I got my FASS 150 installed today. Drove over 400 miles total. I can relate to the observations in this thread. The results of my limited testing:

CL and TST 0/0---- no problem

BDDL on Performance and TST on 3/4 stumble at higher RPM.. Laying on it at 2,200 RPM or even less will do this and then clean up. This happens just when you roll into the throttle. This is in OD.

BDDL on TOW and TST on 3/4--- about the same perhaps???

BDDL on Stock and TST on 4/5, a slight bog and no stumble. HUGE EGT's. The highest I have ever seen The BDDL is doing something here to run cooler. Very interesting!!

BDDL on Performance and TST on either 0/4 or 1/4 or 5 Te/power is good.

I did adjust timing limits down to no positive effect. I'll have more on this later.

It seems the Te on the early and agressive twins program(s) is draining the rail. This is a CP3 pump issue I believe.

I do have a rail pressure gauge. This is helpful but the rail pressure changes VERY quickly and is difficult to monitor on a run. Mine actually seems ok, but I will do some more research and report back. The rail pressure is related to RPM. It is difficult to explain, but the changes and events happen so quickly that the stumble might just appear as the rail not rising quickly enough. You really cant watch this in real time with your eyes. You really need to see commanded values and actuall values and record them.

I think the ultimate solution is to have a DRB or 'equivalent'; something that actually has recording capabilities. I have this solution but have not purchased quite yet.. PM me for the info.

Sorry for the long post. I actually will have more to say about this.

Chris

 

I think you've got your setting just backwards from my testing and that of Gypsyman. The te is causing most of that rail draining excess. Try a 3/1 or a max of 3/2 for the te and I think it will get much better for you. For Richard (Gypsyman) he was able to run that stack, unlike myself, with the BDDL on tow and he had his TST on 3/1 or 4/1,... pretty sure. Also he runs the VA C3.1 small fueling box. He's into the 600's with that stack along with F1 injectors. All trucks are NOT created equal and some of them will run with a setup that others won't,.. crazy deal. But from what I've seen the te does help or eliminate the pop when it's turned way down if not off and it doesn't hurt the performance either.

 

OT-OF-Here is right on. The sweet spot for my truck is 5x2, BDPP on Tow and VA C3.1 on 100%. I tried 7x3 with the rest of the settings the same and dropped just over 130 HP on the next pull. Let the truck cool a bit, dropped back to 5x2 and she broke 600 hp again. Any higher than 2 on the TE and I lose power on the top end. The rail is pulled too low early in the run and never recovers.

I know what you guys are saying about the popping. If I step the BDPP up to performance my truck makes some gut wrenching sounds on the top end. Sounds like the metallic sound of pistons kissing valves even though I know it's not. That's just the best way I can describe it. The SO trucks seem to get away with the Performance setting on the PP more often than the HO trucks do. Less initial timing in the SO programming maybe? I still don't know for sure.

I stepped my lift pump pressure up from 17 to 25 and the truck pulls better on the top. I picked up 4 lbs of boost on the top end and hit the relief valves at 64 psi every run now. Still get the crazy sounds on the Performace program though.

Time for another trip up to PDR to see if I can squeeze one more power level out of the TST before it lays down this time.

Richard

 

Thanks, I appreciate the assistance. The Te is definitely a killer. I am wondering if a softer TST program would help me?? like the regular twins.

I can say one thing for certain, my EGT is way up after the FASS install. I actually hit 1575 last evening; trouble is, the defueling is set at 1400 It never overshot this much before. I have to believe it is getting fuel. I need more air. The wastegate opens at 40. I need to change this.

I am also showing a mileage increase. Just doesn't make sense. I am over 20 mpg. This was driving 75mph, RPM was 2,100, EGT was 600-640, boost was about 5. Hand calculated. Hmmmm

I got off topic a little, but hopefully this will keep it up there a little longer. I forwarded some of the TST popping and stumble threads to the folks at TST. I will ask them next week.

Chris

 

I used a quote from Mark Chappel in my earlier post so I hope you show that to Mark and see if he adds to it. It would be great if someone with this problem could visit Marks shop and he could see/dyno and drive that vehicle and maybe he could come up with the fix. Personally I think with this adjustable timing feature that is in the hands of the user now with their latest upgrade then perhaps we have it in our power to fix this problem by turning the timing down probably 3* to 6*, would be my guess. Nothing worse than having power you can't use.

 

I forwarded all the threads includiung the one you reference. I think four total. BTW, I have the adjustable timing feature on my program. I tried changing the auto limit from 12 to 9. Same thing. I didn't go any further and have much more to do with this. I know it would be the ticket for those using NOS.

I need more air..........

Chris

 

After speking with Mark@TST for some time about this thread, I can say that the conclusion is that we are running the CP3 rail dry. The CP3 is a positive displacement pump and fuel delivery will relate to RPM and several capacity limitations inside the pump. It seems the limit is about 180 or so addtl. hp from what they have seen in their testing.

Basically, you have so much initial volume and if this is hit hard early on, the rail will sometimes never fully recover and it is all downhill from there. You only have so much volume to use in this positive displacement pump.

As many experienced menbers here have said as well; some of the better HP and even torque numbers are found using less fuel.

Of course modification was discussed, and he agreed that this was the next level of performance. He has his own ideas. I will not go further.

He completely agreed that the Te setting should be kept at an absolute minimum or elminated for those stacking, especially with the twins programs.

They have many interesting things planned for the near future. Their desire is to provide one performance product(s) that will accomplish everything. Mark is aware of many, many more things than may appear obvious.

I can say this; Whatever suggestions you may have, send to the TST tech. support email. I now know Mark DOES actually read these and forum threads as well.

Chris

 

There are several members here with modded Cp3's that experience the popping with rail pressure never dropping remotely close to being "dry". I had it with 26,000psi, with 25,000psi, all the way down to 19,000psi....I'd say that is not it. Hopefully Mark doesn't stop at that conclusion. I ditched the twins program and no more popping.

 

yep, not sure if I buy into the rail is dry. As I mentioned numerous times before, mine is popping when my rail pressure gauge is showing 23 and 24,000 psi of pressure, just like AKRAM.

 

yeah, my rail ain't dry either. It is something else. Hopefully Mark will sign up and help us troubleshoot this problem! I may try sending my TST back for the "adjustable timing" option and see if I can get better results.

 

Mine doesn't so have the popcorn effect, rather if you step on the pedal, it kinda hesitates, POP(good puff of smoke with it), and its off to the races. If the rail was dry, then why the good puff of smoke?

I've had it on 5/5 almost everyday. Yesterday, I set it at 7/2. The bottom end seems the same, but the top end smokes more now and pulls harder than it did at say 6/5.The pyro can bury itself to 1400-1500 is a heartbeat.Gonna try 7/1 and see if that doesn't help with the pop

Keep in mind, mine is not stacked. It actually didn't do it as bad when I borrowed a EZ box for a couple of days.

Thinking that the CP3 is chilling/crusing along.....then TST opens the injectors big time, and the CP3 goes "OH CRAP....I need to wake up". While with a pressure box, the CP3 is keeping that pressure higher, so when the TST opens up the pulse width, the pressure doesn't drop as low as it would otherwise, so the CP3 doesn' have as much to catch-up.

The TST runs great, just wish it had more bottom (need a pressure box to fix that I guess), and that hesitation/pop thing-a-bob would go away.

 

Well, that is a perfect description of what I can experience. I really think we are dealing with two distinct issues. Give a call to Scott@TST and he can give an explanation of what the 'stumble' group is experiencing and why. I won't even try to relate the technical stuff now. I am too tired. They can re-produce the same thing at will on their own trucks. I truly believe stacking the BDDL with the TST, and perhaps other products makes a nice improvement here. It does for me. I mentioned this to Mark as well. I even have noticed my peak EGT is lower stacked with the BDDL. This does not make sense to him as there are only about three parameners to adjust to add power.

I think some are dealing with a pump limitation. In my own testing, I have not found rail pressure to be a good indicator. Try changing to a 'softer' TST program and I bet your problem goes away. Some of the brutal mid-range will too which we all like for the street. They are in fact experimenting around with fuel pressure.

The other issue is the 'popping'. I have never personally experienced this, but I am darn sure it is real. This must be another limitation of some kind. This is the real question here on this thread.

Chris

 

The popping is most probably what Mark said early on about backup pressures fromt he Intercooler into the Turbo. As I've said a few times in this thread,... I ran this exact same combo of stacks and such and never had the pop b-4 I went twins and I know a couple have pointed out that your fuel demands go up with the twins but I will be addressing these possibilities one at a time with the adj timing feature being the 1st thing I try and then I am going for a CP3 mod.

 

There are at least 5 people I know with modded cp3's that are getting the "popcorn" popping sound on WOT runs, and none of us are having the rail pressure drop too low. In fact, I can re-produce the popping with the TST on 1x1 (timing only) so that leads me to believe that it is a timing issue. With the BDDL on 90 and TST on 0x0 it runs great. Change the timing only by adjusting the TST to 1x1 and the popping is there.

 

I'm more interested in hearing more about this "stumble" as I still have it occasionally.