I have a 04 silverado HD 2500 4x4 with a wynjammer s/c, 43lb injectors, and a westers tune. I was getting pinging as the rpm went up so I checked the fuel pressure at the port on the fuel rail. The fuel pressure started at 58lbs at idle, then went down to 48-50lbs at 5500 rpm. I then replaced the stock pump with a walbro 340 pump. This made the pressure at idle 60lb, but it still goes down to 52-53lbs at 5500 rpm. I am getting pinging starting at about 3000rpm. What might be causing this? Thanks for any info.

 

That fuel pressure is farily common on Returnless fuel systems like yours ( mine as well) that are boosted. Now the 48-50lb was Low, but 52-54lb seems fairly common. As too the pinging it could be too much timing or not enough fuel, do you have a wideband? Is that supercharger intercooled? How much boost are you running? Need some more information man....

 

Wideband? Intercooler, no. 6 lb of boost at 5600rpm. The pinging really starts when you give it some throttle, anytime over about 2000rpm. I was told to try replacing my mass air flow senser, but that didn't work either. Thanks for the help guys

 

Could be the tune(timing, fueling), injectors maxed out due to low fuel pressure, low fuel level in the tank(pump aeration), etc. A wideband Air/Fuel gauge would tell you if it is going lean in boost. Do you know anyone with HPTuners or EFILive that could log the relevant parameters to see what is going on?

 

With no intercooler and only 6lb at 5600 his injectors shouldnt be maxed, although close. I would like to see the tune as well, I wonder what it is set to go into PE at?

Man I wish I could help ya but there are some parameters that are needed to know what is going on. As Drx and myself mentioned above, you really need to gain access to tuning software to see what is going on as well as a wideband Air fuel ratio gauge.

 

Lyndon is a good tuner but no way i'd have a mail order tune for FI application. You don't mention your local but I'd be looking for a dyno tuner near by.

 

Drop in the fuel pressure means you more than likely need a little more PE. Anyway you have a wideband to log the a/f ratio?

 

Trever1t, I'm near Rochester, ny. Anyone know someone around here that can tune? YenkoST, what is PE? Thanks again

 

Power Enrichment = PE

I would also look to see if there is a PE delay set, not only what level it is set at. I would HIGHLY suggest getting some scanning software to see what is going on there. By having this software, you can log runs and E-mail them to your tuner for tweeks. As mentioned, in person tuning is HIGHLY suggested.

BTW, your FP is "normal" for an 04. My question is: where is your IAT sensor mounted in relation to the supercharger. Is it still in the MAF or has it been relocated to the boost side (discharge) of the compressor. Something tells me that the Wynjammer "kit" doesn't have a relocation requirement due to its lower boost levels. You may be having high IAT's however your PCM "sees" ambient.

 

Bignred....just like Krambo said. Basically, it add more fuel as rpms increase or but only at a certain percent throttle....usually 50% or above throttle %.