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LS swap troubleshooting. no start. and solved the issue

chaplinfj60

Well-known member
Joined
Nov 17, 2020
Member Number
3057
Messages
3,435
Loc
marshalltown iowa
good afternoon all

i just want to put out some of the things we learned this weekend about troubleshooting a no start issue on the 5.3 LS form a 2005 yukon, that was the donor engine for my swap.

so this weeked we tried to do a test fire and make sure all the wiring was hooked up correctly for my LS swap.

we tested the fuel lines for leaks before we attempted to fire the engine and two fitting need a bit more tightening. no biggie but glad we did that first.

i am using the fitech stand alone kit and everything went super smooth on that end. no drama there. so we power up the hand held computer and set all the setting it said. so far so good. sent all setting to the computer, cycled the key and try to start. nothing, sputter sputter bang bang. but no start.

ok check setting again. found the setting for the cam was wrong, i am using a stock one. re sent that to the computer. save . cycle key try again

nothing check codes. IAC and TPS what the hell. ok after a while we decide it is these two sensors. go to part store and get sensors. put in no difference.

now we are going full trouble shoot mode. do we fuel. yes 53 or so on a gauge. no issue there. do we have spark. no # 2 is not sparking. and sometimes #6 not sparking. now we are thinking its bad plugs, after all i built my own. so now pull all plug wire test each one. they all work fine off another coil.. damit. what the hell.


about this time the starter quit. ok go back to town, part store starter 220 bucks, i said no way.. got another used one form buddy dave and we back to the shop. while starter is out decide to put original crank sensor back in.

put everything back to gether and tried it again. this time it almost started. but still back fired and nothing. its acting like 180 out on timing.

checked coil 2 again no spark at all. go back to town, buddy of a buddy had set of coils, swap them out still dead #2 coil. what the helllllll.........:shocked::shocked::shocked:


ok at this point we decide to change out the cam sensor i put in there. the new one, went back to the old and tried again. and holly crap fired right up.....

so what i learned was just because a sensor is new does not mean it is good.

so it turns out if cyl 2 has no spark its could be a cam sensor throwing things off. learning experience for sure.

i will post a vid of it running
 
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