I was wondering if it is just my car but sometimes it feels like it is down on power and is lagging. I did't know if it is just this terrible GA weather we've been experiencing. Thoughts/opinions?

 

is when lets say your going around 30 mph and you nail it, it takes like 2 sec's for the computer to realize then i am at WOT and then it downshifts then takes off. But daily driving i don't feel any lag, plus we have a supercharger not a turbo, so no lag : )

 

feels strong all the way up to redline. remember, it takes around 2.8k-3k when it really starts to hit.

 

yea i experince major lag! it sucks. doesnt kick in till 3500rpm then hits full boost. But wait, mines a turbo, my bad!
heehhe..

 

I am not talking about feeling "boost lag", I am talking about it feeling like it isn't running as strong as it usually does. Could it be the heat, humidity, and poor air quality bringing the performance down?

 

i had that lag too until i did what loren told us to do with the vacuum line to the hobbs switch. for some reason it got rid of that lag.

 

What did Loren say about the vaccum line and hobs switch? Can you give me more specific information on what I need to do or check out? TIA.

 

Per loren's email "Don't connect the Hob's switch it runs on to vacuum as the diagram shows. Leave the vacuum line unplugged and either plug off the main line or remove the T. This will allow the pump to run when ever the ignition key is on. It will dramatically improve reliability." Try this as for specifics you need to check with others.

 

I will give your suggestions a shot and see what happens. Thanks again for all your help.

 

do you have a CAI? I'm about to do one...hoping it helps.

Jim

 

I have noticed over the last year I would get occassionally a drop in base fuel pressure after letting off boost. A quick tap of the throttle would bring it back up. I have noticed that from time to time I would get some fuel leaking from the hard line fitting that the feed hose for the auxillery fuel pump goes to. I have tightened the clamps and replaced the hose, but it would still come back.

I finally found out why. The auxillery fuel pump runs off a Hobbs switch that allows it to only run under boost. When you let off and go out of boost, the fuel pump immediately stops and blocks some of the fuel flow dropping the pressure. This stoppage creates back pressure in the line and caused the fitting to leak due to the pressure. If the back pressure was great enough, it could actually damage the in-tank pump.

I originally thought about pulling the in-line pump and replacing it with a higher flow in-tank pump. I was suggested to just run the auxillery pump all the time. I talked to Vortech and they said the T-Rex pump was designed for 100% duty cycle. So,I tried it. The fuel pressure stays very consistant and does not run rich under non-boost conditions.

I strongly recommend that all SC owners do the same. If you feel any jerkinees going into and out of boost, it may be related to the same problem. To run the pump all the time when the engine is running, just unplug the vacuum line going to it and cap it off. There are no ill effects since it only provides additional load for the fuel that is already there.

 

Sounds like the typical fuel pressure problem. I've had the hobb's switch disconnected for over a year and driveability has been excellent. Basically, the Hobb's switch only turns on the auxillery fuel pump when you are under boost. When you let off, the auxillery pump stops. If the valve in thepump doesn't stop completely open, it partially blocks the fuel supply and drops the pressure. As a result, the engine is running very lean until you get into boost and the pump kicks back on. When you first press into the throttle, the engine is running very. The knock sensor goes off and the ECU retards the timing way back. If feels like the power is dead for the first 1-2 seconds as a result or it feels like turbo lag. This can be easily seen by installing a fuel pressure gauge and sender. If the fuel pressure ever drops below 40 psi, then this is the problem. I saw my pressure drop from a nominal 43-45 psi to 30 psi. Simply unplugging the vacuum hose at the T fitting that goes to the Hobb's switch and capping the T off will fix the problem.

The Vortech T-Rex was actually designed for 100% duty cycle and never intended to be turned on and off randomly why the car is driven(Stillen's mistake). Eliminating the Hobb's switch function will allow the pump to run whenever the ignition switch is turned on or whenever the engine is running. Base fuel pressure will increase about 3 psi. I have seen no difference in city gas mileage and a 1 mpg drop in highway gas mileage with this change, but I still get at least 25 mpg on the highway. Throttle response is always immediate, even with the stock pulley. Keep in mind with the stock kit, boost only starts building at around 2500 rpms and there is a torque ramp-up around 3500 rpms. Even at that, there still should be no noticeable "lag" to it. You should just be able to feel when the torque ramps, but low end response should still be better than stock.