My truck idles at around 550 RPM. Occationally, it will feel like it stumbles and the Fuel pressure will pop from 36 to 40PSI. Anyone have any idea what is going on?

Coldie

 

but I did have this same problem corrected today. Coil # 5 (passenger front), plus plug replaced. Will try to talk to tech when I go to SVTOA meeting tomorrow about exact cause. suspect coolant leak,but thought that usually happens on #8 rear, passenger side? If not that loose plug, or clogged fuel filter would be good bets. Good Luck!

 

Any way to check the coil packs? Can the dealer handle it under warranty?

Coldie

 

mine was done under warranty 3/36 expires next week, but only 11.7k in mileage. Thank God I have extended, too! When I went back to check, he had some kind of black box about size of laptop on top of my console,plugged into OBD port. don't forget loose plug or clogged fuel filter a possibility, too! How many miles on your truck/fuel filter? Good Luck!

 

Truck has 14K miles, plugs have been changed twice and fuel filter was changed at 10K.

I'll check the IAC and TPS tonight...

Coldie

 

I know this sounds strange, but I noticed my truck started idleing a little rough after I unplugged the boost bypass solenoid connector. I ran it this way for several months then plugged it back in and the idle smoothed back out.

 

but I'd sure remove all mods before taking it in! With 2 plug changes, I am assuming mods? Certainly presence of non OEM plugs will also suggest mods! I've never disconnect boost bypass

 

Yup, plenty of mods.

My dealer is very cool. If a mod caused the problem I pay them, if not, the warranty pays them. They've never made a comment except that if I ever have installed a chip I should make sure I don't have one on when I bring it in...

Coldie

 

you'll be fine at your dealer. Wouldn't to mention the possibilities,but just let them diagnose it, having your favorite SVT tech do it!

 

With a low and/or erratic idle; my first 'fix' would be to clean the IAC...............

Other possibilities:

1. Vacuum leak(s) at the intake manifold or at one of the vacuum hoses.
2. Leaking EGR valve or plugged PCV valve.
3. Air filter clogged.
4. Fuel pump not delivering sufficient fuel
5. Leaking head gasket.
6. Timing chains worn.
7. Valves burned.
8. Camshaft lobes worn.
9. Ignition system not functioning properly.
10. Fuel injection or eng. control systems malfunctioning.

 

Passenger front is #1 not #5, #5 is under your throttle body

 

in mis identifying position of #5 coil! Any thoughts on why it'd go bad? Doesn't seem like coolant leak possible if under throttle body? Thanks for any insight!