'01 Chevy Tahoe P0300 Multiple misfire code

[saviola97]

So everything was fine. I turned on the car and ran perfect. I forgot a CD at home. Turned off the engine and then when i went back i turned it on and the trucks idle was extremely rough.
I pushed the gas and the RPM wouldnt go up, pushed again and it slowly went up but it started shaking bad, then it slowly was dying untill it died.

Right before it died the engline light went off. I scanned it and it gave me a code of p0300.

I changed the plugs and wires. Some plugs were a little oily, maybe it was gas (unsure).
Coils are fine, fuel compression is normal.

Im really going insane with this Truck, it has given me nothing but problems.

What should i do? Please help me!

[j cAT]

Originally Posted by saviola97

So everything was fine. I turned on the car and ran perfect. I forgot a CD at home. Turned off the engine and then when i went back i turned it on and the trucks idle was extremely rough.
I pushed the gas and the RPM wouldnt go up, pushed again and it slowly went up but it started shaking bad, then it slowly was dying untill it died.

Right before it died the engline light went off. I scanned it and it gave me a code of p0300.

I changed the plugs and wires. Some plugs were a little oily, maybe it was gas (unsure).
Coils are fine, fuel compression is normal.

Im really going insane with this Truck, it has given me nothing but problems.

What should i do? Please help me!

this is most likely a fuel pressure problem...measure with a pressure guage the fuel pressure ...the forum here has many posts describing in great detail this testing proceedure...

53-62 psi with the v8 engines is the spec.. completing the full testing will insure only defective parts are replaced ...

If it is the fuel pump defective use only the delphi pump. replace the fuel filter and fuel pump relay at this time ...make sure the frame rail ground next to tank is clean and secure as this is the pump ground point..

[saviola97]

I did, i checked the fuel pressure and it was a normal pressure. This is why im puzzled.
Changed coils, plugs (they were a little oily or dark black), checked the fuel pressure, battery.

I was told if you have an aftermarket alarm system in which i do, that it can damage a catylac converter. How can i test the converter? In addition i have to get rid of the alarm system as well.

[j cAT]

Originally Posted by saviola97

I did, i checked the fuel pressure and it was a normal pressure. This is why im puzzled.
Changed coils, plugs (they were a little oily or dark black), checked the fuel pressure, battery.

I was told if you have an aftermarket alarm system in which i do, that it can damage a catylac converter. How can i test the converter? In addition i have to get rid of the alarm system as well.

what was the pressure key on engine off ? how long did the pressure stay above the 53psi ..?

AFTERMARKET ALARMS and getting a dtc 300 does not compute.

with a defective componet in the fuel delivery or fuel control componets this cat converter failure is quite possible.

[saviola97]

Well all i did was pushed the fuel button and it just came out with a strong spray, all over the place.

Do you think since my plugs are a bit oily, that has something to do with it ?

[j cAT]

[quote=saviola97;6387721]Well all i did was pushed the fuel button and it just came out with a strong spray, all over the place.
[quote]

thats what I thought. If you are going to repair this you must follow the testing troubleshooting proceedures listed here at the forum...


asking questions then no testing and throwing parts at the problem is not good repair practice...

YOUR MONEY AND TIME !

[saviola97]

Alright im back.
So last night i went and bought a fuel pressure gauge. The pressure jump all the way to 60 psi and then it went down to around 52. I tested it twice to make sure and the same result.

So i got the spark plugs, wires, fuel pressure gauge, i took off the aftermarket alarm system and its still the same problem.

Any other ideas? Please help. Thanks.

[j cAT]

Originally Posted by saviola97

Alright im back.
So last night i went and bought a fuel pressure gauge. The pressure jump all the way to 60 psi and then it went down to around 52. I tested it twice to make sure and the same result.

So i got the spark plugs, wires, fuel pressure gauge, i took off the aftermarket alarm system and its still the same problem.

Any other ideas? Please help. Thanks.

you description of the fuel pressure does not explain what was going on when you indicate pressures..


ENGINE ON /RUNNING PRESSURE ?

KEY ON ,,,,ENGINE OFF PRESSURE AFTER 10 MIN ?

YES THIS IS PART OF THE PROCCEDURE ...IT DOES MAKE A DIFFERENCE...

[saviola97]

My truck wont turn on at all. Is there any other way to test it out ?

[j cAT]

Originally Posted by saviola97

My truck wont turn on at all. Is there any other way to test it out ?

turn on does not compute..

does the engine crank, but does not run ?

if so turn to ignition on do not crank and measure the fuel pressure , then see how long it stays above 53psi.


If the vehicle does not have power to crank , charge the battery with a charger at no more than 10amps..when fully charged do the fuel test.

[maxwedge]

Originally Posted by saviola97

My truck wont turn on at all. Is there any other way to test it out ?

Agreed, absolutely useless introductory info, it is getting somewhat tiresome! Plus a new thread should be started this is not a related issue to the op.

[saviola97]

Alright im back. So i got tired of diagnosing myself so i took it to my trustworthy mechanic. it turns out that someone urnitaed, poured coolant and salt in my fuel compartment...the plugs i bought brand new turned out oxidated in hours.

thanks for trying to help. I still owe 10k on my vehicle but im thinking of just having it repossed. what do you guys think?

[j cAT]

Originally Posted by saviola97

Alright im back. So i got tired of diagnosing myself so i took it to my trustworthy mechanic. it turns out that someone urnitaed, poured coolant and salt in my fuel compartment...the plugs i bought brand new turned out oxidated in hours.

thanks for trying to help. I still owe 10k on my vehicle but im thinking of just having it repossed. what do you guys think?

If you have it running now / tank , fuel system flushed out and filter/regulator replaced it should run...locking fuel cap installed ...

add marvel mystery oil 2-3 oz per tank full of fuel to clean out any other debris especially injectors ...

coolant in the cylinders from the fuel injectors is the bad thing .
if it is engine damaged and this is quite possible best park in e, la with the keys in it .