Octane question

[Holly_Hobby]

Hi....I have a 2005 Chysler Pacific with 8,500 miles on it (I don't drive much). It's starting hard, no matter the temp outside. I have to push the gas peddle half way down to get it to start after it sits. I haven't used premium gas like the recommendation, I use the cheapest grade. Could this be causing the problem? Thanks.

[jimmil]

1. Rather Doubtful...

Octane has more to do with the ability of gas to not auto-ignite when subjected to pressure. At startup there is really nothing there that octane really can effect. Things that do have an effect on startup, depending on the motor of course, could be something like the fuel pump. When the ignition is turned on the fuel pump pressurizes the system. You can check the fuel pressure by attaching a pressure tester on the fuel rail which has a nipple similar to what is on a tire to inflate it. Check to see if you have the proper pressure. If not then it can be the fuel pressure regulator or the actual fuel pump. More often than not it is the pump. If the car sometimes starts right up and other times not then it is highly suspected that the pump is slowly going out.

If the fuel pressure is good then you need to check various sensors that have an effect on the start procedure. The first thing that happens after you begin the cranking sequence is the crank sensor tells the computer where the crank is in relation to what phase of stroke it is in. Once the crank sensor detects the crank's position it tell the computer where it is and then the computer looks for the cam sensor impulses. Once the cam position is detected and read the computer can tell the fuel injectors when to fire as well as when to fire the spark. So you can start at the crank sensor and trouble shoot from there.

Something that can happen although not so very often is you can have a leaky injector that cause problems when starting. To test that you need to pull the injector fuse at the fuse panel. Then you try and start the car. If the engine fires ANY then you can be assured you have an injector that is leaking.