Serious Mid range lag...help

B

Bootlegfab

New member
Joined
Mar 24, 2014
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9
Evening all, I'm on day five of trying to figure this issues out. :nail: At 0-1/2 throttle and up to 1800 rpms the truck is snappy and responsive just as it should be. As the rpms pass 1800 it seems to lag big time...1/2 to WOT doesn't really make it do much, unless I STAB it and get it to downshift. Rail pressure hovers around 17k at this point...more pedal does not raise rail pressure at all. As the rpms pass 2400 my rail pressure hits 21-23k and the truck comes back alive. Max boost I'm seeing is 32psi on an He351 with waste gate blocked off. Truck specs are as follows : 2004 HO 305 motor, smarty sr., Airdog 100 with fresh filters, DAP intake plenum, He351 swap with blocked waste gate, homemade intake with clean Amsoil filter, Arson 3 kit on my cp3, 83k miles on original injectors, 5" straight pipe. Sorry it's kind of a shot in the dark to expect a diagnosis this way, but I'm stumped...I got come help on another site, but thought I'd give CompDiesel a shot. Here's a link to a video of the gauges on a pretty aggressive run, maybe someone can say if the numbers are average. I've tried smarty settings Sw5,7 and 9 with tq on 4 and all other settings default and it's the same issue on each.

[ame="http://www.youtube.com/watch?v=9Sl5_9L5Ek0"]http://www.youtube.com/watch?v=9Sl5_9L5Ek0[/ame]

Thanks for reading.
 
i cant view the video so maybe i shouldn't open my mouth, but from the sounds of it i would start with a easy FCA swap or data log the FCA.

considering your rail isnt happy i would lean twords your cp3. have you tuned it back to stock? and bad smoke or rough idle at all?

am i on the right track guys?

-M
 
I just put the new FCA that came with the arson kit on Friday. I'll unplug it and check. I don't believe my CTS will read the AIRDOG pressure but I'll check. Perhaps the SOLUS can read it. If I had injectors going out could that cause low rail pressure? I'm still seeing 23k once the rpms get up. Does 32psi seem right at WOT? I would think with the boost elbow closed I would be seeing higher than that...not that I want much higher...but I think it should be. Maybe it's as simple as a boost leak. On my he351 swap I just put a valve in the vacuum line to the waste gate and closed it. Maybe I need to remove soldnoid entirely and plug it. Appreciate the help.
 
Youngdiesel27. I got your PM but I can't reply yet. I will check the inter cooler tomorrow. Thanks. I'm leaning towards a boost leak as this all seemed to happen after the turbo swap. Honestly before the issue I rarely looked at my RP other than making sure it wasn't rediculously low or high.
 
FCA unplugged spiked RP to 23-24k. APPS checks out, didn't test MAP sensor but I did clean it. Local parts houses don't carry them, so I'll order one to be safe. New batteries installed. Made up a boost leak tester and applied 22lbs to the intake tract. I could hear leaking around the intake plenum. I went back through and checked torque on the plenum. Found three bolts which were under 18lbs. Also the gasket at the intake horn was blown, despite it being new. I swear I did the plenum install sober. Torqued the plenum and intake horn with new gasket to spec. Due to family reasons I only was able to do a quick drive around the neighborhood with sw5 loaded. At half throttle I saw 18k and 33-34psi which is more than I saw a few days ago with sw7 and sw9 loaded at WOT. I'll load a hotter tune on Thursday and cross my fingers it was a couple of boost leaks causing my problem. Given the fact I only started having this problem after the turbo swap/plenum install...I'm fairly confident I've got it solved. If it is that simple I'll feel stupid, but I can't thank you guys enough for talking me through it. I want to thank YoungDiesel especially. Even though I'm new here he PM'ed me when I first posted this and provided his personal cell number and offered to help me out via text/phone. Over the past few days he has enthusiastically walked me through diagnosing this problem. I'm glad I stumbled over to CompD.
 
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Again, welcome to the forum, glad to hear you got your problems figured out. We have some of THE BEST folks out there
 
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