Ok. After drinking a few cold ones, my roommate and I came up with some ideas. How about stacking a TST PM3 Comp with an Edge comp but leave the wire untapped on the edge so it acts like an EZ. With that combo, not only could you adjust the main power levels on both boxes but you could also control the fueling levels on the comp. Or, how bout stacking the TST with the comp and tapping the wire. Would that work or would that be to much fuel? If there's to much fuel how bout putting some sort of swith on there that would have the comp running in EZ mode until you reach a certain boost level or you manually turn it on and it turns it into a normal comp. That way you'd already have the RPM's built up and have the air to burn the fuel. So what do yall think?

 

The first option (Comp w/ untapped wire) sounds doable. This would give you the equivalent of a TST/EZ stack, with the ability to control the setting of the EZ from the cab. On Ray's truck yesterday, adding my EZ to his TST improved his peak HP number by 55hp ('01 Dodge auto).

As for the second option, I don't think it's possible to run two wiretap boxes. I have a feeling that they would conflict on the signals being sent to the VP44, since the primary function of the wiretap is to keep the VP44 fueling after the ECM backs off. I'd worry about backfeeding of the signals and possibly wiping out one of the boxes.

JM

 

What he said!!


KP

 

Ahh. Didn't even think about the conflicting signals part.

 

Hey Justin, you mind if we borrow your truck for a weekend and find out the hard way!!!

 

Well, since I'm playing catch-up by the looks of the results board right now...I'll need all the help I can get. We might as well try a 3-way stack while we're at it.

I was impressed though yesterday that my EZ added to Ray's truck gave him 55hp, since the box is rated for 65hp. On a mostly stock auto, I didn't think we'd see that kind of improvement. At least I know the box is working up to spec.

 

I wish I knew why mine dynoed so low. With the injectors and comp (in EZ mode) I should be over 260.

 

I just watched the video from your run and it didn't look like there was a bit of smoke. Between the EZ and the injectors, you should have at least got a few puffs.

 

I've stacked a drag comp (untapped) with a tst pm3 comp. Better adjustability than the TST/EZ stack at a much higher price. The throttle basically became an on/off switch.

brandon.

 

Aggiejustin, I know there was no smoke. If I stand on it from a stop I get a decent cloud though so who knows. I do know that if there's any boost and I get on it then there's no smoke.

Joefarmer, are you saying that the throttle was to touchy and was very hard to control or what?

 

Yep. Very touchy and the truck would buck at part throttle. The funny part is the Drag Comp alone has more power yet its throttle response is linear and predictable.

brnaodn.

 

Actually, stacking two wire-tappers would work sometimes. Other times it would not.

What would happen is that the pump solenoid is only going to "see" the more demanding usage.

Say you stack a regular Comp and a regular TST, both tapping the wire. The boxes fuel differently, so there will be times when the Comp is fueling and the TST is not, and when the TST is fueling more than the Comp. They WHEN to fuel and HOW to fuel is different for each box, as they look at different things to determine fueling, and they have different fueling maps.

The Comp looks at pedal position, boost, RPM, etc.

The TST looks only at boost, and the RATE OF CHANGE in boost. The TST operates off boost exclusively-- thus no CAN BUS connection for the TST. Thus the TST is simpler, and also able to get CARB certification because it waits for boost before it adds fuel. It's also why it has less bottom end than the Comp.

So the pump will respond to any fueling signal, whether it comes from the comp or the TST.

In the cases where the Comp AND the TST are fueling, the pump will follow whichever is more aggressive.

Voltages is parallel are not additive, but CURRENT is. So because both boxes are sending signals, it may be too much current for the pump solenoid, and it will overheat and fail. The other thing is that the magnetic field of the solenoid is a function of current, so the solenoid will be opening and closing with more force due to the increased current-- again, increasing the likelihood of failure.

All in all, the dual taps are a bad idea. No upside, just downside, imo.