Surging problem at constant speed

[Tom Keiser]

I'm new to Supercharging and need help with a surging problem.
I finished installing a V1 SC-Trim this weekend, it runs great while
accelerating but won't hold a constant speed on the road with out
surging. If I hold My foot steady, It's kind of like 5 seconds of normal
followed by 4 seconds of no power and then back to normal, never
ending cycle. It seems to be loading up, when I make a slow turn
around, it coughs, pops and bucks until I blip the throttle hard to clear
it.
I thought it might be the FMU so I bypassed it to see how it would
drive at part throttle, no change at all. So, I think fuel delivery is good,
air delivery is real good (6 lbs.) and now I'm wondering about the
possibility that it could be spark related. I would really appreciate any
input. Here are the motor details.
302, stock compression
Adjustable FP regulator, set to 38lbs. at idle, hose off.
Stock TFI distributor.
10 degrees base timing, spout out.
new plugs gapped at .030
MSD 6A
65mm TB
75mm MAF
24 lb. injectors
E303 cam

Thanks; Tom

[regattacoupe]

sounds like you need a bypass valve Tom. It is forcing air past the throttle blade. Do a search for bypass valve and you should be good to go.

[Tom Keiser]

Thanks for the quick response Brent,

I'll get a valve and give it a try. My kit instructions gave no indication that this would be needed but My recent (the past week) research, suggests that it's a good idea for any SC setup.

Tom

[Tom Keiser]

I should have posted this a couple weeks ago when I got it running right. A bit embarrasing but maybe it will help someone in the future. It turns out that while finalizing the "simple" things, I was not paying enough attention and put the MAF on backwards . The sample tube has a hell of a time trying to get a good reading from the small end. It ran great at full throttle and Pig rich at anything less. I used 3/4 tank of gas in about 45 miles. I learned that I needed an 8:1 FMU recalibration and that a bypass valve would be a good idea, both are done and it rocks now.
It will probably never see a Dyno, whatever it's making is plenty in a 2,240 lb. car.

Tom

[fanglemeister]

Sweet! Kudos on the ride. I was wondering if you are using the EGR valve on that Explorer intake or just have it hung on there for the position sensor to work -- iirc the Explorer EGR system uses a much more sensitive position sensor compared to the older Mustangs, reduced exhaust backpressure screws it up. if you are running egr through the valve, you might ought to reconsider connecting the egr coolant lines. What are you doing for crankcase ventilation?

[Tom Keiser]

Chris, Thanks. All of the smog gear has been removed. Resistors were added to the TAD & TAB circuits to keep the codes out. The EGR was left in place for the sensor operation only so I just plugged the lines on the TB. As far as crankcase ventilation, after the picture was taken, I ran the Vortech supplied rubber tube with steel filter from the oil filler tube to a brass fitting on top of the intake elbow (shiney spot in the picture). Since I only have the basic plastic tube right now (Supercharger was an Anniversary gift and I didn't want to get greedy), I tapped into the bottom of it for the bypass valve. I still need to get a Turbo Coupe PCV valve but it's all working great now.
Tom