5.3l absolutely no power???
05-06-2015, 12:38 AM
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5.3l absolutely no power??? Hello I really early swapped a 5.3l from a 03 avalanche into my car with a t56 anyway the swap is now running and is drivable but it has absolutely no power what so ever. I'll I can really do is idle it through each gear when u Rev it is very slow to climb in ram and the higher the rim the less it seems to pull. The strange thing is it idles awesome no misses in neutral and you can Rev it up and it responds very quick and sounds clean. The only thing is I have open headers on it and I know I need to put at least 18 inches of pipe for the o2s but that wouldn't kill the engines power like that would it? Also I have verified I have correct fuel pressure at 55psi and I threw on a brand new map sensors. Any ideas? Thanks in advance
05-06-2015, 06:35 AM
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I know you checked fuel pressure, which you probably did in the driveway. Did you check it while driving? I've seen fuel pumps pump ok when sitting in the shop, but take a nose dive when the rpm comes up.
05-06-2015, 07:08 AM
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To answer your question no I haven't checked it while driving but I will. Though I did check it in while holding the rpm up and it seemed to hold steady and come up when revved
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05-06-2015, 11:35 AM
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Well I recently pulled of the rails and soaked all the injectors in seafoam for a couple days when I was hunting a missfire at idle. And they looked great before I soaked them but the car seems to idle perfect and Rev in neutral without protest. It just seems to have no power at all when trying to pull
05-06-2015, 03:41 PM
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Don't know anyone with hp tuners but I did check the codes and I have one pending codes with is a po332 which is a knock sensor code could this be caused from open headers?
05-06-2015, 03:44 PM
#12
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A bad knock sensor would cause issues with drivability.
I ran LS engines open header before I could get the exhaust done and they ran like total ****. Getting the exhaust on helped 100%
I ran LS engines open header before I could get the exhaust done and they ran like total ****. Getting the exhaust on helped 100%
05-06-2015, 10:55 PM
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i have a question for anyone who can answer it which may be related to this topic. if the swap that he described is done,(lm7 engine that now has a manual trans rather than 4l60e) will the pcm need to see an input for the trans in gear to operate? i assume the pcm adjusts timing with input from the MAP, and is possibly not adjusted because of no input or lack of a tcm? any thoughts?
05-06-2015, 11:24 PM
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Thanks for the feedback guys!! anyway I am located in Chattanooga Tennessee and the only tuner i know of is about 30 min away and hes booked up for a couple months so looks like I am on my own lol. Anyway when I got my computer flashed this is what the tuner at lt1swap.com said."vats removal is no problem. manual trans, and performance tune for stock engine all no problem." so i think he supposedly took care of it.
05-07-2015, 09:21 AM
#16
The engine will run fine without a trans or tcm attached, electrically. Likely he shut off all the trans codes if he kept the automatic file. He really needs a data log to see what is holding the motor back. It could be anything from a faulty engine coolant sensor, bad tps or low fuel flow under high load conditions.
Need more data before changing any parts.
Need more data before changing any parts.
05-07-2015, 01:35 PM
#18
No. I have tried those and over half of them never even function especially the Bluetooth ones never connect to the car. I still recommend a data log with hptuners or efi live so you can really see what is going on with timing and fuel and see each sensor data being fed to the PCM.
05-07-2015, 02:02 PM
#19
No. I have tried those and over half of them never even function especially the Bluetooth ones never connect to the car. I still recommend a data log with hptuners or efi live so you can really see what is going on with timing and fuel and see each sensor data being fed to the PCM.