Need some help. I have a 2002 Chevy Impala V6 3.8L car. Changed my cylinder heads, had them resurfaced and pressure tested and valve all re done. all new gaskets, and new plenum and map sensor, new plugs and wires. now I'm getting code P0303 cylinder 3 misfire and P1106 map sensor high low voltage. Not sure if i should change the ignition coil here. I was also wondering if there was anyway to externally check timing marks on this engine, 3800 series II. any help would be greatly appreciated. Thanks.

Mike

 

so i couldn't figure it out, so schanged crankshaft sensor, ignition coil and fuel injector, now the mis fire has been taken care of. but it sounds as if my timing is off. I still need to get a case relearn done. does anybody think that after my case relearn has be done my timing may be better. or is there another issue i should be addressing?

 

I had a cylinder 4 misfile on my 2002 Tahoe. Changing plug on # 4 did not help. I swapped the coil and wire with #6 and no change. Fearing the worst I sat down to think about it, and realized that in the days with a carburetor all cylinders are fed off of the carb at the same time. In this case, each cylinder has it's own fuel injector to feed that cylinder. If the fuel injector for a particular cylinder isn't letting out fuel AT THE PROPER TIME for when the intake valve opens, then you are going to get a misfire on that cylinder because it is not getting fuel. In my case I replaced the injector for #4 and the misfire messages stopped.

 

got my car running a lot better now...then all of a sudden my cel comes on....plug in the scanner....now i have p0172, p1133, and p1189....172 is system to rich bank 1, 1133 h02s 1/1 insufficient switching, and 1189 engine oil pressure ckt...any ideas how i should attack this...was gonna replace upstream 02 sensor to try an address the 1st too...but p1189....i have no idea what i should do....please help

 

If you were to record all the codes you have, then clear them and see what comes back. Is is possible some of the codes you have a residual from the previous failures? My 2001 Impala got a catalytic efficiency error and a rich bank error when the ignition module went bad causing a misfire on 2 cylinders. Clearing the code got rid of the misfire and rich error codes but the cat efficiency kept coming back every time it rained or snowed. While the service manual said to replace the cat, I figured maybe the sensor that's telling the system the cat is not good went bad. Replacing the O2 sensor cleared up all remaining codes.

 

grabbed some random parts from the bone yard to plug n play before purchasing new parts...o2 sensor checked out ok...but still figured its about time to replace it...changed my throttle body screen...old one was pretty banged up...and threw in a fuel pressure regulator....think that did the trick...still waiting for it to throw a cel to see if there is something else...but seems to be running a lot better so far

 

Excellent - keep your fingers crossed!

 

Is that the MAF screen? Sorry, I don't know the 3.8L v6.

I removed the honeycomb MAF screen on my LT1 f-body.