square wave and under load was more noticeable when signal would drop out. I decided to run my own wire to eliminate the possibility of bad wire. After doing this the car ran a lot better under load no more check engine light flashing but at idle I would feel a slight misfire. the light wasn't coming on as fast as it did before. The next morning I come in and started the vehicle and still felt the slight misfire there but not check engine light and so I let it idle for about 10 min and once I get back to the car to take it for a drive the light was lit and code was p0301 & p0303. Car runs better but still triggering the light and I get it to misfire with MIL light flashing but less than it did before just running out of ideas of what it could be. Any Help would be appreciated. According to the customer the heads were machine and distributor replaced with timing belt. None of these look new to me by the way. What am I missing here?

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Luis Technician
California
Luis Default
   

What is the engine vacuum reading at idle, did you check fuel pressure and fuel quality? Water contaminated fuel? Where are your fuel trims at? Did you try disconnecting front O2 sensor to see if it runs better check the pcm ground at thermostat housing remove 10mm head bolt clean bolt threads and contact area

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Victor Owner/Technician
Florida
Victor Default
 

A running compression test might be useful.

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Anthony Technical Support Specialist
Pennsylvania
Anthony Default
 

Hi Brian: You haven't really given much information here. You list all the classic symptoms of clogged EGR ports. Probably cylinders 2 and 4. While you found different areas of concern, the diagnostic approach here confuses me. What was your game plan in going after this? In short, what were you tasked to do? If you were tasked to find and repair the misfire, that's one thing. If you were…

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Brian Technician
Nevada
Brian Update
   

I did forget to mention here that I have done relative compression test and also with the gauge. Even after having good compression I still decided to do the leak down and passed. This vehicle has no EGR. Ive done a vacuum test at idle and was 20in. I Have smoked the engine and find no leaks. Ive also current ramped the injectors as well. Im going to run a running compression test today since I…

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Eric Mechanic
North Carolina
Eric Default
 

So is it misfiring at idle only now or under all loads? What are the fuel trims doing? Any carbon tracking in the cap? What are the compression numbers?

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Brian Technician
Nevada
Brian Default
 

its misfiring at idle and less underload after running my own wire from icm control to distributor. I had a very erratic pattern before putting my own wire now its better but my concern is that the on/off 7v from icm sometimes drops around 6.5 to 6.4volts. I believe the ecm is no good but I want to know if that drop in voltage is normal which I believe is not. I put in a help request on…

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Joel Diagnostician
California
Joel Default
   

the job of the ecm is to ground that wire icm control, the voltage is produce by the ignition module I have seen that voltage at , 5 6 ,9 12 volts , the ecm pull it down to ground to trigger. in that video I am explaining how taht system works . youtu​.​be/tUJjslv_m7c

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Darren Mechanic
Wisconsin
Darren Default
 

What’s 5 gas say during misfire.

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Brian Technician
Nevada
Brian Default
 

Don't have a 5 gas unfortunately

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Randy Diagnostician
California
Randy Default
 

Did you check keyway on crank pulley

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Brian Technician
Nevada
Brian Update
 

Thank you all for the response. After doing all this work to this car and replacing many parts I replaced the ECM and the ignition control signal was back to normal so I thought. When first scoping the icm control the signal was bad and ran my own wire from ecm to distributor and signal was restore way better than what it was. After doing so I still notice the signal had glitches in them and…

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