p0302 & p0137

[uk tahoe]

Hi , all just an update i ordered some ac delco plugs and leads fitted them today and truck seems to start better and runs better , but p0302 now comes up all the time with this plug and lead setup when i took the tahoe for a drive the check light was comming on then going off unlike before when driving around town it stayed on all the time .

now when i go up a hill and and give it some the check light gos off weird soon as i come to a stop at the lights or traffic it comes back on , today i also unpluged my maf sensor and its idles abit smoother and the check light for maf unpluged come up but no misfire code , left it running for 5 mins to see if the missfire code poped up but it didnt with the maf plugged in check light comes on right away with misfire .

could really do with some help on this really doing my head in . thanks

 

[2003denali26]

Any update? did you end up solving the problem, having exact same problem with my 2007 tahoe, i have changed plugs,coils,swapped injector from 2 to 4, swapped wires from 2 to 4 , cleaned all injectors, took off valve cover to check lifters / rockers all good, thanks

 

[retiredsparky]

Since the problem stays with the same cylinder, you could have an injector issue, or a stuck valve that is not closing properly, injectors are a more common problem. If you pull the injector, you can verify it's operation in a simple manner by doing a youtube search for injector cleaning, using a 12 battery to open the injector and a can of carburetor cleaner to pressurize the injector. The visual evidence may help to decide if the injector is functioning correctly. Good luck.

One other possibility that is not likely is the purge valve for the evap system. If the valve stays open, the engine runs lean.

Have you changed the intake manifold gaskets? That is another possible cause.