[Tom brayley]

Hello all members!looking for input on why my check engine light is flashing.just purchased this truck and keep hearing that i shouldnt be driving it.its an 02 silverado 1500hd with a 6 litre.any ideas?replaced exhaust manifolds..plugs and wires.was told the catalyst convertors may be plugged..so i gutted them.still flashing.scanner saying its running lean.and a random misfire.has a rough idle but smoother with higher rpms.any input would be appreciated!

 

[RayVoy]

The mis_fire is causing the flashing light.

Was the light flashing before you started to mod the truck?

 

[geo1]

The old 300 code,stinks,my 02 did it,changed plugs,wires, vacuum gauge for cats,all clear,ecm went stupid,took to dealership for crankshaft relearn procedure,my scan tool won't do it, problem solved, my wires and or plugs probably caused it

 

[j cat]

the fuel pressure must be measured should be above 52 psi.. if too low then pump / wiring problem.

next is the upper intake has gasket leaks. if the codes are both sides bank 1 and 2 this is common along with low fuel pressures.

if on a 2002 you have a specific cylinder the coils do fail.. plugs/wires not cause a 300 code random miss fire but a 306 code only would be a specific #6 cylinder issue plug/plug wire/coil/ valve/ etc..

 

[gusstarr97]

the fuel pressure must be measured should be above 52 psi.. if too low then pump / wiring problem.

next is the upper intake has gasket leaks. if the codes are both sides bank 1 and 2 this is common along with low fuel pressures.

if on a 2002 you have a specific cylinder the coils do fail.. plugs/wires not cause a 300 code random miss fire but a 306 code only would be a specific #6 cylinder issue plug/plug wire/coil/ valve/ etc..

I have a 97 5.7 vortec and it has a p0300 misfire code and I replaced plugs, wires, cap and rotor and cam shaft sensor from previous code, but I also have O2 sensor codes I have no cats and a the exhaust is in horrible condition( got it like that) could the horrible exhaust leaks and the o2 sensors going off cause a random misfire cause of the back pressure and sucking in to much air?

 

[j cat]

I have a 97 5.7 vortec and it has a p0300 misfire code and I replaced plugs, wires, cap and rotor and cam shaft sensor from previous code, but I also have O2 sensor codes I have no cats and a the exhaust is in horrible condition( got it like that) could the horrible exhaust leaks and the o2 sensors going off cause a random misfire cause of the back pressure and sucking in to much air?

on a 1997 350CU with more than 175K miles and original distributor then the distributor should be replaced as the rotor will wobble causing the 300 code. the exhaust leaks must be fixed as this will throw the PCM into confusion as the O2 sensors will report bad data...

 

[gusstarr97]

on a 1997 350CU with more than 175K miles and original distributor then the distributor should be replaced as the rotor will wobble causing the 300 code. the exhaust leaks must be fixed as this will throw the PCM into confusion as the O2 sensors will report bad data...

Alright thanks what do you recommend on a distributor?

 

[HeavyChevyz71]

The old 300 code,stinks,my 02 did it,changed plugs,wires, vacuum gauge for cats,all clear,ecm went stupid,took to dealership for crankshaft relearn procedure,my scan tool won't do it, problem solved, my wires and or plugs probably caused it

Hey geo1. I was hoping you could help me out to better understand if doing what you did by having the dealer reset the crankshaft would also help me. I have a 2000 chevy silverado z71 that feels and sounds like it has plugged cats and idles really rough like it wants to die. But i wanted to start off small and then work my way up to the cats as well as the intake manifold gaskets if need be. I started somewhat of a tune up by replacing the sparks and wires october of last year with no luck. I still have a flashing check engine light and a rough idle on cold or hot start. Should i take it straight to my local dealer and have them relearn the crankshaft as you did? Or should i start with fuel injectors and o2sensors? Any advice is greatly appreciated please.

(On a side note after replacing the plugs and wires i havent touched the truck since as it has been sitting all winter. Im just now getting back into trying to fix it. But i did attempt to start my truck in january to see if anything might have fixed itself lol but to no avail. It still idles rough with the flashing light.)

 

[geo1]

I think for o.p.,I was trying to push for a proper diagnosis,300 can be frustrating,you could test fuel pressure, spray some throttle body cleaner at intake ports,listen for rpm change,and a throttle blip test with vacuum gauge hooked up for cat check

 

[geo1]

Forgot to mention,with my truck,I had no drivability problems, nothing,just a lite at 70 mph,and I could have had it for a long time,I don't go that fast, but I did on a road trip, truck was telling me to obey speed limit,lol

 

[HeavyChevyz71]

Obey the trucks we must and maybe some laws lol
Will do geo thanks for the ideas and swift response. Very much appreciated!

 

[danny123162]

Took 2007 Canyon 3700 vortec 5 cylinder to dealer.Started running rough check engine lite flashes.Was told it needs a motor.They said back cylinder had half the compression.Not sure I believe them.They also said it needs a tune-up and a bad coil.It runs rough but above 1500 rpms motor smooths out...Need some advice love the truck.

Danny

 

[RayVoy]

It probably needs a coil.

If you have an OBD2 reader get the code(s), if you don't, take it to a parts store, they will read it for free, hoping to sell parts. Let us know what the codes are.

Did it rain in the days before the problem occured?

If it did, you may be getting rain water on to of the engine.
If you are, the water flows into one of the coil holes on top of the engine (I don't remember which one, maybe #4)
You can tell by removing the coil packs and looking for water, or rust.

If your having this problem, let us know