Troubleshooting Need Help

[Tahoe_96]

So a couple weeks ago I got a CEL and the code was P0300. And after being on this forum a little while now I instanly assumed thats it needed the upgraded MPFI. So I bought the new spider and installed it and I still have the misfire.

So now I assume I need to check the plugs and wires....what else could cause this issue?

 

[SunlitComet]

possibilities are damaged ignition components, leaking egr valve, leaking intake gaskets, dizzy misalignment, sticky valves or low cylinder compression. what kind of scanner you got can it look at misfire history. that would be a big diagnosis plus.

 

[Tahoe_96]

possibilities are damaged ignition components, leaking egr valve, leaking intake gaskets, dizzy misalignment, sticky valves or low cylinder compression. what kind of scanner you got can it look at misfire history. that would be a big diagnosis plus.

i dny have a scanner i just stop by autozone when i the CEL comes on...well i do know that the lower intake gasket was replaced about a year ago and I replaced plenum gasket when I put the MPFI in...I use to get a code for the EGR but I cleaned it and replaced its gasket few months ago....what kind of scanner would I need to see those things

 

[SunlitComet]

Any scanner that can read cylinder misfire history can narrow down which cylinders are acting up. If you have to, hit up a local shop with an OTC or snap-on scanner or buy a good one somewhere. I use a laptop based scanner system. My interface and software cost me $ 290 but there are others out there. Try scantool.net

 

[Tahoe_96]

So today I paid $40 to have a SnapOn scanner plugged into my Tahoe and I had two codes P0300 and P0155. The history only showed the P0300 code. After we cleared the codes the P0300 came back within a few minutes and the P0155 did not atleast not within the 30min that I was there. So I'm still confused.

 

[sparg93]

did you do any work in the engine bay (i.e. tune-up, moving wires, etc) prior to the code popping up??

 

[SunlitComet]

You need to look at cylinder misfire history. The pcm keeps a running tab on which cylinders are misfiring and how many times. Not just a 0300 code that means random cylinders. The misfire history will point out the specific cylinders themselves.

---------- Post added at 06:32 PM ---------- Previous post was at 06:27 PM ----------

as far as the 155 code it is pointing out that there is a heater problem on the forward o2 sensor for right cylinder bank. and being how it is the front one can be related to having misfires. check the wire connections for that sensor for proper connection and no damage.

 

[Tahoe_96]

You need to look at cylinder misfire history. The pcm keeps a running tab on which cylinders are misfiring and how many times. Not just a 0300 code that means random cylinders. The misfire history will point out the specific cylinders themselves.

---------- Post added at 06:32 PM ---------- Previous post was at 06:27 PM ----------

as far as the 155 code it is pointing out that there is a heater problem on the forward o2 sensor for right cylinder bank. and being how it is the front one can be related to having misfires. check the wire connections for that sensor for proper connection and no damage.

The guy running the scanner told me that was the only history he could pull up. He may not have known what he was doing.... o2 sensor could cause misfire guess ill have to check prices on those

 

[SunlitComet]

find another scanner place to go to. and ask before you pay them. and actually the misfire can f*** the o2 unit.

 

[Tahoe_96]

I have some time this weekend to pull a few thing apart on it....how can I tell if the Distributor cap, rotor,and other components are in good working order