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

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

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

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 ?

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.

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?:swear:

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?

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?

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.

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

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

http://www.automotiveforums.com/vbulletin/showthread.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?

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

http://www.automotiveforums.com/vbulletin/showthread.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.

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.

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?

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

This is what I would check (in this order)

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

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

no i did not know u had to or how to?

I think you need a tech 2 but with the older 4.3's, (havent had to do a newer one), You would put the computer into learning mode, hold the engine at the rev limiter for approx 10 secs and let off and the computer recalibrates. I have done this alot with astros and blazers but never with a full size so I dont know.

Probably a coil.

My bet is on a worn out timing chain.

I think you need a tech 2 but with the older 4.3's, (havent had to do a newer one), You would put the computer into learning mode, hold the engine at the rev limiter for approx 10 secs and let off and the computer recalibrates. I have done this alot with astros and blazers but never with a full size so I dont know.

I will check on that and see?

ok i have to ask i do not have anything to check the fuel pressure but i did take the two rails out of the spider and i need to know if when u turn the key on does the gas come out like fast with a steady stream or does it come out half steam? i put a set of used spider injectors in the truck and it made the truck run worse so thats why i am asking?

Thanks
Mike:banghead:

Update!!!! i have got everything checked on the truck today and i was told that the distributor or the computer was bad? The fuel pressure is good.

Update!!!! i have got everything checked on the truck today and i was told that the distributor or the computer was bad? The fuel pressure is good.

since you give no specifics , this posting of your issue is going no where.
this is a waste of time.

since you give no specifics , this posting of your issue is going no where.
this is a waste of time.

here u go this is what i have found!!!! Now is it a waste of time?


Here's the bullitin. Bulliting #03-06-04-041 published on 08/26/2003.

-------------------------
Poor Engine Performance - Misfire, Rough Idle, Service Engine Soon/Check Engine Light Illuminated, DTC P0300 Set (Inspect DIstributor Ignition (DI) System Components and Replace As Necessary) #03-06-04-041 - (08/26/2003)
Poor Engine Performance -- Misfire, Rough Idle, Service Engine Soon/Check Engine Light Illuminated, DTC P0300 Set (Inspect Distributor Ignition (DI) System Components and Replace As Necessary)
2001-2003 Chevrolet Astro, Blazer, Express, S-10, Silverado

2001-2003 GMC Jimmy, Safari, Savana, Sierra, Sonoma

2001 Oldsmobile Bravada

with 4.3L, 5.0L or 5.7L Gas Engine (VINs W, X, M, R -- RPOs L35, LU3, L30, L31)

Condition
Some customers may comment on poor engine performance and the Service Engine Soon/Check Engine light being illuminated. Upon investigation, the technician may find DTC P0300 set.

Cause
This condition may be due to high levels of internal corrosion in the distributor, causing spark to go to the wrong cylinder. This corrosion is attributed to a lack of air flow internal to the cap caused by the EIP screens being clogged with debris.

Correction
Inspect the internal components of the Distributor Ignition System using the procedure listed below. A new distributor base has been released for service with improved airflow screens.

Inspect the distributor cap. You may notice a white residue on the cap walls. For higher mileage occurrences, the interior of the cap may have changed to medium brown in color.
Inspect the distributor rotor. You may notice the presence of black streaks on the plastic surface. More typical evidence would be visible green spots on the copper surface of the rotor segment.
Inspect the distributor base. You may notice high levels of surface rust on the distributor shaft or surface contamination on the sensor hold down screws.
Inspect the distributor EIP screen. The screens should be free of any debris and the mesh should be visibly porous.
All of these inspection can be done on-vehicle. If there is evidence of this internal corrosion, replace the affected component. Refer to the appropriate procedure in the Engine Controls sub-section of the applicable Service Manual.

In addition, it has been determined on the Sierra and Silverado applications with the 4.3L engine that the A/C accumulator line is routed directly above the distributor area and condensation from that line can aggravate the corrosion condition. For these vehicles, install the foam sleeve, P/N 15190971, to the A/C line. Cut a slit in the sleeve and secure to the line using tie-straps.

Parts Information
Part Number
Description

10452458
Cap, Distributor (V6)

10452457
Rotor, Distributor (V6 and V8)

93441559
Distributor (V6)

10452459
Cap, Distributor (V8)

93441558
Distributor (V8)

15190971
Foam Sleeve


Parts are currently available from GMSPO.

are you serious ! what does some generic tsb have to do with specific data that is about YOUR VEHICLE ?

you have yet to give specific info about your vehicle...

yes indeed until you do this is going nowhere..

it appears you are not the person actually doing the work and therefore can not give this info...

you must then suffer the guesses of the persons repairing your vehicle..

are you serious ! what does some generic tsb have to do with specific data that is about YOUR VEHICLE ?

you have yet to give specific info about your vehicle...

yes indeed until you do this is going nowhere..

it appears you are not the person actually doing the work and therefore can not give this info...

you must then suffer the guesses of the persons repairing your vehicle..


I replaced it and the truck runs great like new. I took it to dealer to put it on the computer and they told me what was wrong with the truck(cost me 100.00 bucks) and they replaced the Foam Sleeve that causes the problem. So i went out and bought a new distributor and installed it today.

Thanks to everybody that has helped me with this. I do like the site i have been reading up on things so that i will know from now on and have told people about the site and maybe that it will help them also.

I replaced it and the truck runs great like new. I took it to dealer to put it on the computer and they told me what was wrong with the truck(cost me 100.00 bucks) and they replaced the Foam Sleeve that causes the problem. So i went out and bought a new distributor and installed it today.

Thanks to everybody that has helped me with this. I do like the site i have been reading up on things so that i will know from now on and have told people about the site and maybe that it will help them also.


I still can't believe you ! what was changed ? what did they find defective ? this is b/s !

I still can't believe you ! what was changed ? what did they find defective ? this is b/s !


what is your problem?:screwy: I had everything check the fuel pressure,pump,injectors,plugs,wires,cap..... I went and checked the site to see other post on here and checked what people on here have done.That is what the site is for right?Sorry u did not get to figure it out.I know that i am new to this site but i do read and i do listen. Yes i did do it myself i even went and replaced the injectors with new MFI Assembly so that i would not have to do it later instead of the old that leaks all the time.

I have a miss fire on my number four but my truck is runnin just like in ur first post.. so the foam sleeve is what fixed it or the distributor??? bc i have changed my rotor cap and button maf sensor plugs and wires.. so what did the foam sleeve go to?? i haven't done my distributor yet.. should i???

I have a miss fire on my number four but my truck is runnin just like in ur first post.. so the foam sleeve is what fixed it or the distributor??? bc i have changed my rotor cap and button maf sensor plugs and wires.. so what did the foam sleeve go to?? i haven't done my distributor yet.. should i???

an issue has been discovered that causes water dripping on the distributor . the AC line requires a foam insulator to prevent condensation from damaging the distributor/etc components.

the forum member never did say what this foam sleeve was for ..just it fixed it .

water dripping on your distributor will require new parts to repair then the foam to prevent a repeat failure.

Tell you what boys I farted around with my 4.3L for a week off and on with a #4 misfire and after checking many things out I found the distributor drive gear was worn.