I have a 2006 MCS with 39K on that is having a hard time starting. It always starts and it usually doesn't take more than a second or two of cranking but it starts with a whimper and the RPM needle dips and occasionally yoyos for a second before leveling out either on its own or after I press the gas pedal. The car has a 15% pulley, step colder NGK plugs, RMW Bosch 550 injector that were bought second hand, and a RMW tune. On advise from Jan I swapped out the fuel pressure regulator with a used regulator I got from Way Motor Works and the problem persisted. I replaced the fuel pump with a Daewerks high flow pump that I bought from Colin but its still struggling to start especially when the car is warm or has been recently driven. Battery was tested and its good. I'm probably going to try replacing the fuel filter next. Maybe the used 550 injectors I put in aren't doing their job? Bad or improperly gaped plugs? Does anyone have any other ideas of what might be causing the issue? Any help would be appreciated.

 

I'd ask Jan what's next. I doubt the plugs are gapped wrong, if you have the NGK plugs that I think you have. The three prongs are not adjustable, and they are beside the center electrode and factory set, not in front of the electrode like the old school ones that need to be gapped.

Seems like low miles, so I imagine it's been sitting for a lot of it's life, so fuel filter might make sense in that way, however I think it's supposed to last for 100k miles. The last step of getting the filter housing lid to "snap" back on is really hard! It's not complicated, but you'll wish you had more hands and stronger thumbs. If you're able to get suggestions from Jan, if it were me I'd ask him before doing the fuel filter.

 

Thanks for the reply. I'm thinking I'm going to hold off on the fuel filter for now and just live with the weak starts. I should probably ask Jan for more advise but I don't want to bug him again quite yet. I'm sure he gets sick of people expecting him to diagnose their car trouble because they bought a couple parts or a tune from him.

 

Have you tried running a bottle of Techron concentrate in the gas? I have an 06 MCS with Dinan S2 mods, JCW injectors and RMW cams and tune and occasionally get rough idle and every once in a while stalling after starting a cold engine but it seems to be fine on the second start. Cleaned some corrosion off the coil pack leads along with new spark wires, changed the fuel filter and ran Techron through the gas. For me it was the cleaning the coil pack corrosion along with new plug wires and running the Techron. Seems like I need to run the Techron at least once a year to keep the rough idle from coming back.