LT1/4 hard starting

[dave69]

I swapped a 96 Vette LT4 back in Nov in my 69 C10 and it has been running great every day doesn't skip a beat, except lately it has been a little hard to start. It will start and run most times but when it won't it will pop at the engine (sounds like a back fire),but not out the exhaust and may be enough to blow off a vacuum cap and than crank for bit then start and run great. The next start fires right the odd time it will pop and crank awhile than start. I checked for codes and it has 2 P0135 and P1133. Do I need to change one of the O2 sensor? Not sure what is wrong.
Does anyone have some advice on what I should be checking and or replacing?

Thanks Dave

[Heavy Evy]

those are misfire codes and it sounds like a fuel issue maybe the pump
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[hugger6933]

Dave I am sure that you remember that a lot of those lt engines have [had] problems with the dist cap not venting properly and having a large buildup [or backup as it were] of mositure and condenstion in the cap. It casues a lagre amount of troubles with the running of the lt series. I know it is some trouble to get that cap off but it may be worht a shot. Sorry I don't know what your codes are but maybe a site like lt1.com or ls1 .com might help. Jim

[dave69]

Originally Posted by Heavy Evy

those are misfire codes and it sounds like a fuel issue maybe the pump
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Are those codes to with the O2 sensor? I just put higher octane fuel from 87 to 92. To try that because the knock count is 1600 if I remember right and if I get on it hard it will pin than stop pinning. Thought that is worth a try.

[cdowns]

maybe read up on the board rules about double posting