Need help with a 2002 chevy silverado.4.3 random cylinder misfire

[Guillot]

ok i have a 2002 chevy silverado with a 4.3 in it. I got a code for a bad cam and crank senor. So i replaced them and now the check engine light is still on so i took it to get it checked out and now they tell me that i have a random cylinder misfire now. So i go and replace spark plugs,wires,cap and button. Well its still skipping it does it when i push the gas a little or when i am at a taking off from a red light or riding down the hwy steady it skips bad. Now does anybody know anything about this problem?

Thanks
Mike

[danielsatur]

I would start with a MAF sensor, up-stream 02 sensors, and a good throttle body cleaning.
Is there any DTC's?

[j cAT]

Originally Posted by Guillot

ok i have a 2002 chevy silverado with a 4.3 in it. I got a code for a bad cam and crank senor. So i replaced them and now the check engine light is still on so i took it to get it checked out and now they tell me that i have a random cylinder misfire now. So i go and replace spark plugs,wires,cap and button. Well its still skipping it does it when i push the gas a little or when i am at a taking off from a red light or riding down the hwy steady it skips bad. Now does anybody know anything about this problem? oh yea it has 125000 on it

Thanks
Mike

step 1: measure fuel pressure...random miss fire is usually the fuel pressure...

So what eactly is the DTC'S pulled ? this would be more helpful...
a bad crank/cam sensor. what DTC'S were pulled with that issue ?

[Guillot]

Originally Posted by danielsatur

I would start with a MAF sensor, up-stream 02 sensors, and a good throttle body cleaning.
Is there any DTC's?

MAF is new all so sorry i have cleaned the throttle body.

[Guillot]

Originally Posted by j cAT

step 1: measure fuel pressure...random miss fire is usually the fuel pressure...

So what eactly is the DTC'S pulled ? this would be more helpful...
a bad crank/cam sensor. what DTC'S were pulled with that issue ?

Ok i new i was going to get asked this.lol sorry the first time that i got the code i did not get the # they just told me that i needed a crank/cam sensor and that was it. Then check engine light went off. Then 4 hours later it comes back on and runs rough and some times it will go off and stay off fort about a 1hr or 2 and then come back on and stay on for days or sometimes 1 day and goes back off but it pulls a P0300 code every time?

[danielsatur]

Are you sure it's random misfires, I did a ''In the car Injector service'' , some clown had extra injector seals forced into the fuel rails.

Is your Throttle body a drive-by-wire system?

[Guillot]

Originally Posted by danielsatur

Are you sure it's random misfires, I did a ''In the car Injector service'' , some clown had extra injector seals forced into the fuel rails.

yea i am sure thats what the computer said i have had the truck for about 6 weeks and it has just started doing it.

What do you mean bye is my Throttle body a drive-by-wire system?

[danielsatur]

The drive-by-wire system, the accelerator pedal is electronic control, not cable driven.
The throttle body has a electronic control for the throttle plate, it can get stickey and cause random misfires.

[Guillot]

Originally Posted by danielsatur

The drive-by-wire system, the accelerator pedal is a electronic control, not cable driven.
The throttle body has a electronic control for the throttle plate.

oh sorry yea it is the drive-by-wire system it does have a cable

[danielsatur]

Actually, I have seen cable driven throttle bodies lost hp, because of a stickey throttle plate.

http://www.automotiveforums.com/vbul...d.php?t=949299

Poor emissions during two drive cycles!

125k miles on this truck, you did the plugs, MAF, and throttle body cleaning.

Opps!

What about the up-stream 02 sensors?

[Guillot]

Originally Posted by danielsatur

Actually, I have seen cable driven throttle bodies lost hp, because of a stickey throttle plate.

http://www.automotiveforums.com/vbul...d.php?t=949299

I will check that out but i just dont think that is it. But you never know i have tried almost everything else.

[j cAT]

Originally Posted by Guillot

I will check that out but i just dont think that is it. But you never know i have tried almost everything else.

fuel pressure fuel, pressure fuel , pressure fuel pressure, and fuel pressure..............step 1....

It is your vehicle though so if you like to spend some money with no results go for it.

[Guillot]

Originally Posted by j cAT

fuel pressure fuel, pressure fuel , pressure fuel pressure, and fuel pressure..............step 1....

It is your vehicle though so if you like to spend some money with no results go for it.

thats what some one else has said that it might be the spider injectors on my truck?

[kahjdh]

Did you do a cam/crank sync after you put it the new sensors?

[curtis73]

This is what I would check (in this order)

Coil, rotor, vacuum leak between the MAF and TB, compression test.