I have a 2002 LS and it takes a few tries to get it to crank. However once started it has some hesitation at random times going down the road. High RPM's and low. So far I have replaced the valve cover gaskets, fuel pump, fuel filter, and spark plugs. Niether of these repairs fixed my problem. There are no light indicators showing that there is a problem. My next step is to clean out the injectors and or replace the coil packs. I have put alot of money into it already and am hoping to receive some guidance through this forum. If the coil packs miss will the check engine light illuminate? Does any body out there have any suggestions about what I should do next?

Thanks,
MarcusB704_02LS

Welcome to the forum!

Your first sentence would indicate that sometimes the engine does not even turn over, no starter engagment (ie: 'crank'). If that's the case, coil on plug (CoP) packs and injectors will NOT be the problem. That would either be an electrical issue or a starter issue. Make sure the 'Theft' or 'Security' light is not flashing when the car won't start.

If the starter engages and spins the engine over, but the car doesn't start right away, then it could be a restricted fuel filter, weak fuel pump, severe vacuum leak, misfires, injectors, or even just an old battery.

How old is your battery? You might try searching this forum for "battery" to see if the symptoms match yours.

Beyond that, you're going to need to determine if the issue is starter, no or low fuel, or no spark.

-Rod

Thanks for replying,

The battey is fairly new and it does start after 3 or 4 turns of the key. But it does not act this way all the time. Sometimes she starts right up with out a problem also at times it seems to start early. But as previously mentioned I have changed the fuel pump, fuel filter I had the altenaor rebuilt as well. Also changed the valve cover gaskets and got all the oil out from around the spark plugs. I treated the gas with STP fuel injector cleaner as well. Sorry to run down the list but this problem has me and my mechanic stumped. Rode around with the diagnostic computer hooked up however it returned no results. Everything seemed fine on the computer while the car was hesitating down the road.
I combined both problems because I think they both stem from the same aggervating problem.(The hesitation while under load at low RPM and not starting consistantly)
Any further advice would greatly be appreciated.

Thanks,
MarcusB704_02LS

I'm still unclear as to if the starter spins the engine over those times that the engine won't start.

As for the misfire, a professional scan tool with a misfire monitor feature or component parameter setting should be able to quickly tell you if you have a misfire issue or not. You might check with your mechanic to see if their scan tool (such as an OTC Genisys or similar) can monitor misfire counts real time, as well as short term and long term fuel trim values. Knowing these values should help determine if the roughness is due to lack of spark/too much fuel or too much air.

-Rod