Code P0300 (and P1516)

[ANGRY6LITER]

Doesnt make a whole lot of sense to me so Im here to ask and hopefully you guys have already figured this one out. Keep in mind my truck was running perfect and never threw any codes, until..............

I had a Factory throttle body and Factory alternator and upgraded them. I installed the BBK 80mm thottle body and a chrome 180 Amp alternator. After initial startup and everytime I drove the truck I was getting P0300 (Random/Multiple cylinder misfire detected) and P1516 (TPS sensor out of range). If I got on the gas hard it went into Reduced Engine Performance mode. After talking with BBK several times (noting that the ETC motor came out in two pieces when I removed it from the Stock throttle body, but put it back together correctly with spring properly on motor shaft) I put the TPS sensor cover and ETC motor back in the Stock throttle body and reinstalled it to see what it did. It got rid of the P1516 code but the P0300 stayed. I then replaced all NGK Iridium IX plugs (gapped at .040"), replaced 2 of my Taylor 10.4 wires that looked toasted, put more header wrap on hot spots and still that damn P0300 code. It runs pretty strong and doesnt seem to truly be misfiring but the SES flashes and keeps throwing the P0300 code. Also keep in mind I just put on MSD coils about 1,000 miles ago so I would rule out coils, plus I HAD NO PROBLEMS before Throttle body & Alternator swap. Im blaming the Throttle body parts and am buying a new GM Throttle body tomorrow so I have a new ETC motor and TPS sensor to install. Its weird to me that the mechanical BBK throttle body could be the cause unless it is closing too far, but I checked it by hand and it doesnt stick. Anyone got any advice on how to fix the issue/why and what the cause is/know any tricks on the BBK 80mm installation? Thanks in advance.

Edited March 22, 2009 by ANGRY6LITER (see edit history)

[Barney]

It has been my experience that the bbk's dont work. I tried one also then I just ported my throttlebody and made a new butterfly. Its much better! And no codes.

[ANGRY6LITER]

OK, so im about at the end of my wits with this thing. I tried a NEW Factory throttle body($270), still throwing

P0300 code. I put the old Factory throttle body back on. I checked ALL the fuses interior and engine block. They are all good. Cant figure out what the hell happened. Im still messing with it, but looks like Im taking it to the dealership tomorrow morning.

Edited March 23, 2009 by ANGRY6LITER (see edit history)

[ANGRY6LITER]

This sh!t makes NO sense to me, but here was the fix/outcome. The dealership visit revealed that #3 and #5 cylinder coil packs were bad. So we replaced them with Borg/Warner replacements ($35 each at PepBoys) and the truck ran like a champ again and all codes were gone. $144 paid to the dealership. (Summit Racing is exchanging my 2 bad MSD coils for 2 new ones, as they should) I drove it around awhile and after I was satisfied she was good I brought it home. Not liking the fact that it makes no sense that the BBK throttle body didnt work, I decided to try it again. Mechanically they are the SAME with the exception of the larger bore. I carefully transplanted my factory ETC and TP sensor/cover to the BBK, noting that the Factory throttle body and the cover have about a 1/8" gap between them. Originally when I installed the cover I was cranking it down flush with the 4 screws. I assume this was making the TPS bind and causing the P1516 code. But now with the new 80mm BBK throttle body it idles good, there are NO codes and IT RUNS LIKE A SCALDED DOG!