Twin turbos not spooling at dead stop

T

tnevins

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I have a ppumped 24 valve with a s366 to a s475 and also with a custom runner intake, lately I have been fighting an issue of not being able to spool the Chargers from staging at the track, it will sit there and smoke and smoke but will never get above 1800 rpms, and won't build any boost, but going down the road or leaving on no boost it will spool up and act fine, I have 400cc of fuel for my injection pump 5ks, full cuts, no fuel plate but do have a fuel arm and .093 lines and crossover tubes, and 150 sticks, also I have a sinister sump kit to a freshly rebuild fass 220gph I have check all boots, clamps, etc. and can't find any leaks and with it locked up in fourth it builds 80 psi and I can't hear any air leaking, also another thing I am wondering is going down the road not locked up it only builds about 50 psi until I lock the converter up then it goes to 80 I have heard of people running the same compound setup with not nearly as much fuel and they run 75 psi not locked up, I don't know if those two issue tie together or not but if any one could help would be greatly appreciated. Thanks
 
1900 stall and a precision billet triple disc, I had a 1700 stall before and never had this problem before but I also didn't have the twin set up then
 
Also I have gotten the truck to build boost from a stop twice about two months ago and was able to launch but not lately, it just won't go over 1800, so I know it will do it just don't know if maybe it's something simple that I'm over looking or not
 
Sounds like a converter issue to me to. If your able to push 80psi even in od locked but nothing at all while staging its hard to think you have a boost leak. I have had a cracked manifold and blown apart wastegate cause a bad spool issue but you dont have a wastegate

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Could be the factory 24 valve torque management. That will definitely limit your RPM/boost from a stand still. I understand you're P pumped now, but maybe theres still torque management running in the ECM/PCM.
 
Noah Serynek said:
Could be the factory 24 valve torque management. That will definitely limit your RPM/boost from a stand still. I understand you're P pumped now, but maybe theres still torque management running in the ECM/PCM.
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That's how mine did with torque management, only could make about 5-7psi stopped and held fuel back till 3rd gear but it never let me build boost on the line a single time so unless it's somethin weird with the pump swap my guess would be converter not lettin it stage up
I had this same problem a while back. Made good boost drivin but wouldn't boost at a stop. Turned out the air filter was stopped up just enough to not let it build from a stop, but I'm sure you've already covered that
 
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I don't think the p pump ecm is your issue. Is it a night and day difference when you lock the converter? 50 psi unlocked tells me you are turning that power into heat in the transmission. At the same time if the converter isn't working right or very loose you should have no problem bringing the rpms up to build boost. It almost sounds like you ended up with a tighter converter since you get 1800rpm brake stall out of a 1900rpm converter. If it's not the converter it has to be in the tuning.
 
Noah Serynek said:
Could be the factory 24 valve torque management. That will definitely limit your RPM/boost from a stand still. I understand you're P pumped now, but maybe theres still torque management running in the ECM/PCM.
Click to expand...

How would the ecm affect fuel delivery and timing from a p pump exactly?
 
You're correct, it does sound like a condition similar to tq management, but how do you believe the ecm enacts tq management?

To the op, how recent has this been happening? Last week or two, or last month or two? As in possibly since the weather has probably become very hot and humid July, August, Sept. weather?

Could be as simple as that, a leak in the charge air or exhaust piping, melted/damaged turbine wheel, cam lobes wiping off, etc. If it's reaching the same rpm at the line as before, I doubt it's a converter issue.
 
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