slap(A)hoe

iTrader: (2)

I got a 98 z28 I just put a new motor n it everything on the motor is brandnew I keep getting a p0300 code I replaced the plugs ngk tr6 in it now I put 2 brand new o2 sensors in it I have cleared the code it comes back after driving it around I've checked all the grounds I have checked all the fuses I've checked for vacuum leaks and I've cleaned the mass air with the proper cleaner for it but noting works. I have checked for broken valve springs I done a compression test all was good and the car has been tuned here are the symptoms I am having.

When it first cranks its hunting idle.

I smell fuel like its running rich but plugs look good

If I get on it just a little it will cut off and ut want crank back up if I don't give ut a little pat at the gas pedal

It don't have a skip that I can tell I am lost on what else to change unless I start changing sensors so what do u guys think any help is appreciated

Frost

iTrader: (45)

The car is telling you it's misfiring and you are describing symptoms of an ongoing misfire. This isn't a tuning issue, just maintenance.

Start with checking plugs and wires and go from there.

Frost

iTrader: (45)

Also FWIW, the PCM is a little stupid here... On one hand it 'knows' it's misfiring. On the other, the front O2s see the fresh air from the misfiring cylinder and misinterpret that as being lean. This causes the PCM to PILE on fuel to that side (or sides) of the motor that has the issue as it tries to correct what it sees as being lean. This will foul plugs (or worse if run this way an extended amount) and can hurt cats if they are on the car.

slap(A)hoe

iTrader: (2)

I have changed the plugs and bought taylor wires for it and it don't have cats on it everything is brandnew on this car with less than 200 miles on everything

Frost

iTrader: (45)

if it's got a healthy cam, it can report false misfires, but you are describing actual misfires.

Buffalo

I'm pretty sure that this is what is wrong with my car. How would I fix this? Sorry to steal the thread.

Frost

iTrader: (45)

fix the misfire and the fueling issue will go away.

slap(A)hoe

iTrader: (2)

no problemmaybe we can figure them both out lol!! my cam is 228/232 595/608 cut on a 115 lsa

would cam or crank position sensor cause anyof these issues or maybe a bad mass air meter ???

vette0009

O2 Wire harnesses aren't crossed

Also did you cut those Taylor wires to length ?

Or did they come custom prefit

Also check the wire harness for any damage

slap(A)hoe

iTrader: (2)

I went out n front if my shop this afternoon and held the brake and done like a 3000 rpm burnout and under a load u can gear the car breaking up im just wandering if maybe my coil packs are going bad? ?

slap(A)hoe

iTrader: (2)

i just replaced the iac sensor to see if it makes a differece the one that was on the car was real wobbly and it wouldnt spring back into place like the new one so im gonna see and i also took the neg cableoff the battery to clear anything that may be in the computer i was told that would work hope i get this figured out soon it getting nerve racking

Matt@SNLPerformance

iTrader: (1)

How does your reluctor wheel look?

slap(A)hoe

iTrader: (2)

it looked good when i put the oil pan on

lt1pwr1

iTrader: (1)

Have you done a crank relearn procedure with a scanner?