I just replaced my battery and my car has thrown the so called dreaded P0300 Random/Multiple Cylinder Misfire. Silver Star (my Bonnevilles name) has been sitting since January due to a dead battery. The battery was taken out and the car sat there with no battery. Just cleaned/replaced my throttle body and installed a new battery. I erased the code and the car seems to be acting normal . New spark plugs will be put in this friday. Was this a random code?

Also will the vacuum t-fitting (connector) on the lower throttle body vacuum line cause this code if it was cracked all the way through?

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1997 Bonneville SLE...(SilverStreak)...Totaled...1/25/13...Gone but not forgotten.
1992 K5 Blazer...(Grayson)(Big Bertha)...4x4...383 SBC...500 hp...more mods to come

If the battery was disconnected for months, there shouldn't be any codes stored in the history.

I'm assuming you drove the car for a short time to get that code. Did you notice the CEL flashing while driving? Was the car sputtering?

If you erased the code, it won't come back again until it misfires.

Common problems that can create a misfire: spark plugs, plug wires, ICM, coils.

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-Andrew-

2004 Bonneville GXP | White Gold Tricoat | 144k | His
2000 Bonneville SSEi | Light Bronzemist Metallic | 152k | Hers
2005 Town & Country Limited | Butane Blue Metallic | 191k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 144k | Official Bonneville Hauler

I didn't drive it at all. i would jump it once every week to get the fluids going and thats it. the car was previously parked due to the fact that it was driven around 100 miles with only 3 qts of oil in it (to fix oil leak due to valve cover gaskets). The only noticibly sound that is visible when i start it is the lifter tick but that is it.

Could that cracked vacuum t-connector have anything to do with this also?

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1997 Bonneville SLE...(SilverStreak)...Totaled...1/25/13...Gone but not forgotten.
1992 K5 Blazer...(Grayson)(Big Bertha)...4x4...383 SBC...500 hp...more mods to come

Oh and i forgot to mention that the CEL does not blink...it staus on solid. When i first start the car the tach jumps a little bit but settles shortly at 1000-1100 rpm. I thought that was a little high but my scan tool shows my rpm at 875-950 rpm.

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1997 Bonneville SLE...(SilverStreak)...Totaled...1/25/13...Gone but not forgotten.
1992 K5 Blazer...(Grayson)(Big Bertha)...4x4...383 SBC...500 hp...more mods to come

The CEL will only blink if the misfire is happening at that instant.

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2003 SSEi

All i know is that the CEL stayed on and did not blink. I erased the code and let the car run for 10 minutes and it didn't no come back

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1997 Bonneville SLE...(SilverStreak)...Totaled...1/25/13...Gone but not forgotten.
1992 K5 Blazer...(Grayson)(Big Bertha)...4x4...383 SBC...500 hp...more mods to come

i would not worrie if it does not happen again .

a vacum leak will not cause a misfire . i will cause high idle and lean condtions .

you said you cleaned the throotle body and or replaced it ? you mean you pulled it off to clean it ?

if so make sure everything was put back right . and recheck the tps sensor and make sure you installed it the right way . there is a video in tech info on the tps sensor

A vacuum leak CAN cause misfires. If the mixture is too lean, it will not ignite. Fix the vacuum leak.

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It could have been a small misfire due to sitting for a while, who knows. Fix your vac leak and keep an eye on it, but don't worry too much.

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2003 SSEi

I bought a throttle body from a junkyard due to mine having a cracked plate. I cleaned the new one and put it on.

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1997 Bonneville SLE...(SilverStreak)...Totaled...1/25/13...Gone but not forgotten.
1992 K5 Blazer...(Grayson)(Big Bertha)...4x4...383 SBC...500 hp...more mods to come

I fixed the vacuum leak and the code has not come on while it has been driven. Every now and then when i crank the engine over the code will return. I was told that this is an ignition misfire that can be fixed by changing plugs, wires, coils, and ecm. Does this sound correct to you?

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1997 Bonneville SLE...(SilverStreak)...Totaled...1/25/13...Gone but not forgotten.
1992 K5 Blazer...(Grayson)(Big Bertha)...4x4...383 SBC...500 hp...more mods to come

it would be a good idea to replace the plugs and wires if you just bought the car and dont know when the last time they have been done.

now for the ICM ? is this what you meant ? this is not cheap and would have it checked first . many part stores will bench test it for you .