I am having starting issues with my 98 Silverado 5.7L. It starts fine in the morning but when I get out of work and get in my truck to start it, it won't start. I wait 15 minutes and she starts right up. What on earth is going on? It does not happen all the time. Mainly when it's been humid during the day. I have changed the coil pack, wires, plugs, fuel relay and map sensor. I suspect it's a security issue but how would I go about finding out? I think this because of the 15 minute wait time before it will start.

Thanks! Need advice desperately

 

air,spark,fuel,mechanical. discount air if works fine cold. discount fuel if it happens by temp. spark...

on humid days indicates electrical / wire arcing. dirty wires can arc, once they arc theres a hole in insulation you (can't) repair. try cleaning engine and or replace wires. (NOTE: read about how to clean engine properly with spray-nine, engine cold, avoid sensors). due to todays 20k V wires they are famous for being a problem when humid

on humid days the airflow sensor MAF readings change because the hot wire reads diff air density/resistance. those are expensive. you have a clean air filter right? i'm unsure if to say "clean it" because they're expensive and if cleaned wrong you'll damage it. insure stuff isn't trapped between wires though.

 

I recently found a similar issue that had a strange roundabout diagnosis evasion going on. I'll explain that in more detail in the thread I started on that subject in Gen tech. but long and short of it, take a look at the crank position sensor. Watch your tac to see if it's reading your RPM correctly. I say this because I have a car with a CPS shot out on it that didn't produce a CEL code until after other unrelated existing codes were cleared out of the system.

 

Changed distributor cap and rotor but the thing is it would start in 15 minutes after initial try. Hasn't happened even in these dog days of Indiana weather since Saturday but who knows could anytime. Any more idea's if it does?

 

Never mind truck didn't start yesterday....wait 15 mins start! Could this be the security system?? It cranks but will not start after waiting 15 minutes it starts right up??
What would be the next step? We have changed the the dist cap and rotor, module, and coil, map sensor, fuel pump relay and the wires were lifetime and new 2 years ago as well as the plugs. New fuel pump too. At our wits end here but seriously think it's the security. Have tried another key that has little use too. !!

 

I have experienced the Security lock out thing, It will not start, no matter how long you wait.