flashlight_65 Posted March 21, 2012 Report Share Posted March 21, 2012 My check engine light popped up as I was driving to work and started blinking when I drove uphill on my way home the other day so I went to O'Reillys to see what code popped up (P0308, misfire in cylinder #8.) Since the 'hoe has 119'000 miles and I dont know when the the last time the plugs or wires were changed. Before I did that I put seafoam through the vacuum line and in the tank. After I changed the plugs and wires (gapped the plugs to .040) the CEL went out, happily I drove around for a bit and it felt a bit smoother but still didn't "feel" right then BAM! CEL back on, so i took it back to O'Reillys and the same code showed up, so i swapped coil #8 with coil #4 and had it cleared out. After driving around again CEL came up again same code P0308. If it's not the plugs, wires or coil where should i look next? The fuel filter is a few months old but other than that im stuck. Any ideas? Vehicle: 2002 Chevy Tahoe LS 5.3 liter 4x4 My builds: my caddy my 'hoe friends impala Link to comment Share on other sites More sharing options...
h23a3lude Posted March 21, 2012 Report Share Posted March 21, 2012 My check engine light popped up as I was driving to work and started blinking when I drove uphill on my way home the other day so I went to O'Reillys to see what code popped up (P0308, misfire in cylinder #8.) Since the 'hoe has 119'000 miles and I dont know when the the last time the plugs or wires were changed. Before I did that I put seafoam through the vacuum line and in the tank. After I changed the plugs and wires (gapped the plugs to .040) the CEL went out, happily I drove around for a bit and it felt a bit smoother but still didn't "feel" right then BAM! CEL back on, so i took it back to O'Reillys and the same code showed up, so i swapped coil #8 with coil #4 and had it cleared out. After driving around again CEL came up again same code P0308. If it's not the plugs, wires or coil where should i look next? The fuel filter is a few months old but other than that im stuck. Any ideas? Vehicle: 2002 Chevy Tahoe LS 5.3 liter 4x4 Do you remember what brand the plugs were that you put in? 92 Honda Prelude SI H23a3 HU: Alpine CDA-105 Front Stage: DB Drive PT6.0 6.5" Rear Stage: Junk pioneers (Not sure what im wanting to do in the trunk, waiting) Speaker Amp: DB Drive A4 4200 Sub Amp: MB Quart DSC1500.1 Subs: 2 12" MB Quart Premiums Box: Slot port tuned to ~34hz Wiring: Kicker Ultraflex 0awg and Big 3 Alt: Stock (saving for a 200amp Excessive Amperage) Batteries: Optima Yellow Top and Stinger SPV44 Extra Equipment: Two Rockford Fosgate T2 12's (Recones in future) Kicker ZX1000.1 Selling: GOLF CLUBS- http://www.stevemead...03#entry1916603 Link to comment Share on other sites More sharing options...
jrchevy87 Posted March 21, 2012 Report Share Posted March 21, 2012 possibly a clogged injector. if you have access to a good scan tool and a fuel pressure tester then you can open each injector individually and note the pressure drop and if one drops less than the others then you know its clogged. have you ran a compression check on that cylinder and what was the condition of the plug you pulled out of that cylinder Jeep Wrangler TJ Hardtop Build Link to comment Share on other sites More sharing options...
h23a3lude Posted March 21, 2012 Report Share Posted March 21, 2012 the reason i ask that is because they said that sometimes running an NGK plug in those 5.3's will throw a code like that. Only run an Autolite or ACDelco plug. Also could be the intake gasket going bad.. GM's are know for their amazingly junky intake gaskets. 92 Honda Prelude SI H23a3 HU: Alpine CDA-105 Front Stage: DB Drive PT6.0 6.5" Rear Stage: Junk pioneers (Not sure what im wanting to do in the trunk, waiting) Speaker Amp: DB Drive A4 4200 Sub Amp: MB Quart DSC1500.1 Subs: 2 12" MB Quart Premiums Box: Slot port tuned to ~34hz Wiring: Kicker Ultraflex 0awg and Big 3 Alt: Stock (saving for a 200amp Excessive Amperage) Batteries: Optima Yellow Top and Stinger SPV44 Extra Equipment: Two Rockford Fosgate T2 12's (Recones in future) Kicker ZX1000.1 Selling: GOLF CLUBS- http://www.stevemead...03#entry1916603 Link to comment Share on other sites More sharing options...
jg23 Posted March 21, 2012 Report Share Posted March 21, 2012 another thing you can do to test the injector is use a noid light to see if its working right or check the resistance of the injectors to see if there all the same 2008 TahoeHU-PioneerMids/Highs amp- sundown 200.4Mids/Highs- hertz xls, hertz ml 700, audison voce tweetsAmp-2 AQ 3500sSubs-FI SP418sAlt-singer 350Big 3 1/0 Build Log UBL My YouTube channel Link to comment Share on other sites More sharing options...
jrchevy87 Posted March 21, 2012 Report Share Posted March 21, 2012 ngk's are typically bad in domestics. the only cars ive had good luck with ngk's is imports or cars that oil foul. another brand that i havent had good luck in domestics is bosch, honestly autolite and ac delco are the only good plugs for domestics Jeep Wrangler TJ Hardtop Build Link to comment Share on other sites More sharing options...
Bmike Posted March 21, 2012 Report Share Posted March 21, 2012 So heres a small list of the things that could be wrong, the only propblem is you will have to most likely have to reset after doing each one until your problem is solved. Start with the least expinsive and go from there. Causes A code P0308 may mean that one or more of the following has happened: Faulty spark plug or wire Faulty coil (pack) Faulty oxygen sensor(s) Faulty fuel injector Burned exhaust valve Faulty catalytic converter(s) Running out of fuel Poor compression Defective computer 2007 trailblazer lthead unit- pioneer p4300dvd crescendo ft-1 supertweeters pioneer m650 pros audiocontrol 2xs crossover Rockford fosgate p200-2 highsrockford fosgate p400-2 mids1- fi btl 18amps- saz 3500battery- evermax in front, 2 9a31 dekas in rearwires all knuconceptz 1/0 and rcas Link to comment Share on other sites More sharing options...
Keith77 Posted March 21, 2012 Report Share Posted March 21, 2012 Without seeing a scanner and looking at a data stream is damn near impossible to fix these newer cars over a thread. Your best bet is to sped the money on a diagnoses... Possible injector and also the intake gaskets are known to leak and suck a little air. FYI when the check engine light is flashing its not real safe to drive could damage other things... Oh don't forget the plug wire Thats cool. Im way too old to be upset by shit like that. Your name is winston. Your own parents hated you even before you were born. My penis is bigger than your penis I'm far from loud and my roof/headliner flaps around like Adam's ass on a windy day. I think it depends more on the structure of the vehicle. Link to comment Share on other sites More sharing options...
jrchevy87 Posted March 21, 2012 Report Share Posted March 21, 2012 another thing you can do to test the injector is use a noid light to see if its working right or check the resistance of the injectors to see if there all the same The noid light and resistance test is good for testing the electrical portion of an injector but for the mechanical part the only options are the pressure drop test and and physical inspection but pulling injectors on a whim is a pain in the ass, but good advice i forgot about it lol Jeep Wrangler TJ Hardtop Build Link to comment Share on other sites More sharing options...
Dwn4BassAlan Posted March 21, 2012 Report Share Posted March 21, 2012 I had something similar and my Gasket was bad, and they replaced it after I had the plugs done, so they missed it initially which could be what happened for you. Biomedical/Behavioral Science Major, The (Self-Proclaimed) Undisputed-Homemade-Woofer-King Super-Neodymium-Woofer Build Log: The D4BA-V.2 http://www.stevemeadedesigns.com/board/topic/169236-diy-super-neodymium-woofer-build-log/?p=2475620 Fucking love Alan you goddamned fucking super nerd lol When Alan uses big words I don't understand It's warming up enough that the donut-punching cyclist douchenozzles are getting their two wheeled fagmobiles out. Everytime I see a guy driving a mini cooper I cant help but think he loves cock & (2/29/16)-My wife just bitched at me about throwing out things we don't really use. My response of well we don't really use your vagina so should we throw that out was evidently not the right response. I had to leave the room. I missed Alan. RIP 5/29/15 - I love you son. Link to comment Share on other sites More sharing options...
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