Cylinder 4 misfire

[darrinos]

So I put in a new ECU/IAC....2000 I30t....and finally got the car to start. But now I'm getting 2 codes. One is PO1320, and the other says that cylinder #4 is misfiring. I replaced the coil...same code, still has misfire. I swapped coils between cylinders 1 and 3 to see if maybe the coil was bad, and reader still says cylinder 4 has misfire. I put on a new harmonic balancer and I read somewhere that the crankshaft sensor could cause this error, so I'm going to check that. Otherwise, what else should I be looking at?

NOTE: I have yet to re-learn the ECU/IAC/TPS since getting it to start. Could this be the reason that it's not running right?

Thanks,

Darrin

[NutriaforBreakfast]

tried a new plug on cylinder 4?

[darrinos]

Hmmm....hadn't thought of the obvious. No....I have not. I'll give that a shot...start with least expensive issue first. Thanks!

[NutriaforBreakfast]

its a good rule of thumb if it makes sense
for that application
If that's not it try to multimeter the coil pack for resistance
Check it hot and cold (put in freezer and then check)
Also the crank pos sensor is in a place where lots of oil and water gets on it
i would clean it off while your down there

[darrinos]

Thank you about the crank pos sensor. I was headed that direction anyway since I also had to install a new harmonic balancer. Since the car was running well before the ECU/IAC replacement, I kind of doubt that I've developed a short in the harness while working on it. Just thinking out loud. I suspect the crankshaft pos sensor may well be suspect at this point. Thanks for the input. And just so everyone knows...there is another forum online...infiniti forum...those guys are worthless! Every time I post a question there, I get over 100 views, but NO ONE ever answers. Grrrr...