Another Issue! P0300 Misfire Car Won't Idle Properly
 

Ok this thing won't run for **** now. I hooked up the EU and it wouldn't start and threw the P0335 Crankshaft Position Sensor and a P0464 code something about the fuel level. So I disconnected the EU and just reverted it back to stock. Started it up and it ran but it was running crazy as if it was misfiring like the night before at the end of the test drive after I figured out the problem with ecu not getting power, it was the relay. I wait a bit, start it again and the car is shaking violently and making loud popping noises but it was able to stay on for a while. I turned it off waited about 2 hrs because I thought I was flooding the engine. I go now and its even worse, the exhaust sounds like gunshots and there is gas in the exhaust, its like half burned gas. The car won't stay on and when I hit the throttle no air gets sucked in by my intake it seems, its like it chokes. Its now throwing the P0300 code consistently.

Its not an ecu connection the car is completely back to stock the EU is out the picture. I am running the 440cc injectors so I'm guessing all the attempted starts have flooded the engine.

What should I do? I thought waiting would help the flooding but it hasn't. If I can get it to at least idle right then I can worry about the EU and use it to scale down the injectors.

Can someone confirm that I am right about the flooding? I'm pretty sure the wet exhaust confirms this.

I changed the plugs and I took a vid of the problem here it is, any help is appreciated

I'm fairly certain it's due to the injector size. The stock ECU, even in closed loop cannot pull the injector pulse far enough when you switch to 440s. The amount of fuel is drowning the plugs and forcing a misfire.

I had this issue with stock MAF, stock injectors and the cams. For some reason, the car would richen up and idle at like 11.x-12.x AFR from time to time and it would cause a misfire.

Stop driving the car and finish building it...

Thanks bro, the weird thing is at first when I installed the 440s the car ran fine just hesitated at WOT, but I did notice after test driving the car it would start to hesitate and do the same thing its doing now just not to this degree. The car hasn't been used since the injector install other then test drives and trying to start it when having issues with the EU install. I just don't want to finish the build and then not be able to figure out the issue.

Thanks for your input!

I do hope you get it sorted out man.. sounds rough. :(

Thanks.

Stock ecu and 440cc injectors is your problem. You need to compensate for the injectors.

Too rich, that explains why your plugs are fouled.

Ok went back to the stock injectors and still have the same problem, spark plugs are good. I pulled the coils and found that they looked like this,

http://i966.photobucket.com/albums/a...G/IMAG0194.jpg

http://i966.photobucket.com/albums/a...G/IMAG0195.jpg

http://i966.photobucket.com/albums/a...G/IMAG0196.jpg

4 of the 6 coils show the symptom in the above pics which looks like they got super hot and burned up. I checked the resistances on them. The two that look normal read 1.5-1.6 kohms, two of the burned ones read 1.6-1.8 kohms, and the last two burned ones read 2.1-2.3 kohms.

I'm not sure how the ignition coils got burnt up, maybe all the cranking I was doing when trying to install the EU? The EU is currently installed correctly and the car runs the same with it in and out and doesn't throw any codes any differently either way.

Replaced the 4 burned coils and the car fired up great. The CEL hasn't come on after the new coils but it still stores the P1320 misfire code as a pending code. I measured the resistance of the new coils to compare, the front bank new coils have a 1.5 kohm resistance while the rear bank coil has a 1.8 kohm resistance. The two rear bank coils (the ones that didn't look burnt) had a 1.5-1.6kohm resistance. I'm thinking they are the ones that are still causing a slight misfire that isn't that noticeable but I did notice when paying close attention and is probably whats making the car store the P1320 code as a pending code, I'll just replace them as well.

It's interesting what I found compared to other threads about testing the coils. In reality you aren't able to measure resistance on any pins (since the resistance is well above a few Mohms and other tools are needed to measure the resistance for other reasons) except for pins "1" and "2" (IB and G pins). 1.5kohms seems to be a good reading for the fronts and 1.8kohms for the rears. BUT since we can't fully measure all the resistances of the coil pins, 1 and 2 only tell us if they are misfiring at idle which mine were. I find it weird that some of my burnt coils had a higher resistance about 40% more then what they are supposed to be. If I didn't visually see the signs of damage I would have never guessed. The best way to test coils is to do as the fsm says to check for spark because resistance is not enough to say much especially when one of the visually burned coils had resistance within the same range as the new coils.