Ive really been trying to come in here and ask for help with my 99 yukon (4x4). Just been with out internet for a few months. Any ways, my Yukon resently started not starting correctly. When i go to start it in the morning (or when ever engine has been sitting for a few minutes) it makes a really bad knock sound, like if u hit a metal post with a bat. Then i try it again and it sounds like it wants to start but dosnt. On the third try i hold the key on the start position and i get a really slow engine start. Any tips? Also just got a code p0430 (lots of white smoke when engine is warming up). Check engine light always seams to turn on when its almost smog check time. Any tips on that? Thanks for taking the time to read.
Need help with a p0430 code and a really bad start.
- Thread starter 99yukon99
- Start date
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SunlitComet
OBS Jedi-Do Good
p0430 means the right cylinder bank cat converter is chemically bad. if knocking and white smoke then it will definitely do that to a cat. before doing anything elsecan you inspect your plugs and get some pics up and maybe get a compression test done. i am pretty sure you have a bad cylinder leaking oil or coolant into it self. it may even be hydro-locking?
In the beginning, it had a p0340, cylinder 4 misfire. I replaced all the sparkplugs. Did notice that cylinder 4's was really beat up. Unfortunately i disposed of the sparkplugs(no picture for that) but i will remove and inspect the new ones.. The knocking actually is coming from the engine, when i try to start it.. Thanks for your reply. I will try and be more specific and try to post pictures for better insite.
SunlitComet
OBS Jedi-Do Good
see if you have p0338 stored and any of thew following:
^ Backfire during crank/start ^ "Kickback" during crank/start ^ "No" start ^ "Slow" or "hard" start/crank ^ "Grinding" or unusual noises during crank/start ^ Cracked or broken engine block at the starter boss ^ Broken starter drive housing ^ Broken starter ring gear on flywheel ^ Any combination of the above
^ Backfire during crank/start ^ "Kickback" during crank/start ^ "No" start ^ "Slow" or "hard" start/crank ^ "Grinding" or unusual noises during crank/start ^ Cracked or broken engine block at the starter boss ^ Broken starter drive housing ^ Broken starter ring gear on flywheel ^ Any combination of the above
Sorry for the late reply. I took some pictures of the codes the scanner was reading. Dont know how to post them on here.. Codes are P0430 catalyst system efficiency below threshold bank 2, P0300 multiple misfire, i already replaced the spark plug wires. I also have pictures of the system test. "sec air systm N/A.. Ac refrig Mon N/A.. Htd catalyst N/A.. I used Actron Auto scanner. Small orange one.. Again sorry for the late replies dont have constant internet access.
SunlitComet
OBS Jedi-Do Good
use "go advanced" button below dialog box. and use the icon that looks like a paper clip. it will open another window that will allow you to browse and upload pics from your computer.
---------- Post added at 12:50 PM ---------- Previous post was at 12:47 PM ----------
i am gonna hazard to guess but if all misfires are from cylinders 2, 4, 6 and 8 i say you got a clogged cat. if you can get a misfire history that would be great. also what do you know of current condition of dizzy cap?
---------- Post added at 12:50 PM ---------- Previous post was at 12:47 PM ----------
i am gonna hazard to guess but if all misfires are from cylinders 2, 4, 6 and 8 i say you got a clogged cat. if you can get a misfire history that would be great. also what do you know of current condition of dizzy cap?
I apologies for the long delay on my replies. I use my friends smart phone to log in when i get a chance. He logged in for me last week and told me about your tip about the distributor cap. I replaced it and that fixed the random misfire code. 
at least so far. Thank you so much for that one. I cant believe i missed that. Next, im going to replace the catalytic converter. Hopefully that takes care of the other code. I did see water dripping from the exhaust. Dont know if thats cause of a bad cat.. Thanks again for the really helpful tips.
at least so far. Thank you so much for that one. I cant believe i missed that. Next, im going to replace the catalytic converter. Hopefully that takes care of the other code. I did see water dripping from the exhaust. Dont know if thats cause of a bad cat.. Thanks again for the really helpful tips.
SunlitComet
OBS Jedi-Do Good
water coming out can be a few different things some ok some not. if you live outside of california: http://www.amazon.com/Magnaflow-23453-Catalytic-Converter-compliant/dp/B000JKNGY8/
