5.3 in a Jet Boat
5.3 in a Jet Boat I have O2's on the motor now and it still runs bad. It will rev to about 4,000 rpm for the first minute or so, then as it warms it falls flat. During that first minute I can get about 2/3 throttle response. Any more than that power drops off. After the first minute or so when power decreases it falls rapidly to where it will barely run about idle. I do run lake water for cooling so the engine temp usually never gets above 104 degrees.
I'm running a 5.3 with stock injectors, ported heads that are milled for 10:1 compression with a 226/229 .575/.578 on 112 cam and on a DBW throttle that seems to be working correctly. With the motor not running the throttle blade has full movement.
It's gonna go back on the water Wednesday night for the next lake test. I'm open to suggestions to get it to run. Maybe go across the board and jack up the ECT tables? I've tried messing with the torque management setting but they had no effect. There has to be something simple that being missed here which is not letting this motor cut loose. This thing should be able to turn 5,100 or so rpm with the impeller that in the pump if I can get the last 1/3 throttle to work and for longer than a minute.
Here's all the files that go with the motor.
I'm running a 5.3 with stock injectors, ported heads that are milled for 10:1 compression with a 226/229 .575/.578 on 112 cam and on a DBW throttle that seems to be working correctly. With the motor not running the throttle blade has full movement.
It's gonna go back on the water Wednesday night for the next lake test. I'm open to suggestions to get it to run. Maybe go across the board and jack up the ECT tables? I've tried messing with the torque management setting but they had no effect. There has to be something simple that being missed here which is not letting this motor cut loose. This thing should be able to turn 5,100 or so rpm with the impeller that in the pump if I can get the last 1/3 throttle to work and for longer than a minute.
Here's all the files that go with the motor.
I don't know where to look in HPT, but here on LS1 Tech I'm reading about problems with DBW pedal position and throttle position not being within spec of each other and causing limp mode. I know with the CAI off I can see the throttle blade fully opened just past 1/2 throttle on the gas pedal travel. The motor and ECU are from a 2002 Tahoe, the TAC and pedal are from a 2001 Yukon. It shouldn't matter, but you never know.
Here's the table for the gas pedal. Is this correct? I would think it should go from 16 on the bottom to 100 on the top and be smoothed in between. But the throttle blade is open 100% at 60% pedal travel.
Here's the table for the gas pedal. Is this correct? I would think it should go from 16 on the bottom to 100 on the top and be smoothed in between. But the throttle blade is open 100% at 60% pedal travel.
Is that a stock pedal table?
I would re-build that 5.3 for marine spec..you will lock that thing up running it in that cool water.
Running that cool of temp will be making it rich as ****..you are no where near the closed loop table parameters(unless you changed that, I cant see the tune), so the O2's are pointless. At that temp it's in the command open loop settings, which at that temp are rich.
I would re-build that 5.3 for marine spec..you will lock that thing up running it in that cool water.
Running that cool of temp will be making it rich as ****..you are no where near the closed loop table parameters(unless you changed that, I cant see the tune), so the O2's are pointless. At that temp it's in the command open loop settings, which at that temp are rich.
No idea how to do a case relearn. BUT, I found the issue, or at least one big issue. The fuel pressure. It was dropping down to 20 psi. The main line out of tank had a check valve on it. Changed the check valve for a barb and now it pulls ok up to 3,800 rpm till the pressure drops off again. I'm running a Walbro pump and have it mounted up front next to the tank. Do any of you guys run a low pressure high volume pump to feed your high pressure pump on retrofits? Like say a Holley red. I was thinking of putting a low pressure pump next to the tank the move the high pressure Walbro pump to the back by the motor.
Teching In
Joined: Nov 2011
Posts: 11
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From: Big Sky Country
Blazeracer I am in the same boat ,no pun intended. I put a LQ4 in my 21' jet boat this winter. I got it out once so far it seemed to work ok its already faster than the HOG 454 I took out. I used a heat exchanger so my engine runs on the thermostat and enters closed loop also used water jacketed headers to be able to run dry O2 sensors. I haven't done any logging yet. I am kind of at a loss on where to start tuning. Keep us posted on your progress and I'll do the same. Pics would be nice.
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Verdad Gallardo Here's a few pics. I've thought about a heat exchanger. The guy that did my harness set up my initial tune and I think he took care of the temp deal. It starts reading from the O2's almost right away, like as soon as the initial startup is over. I can see the O2's and the STFT's working on the VCM scanner and all this thing has run so far is LEAN. Took it the lake yesterday but didn't bring the laptop. I did get a check engine light so I'll hook the handheld up and see what codes pop up.
Sorry I haven't updated this thread at all. Turns out all the issues this boat was have was due to fuel pressure issues. I went through two Walbro's that just wouldn't pull the fuel up and over the side of the gas tank and then push enough pressure for the fuel system. I think the real issue was in the tank itself, not the pump. Anway, shortly after my last post I went to the local junk yard and got a Silverado gas tank for $75 and put a new intank fuel pump from Autozone and wha-laa.... All problems have been SOLVED!
We just spent the entire summer beating the crap out of the boat. Was on the water three days a week and probably logged 100 hours on it. The water temps in the closed loop tables are dropped down to 110 or something like that. The lake water is at about 120 inside the motor so it goes into closed loop real quick and work perfect. I changed the impeller in the Berkeley pump to a C cut and that got my RPM up around 5,000.
Best GPS of the summer was a 58.6, which is two mph faster than the boat was with it's stock 460 Ford. Not bad for 325 EFI cubic inches. The best part is that it will go back and forth across the lake all day on a tank of gas.
Next upgrade for this boat may be a 6.0 stroked to a 427 running the Gen IV Camaro heads. Those engines are beasts!!
We just spent the entire summer beating the crap out of the boat. Was on the water three days a week and probably logged 100 hours on it. The water temps in the closed loop tables are dropped down to 110 or something like that. The lake water is at about 120 inside the motor so it goes into closed loop real quick and work perfect. I changed the impeller in the Berkeley pump to a C cut and that got my RPM up around 5,000.
Best GPS of the summer was a 58.6, which is two mph faster than the boat was with it's stock 460 Ford. Not bad for 325 EFI cubic inches. The best part is that it will go back and forth across the lake all day on a tank of gas.
Next upgrade for this boat may be a 6.0 stroked to a 427 running the Gen IV Camaro heads. Those engines are beasts!!
Here's a video. Mine's the blue and white one.
http://www.youtube.com/watch?v=ylofM...ature=youtu.be
