93 Deville, Injector Diagnosis (long)

[up2ng]

On a 4.9 (93 deville) what is the easiest/best way to find a leaky injector ?

I have come to this conclusion while on a search for better gas mileage. I have checked the FPR and there isn't a leak, there aren't any vacuum leaks, I have changed air filter, plugs, wires, cap, rotor, cleaned the EGR (TB side and intake holes), changed the O2 sensor (no signal) and PCV. Engine temp is always between 91 - 100 and the 02 sensor reads between .05 - .80 at idle (600-620 rpm). If I start the car when the engine is warm the idle will pulse about every 2 seconds for around 30 seconds. No problems cold starting, it has never stalled and always starts on the first try. At times there is a rotten egg odor and sometimes its quite noxious !. There are no stored or current codes (not since the O2 sensor last year)

If I open the throttle plates when engine is off I hear a faint bubbling noise and the TB smells faintly of gas. Whe I rev the engine to around 3000 rpm and let go of the pedal it is sometimes followed by a small pop in the exhaust.

So to make a long story short, I think I have an injector problem. I hope I gave enough info to go on !

Thanks

[KevinW]

I don't know if a cylinder balance test is possible via the OBD on a 4.9 C-car. Try measuring the injector coil resistances on a hot engine. The easy way is to unplug the wiring harness connector for each bank and probe the pins. Note that the RH connector has a couple non-injector pins.

[Ranger]

Pull the fuel rail with the injectors still attatched and turn the key on to energize the fuel pump and pressurize the fuel system. A leaky injector should be very evident at that point.

[harddriver]

Have you had the cat converter checked my mileage went from 9 city 14 hwy back to 18 city and 23 hwy when I had mine changed. 93 Deville 4.9