Ok, I am having an intermittent p0300,code on my 2012 Denali. You can feel and see on the tach a random,mis at idle and anything below around 1500 rpm. I recently installed a cai, long tube headers with catless y and had a black bear tune. I replace my plugs and wires when I did the headers. I have cleaned the maf and looked for obvious vacuum leaks to no avail. I never got the code prior to installing headers, but I also only had the truck for two weeks,before I installed them! I am,looking for some ideas on where to look next?
P0300
- Thread starter jjaymoore
- Start date
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anytime I have had trouble like that myself it was always coil packs, but what brand of plug wires did you use?, if you still have the old ones maybe try putting those back on temporarily to see if the problem goes away
I used Taylor wires. I may throw the old wires on tonight. Just to see if it makes a difference. I am almost wondering if my cheap air intake is causing the issue. Going to throw my stock intake back on first to see if there is a difference.
Tonyrodz
Resident Resident
I've never had a problem with Taylor wires before. I have them on my 03 with long tubes with no issues. Sub'd.
its worth a try just to see before biting the bullet on coil packs or something else, I bought my last coil packs from autozone mainly because they had a lifetime warranty.
I swapped could packs,one,by one for a known good one that I have. Put the old plug wires back on. Sprayed carb cleaner around the manifold to look,for,leaks and still haven't found the problem. Thinking about pulling the plugs one by one to check them.
Tonyrodz
Resident Resident
A mechanic put a scanner on my Express van. It has the LS 4.8. I've been getting p0300 for the 4 months I've owned it. Cylinders 1, 5, 6, and 8 shows misfire. Guess I'll do plugs first. He said it could also be dirty injectors but it only has 119,000 on it. I've done wires already.
I only have 100k on this and bought it thanksgiving week. The problem is I didn't really drive it enough to really notice if there was a miss before I did headers,plugs, wires, cai and tune. Guess I am going to have to find somewhere local with a decent scanner and a decent rate to check it out.
Tonyrodz
Resident Resident
Please let us know whatever you find.
maybe a short somewhere? checked all the grounds? any other codes?
