Which ECU?
The misfire at idle is likely too much idle timing. My 5.3 did the same thing until I went into the tables "in neutral timing" and "in drive timing" or something like that,
And changed it from the 18* the factory uses,
to a nice smoothed looking 12-13* in the 550rpm ranges.
Idles like butter now. hopefully thats your issue also.
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Oil pressure should be like 40psi most of the time, 35psi hot idle is good. Your gauge must be wrong.
I bought one also ($15 ebay gauge) and it reads "0" all the time. lol....
Dont trust cheap electric gauges!
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The timing curve is personal to the engine and based on load.
The factory curve is too aggressive already. I am surprised you aren't seeing knock. Make sure the knock sensors are working somehow...
I run about 19* total under load (100KPA), no boost, with 87 octane. I've had around 4psi of boost on 87 no issues but with 12*~ of timing.
I think 93 octane you can get away with 24-26* of timing using the low compression 5.3L engines
rarely will an LS engine prefer more than 27* of timing, this is a sign of inefficiency if it does.
from 100KPA to 200KPA I basically slope down from 20~ to about 11*.
It can be as low as 0* or even -2* of timing around 2000-2500rpm with boost. Low rpm + heavy load = very very little timing advance. Use too much timing at low rpm with boost and it will bend a rod.
Not sure if you are turbo but that is the whole point of the 5.3L engine usually...
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For cruising, Below 50KPA, yes it is very common and essential to have 35-40* of timing. Especially for cruising on the highway.
It takes data logs, time and energy to find optimal economy, it could be as much as 45* of timing. OR even 50*!
I try to keep the timing up while driving for economy, so that means 45 to 35KPA ranges for cruising around, 33-40* is normal...
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leaves the O2 and MAF off the engine. Thats how I also keep mine, you will have the most control this way.
It forces you to fine tune the engine better. Rather than rely on fuel trims.
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get the wideband data imported into HPtuners. Use the EGR or AC or something (1 wire) and analog output from the Wideband to complete the circuit. there are youtubes how to do that.
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Swap the camshaft if you didn't do it already. I think the factory 5.3L cam is the smallest cam ever put into any LS engine.
The factory springs also leave something to be desired.
I recommend 216/220 @ .050 range, around .550Lift (look up "sloppy stage 1" TFS camshaft) because it uses the slowest, gentlest ramps of any LS camshaft I've ever seen which will prolong the valvetrain lifespan (good for daily drivers, 87 octane beaters)
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couple more timing tips
1. never use the same exact value in adjacent cells. Try to make the nearby cells different, even if just by .1*
2. don't rely on knock sensors to tell you to pull timing
3. don't rely on knock sensors at all
4. Human ears cannot detect knock, by the time you hear the knock, it's too late. Knock sensors are tuned to frequency of knock that human ears cannot hear, it happens before you hear it. So try to get them working. even though they are unreliable sometimes.
5. All timing values, just like in the VE table fuel values, should be very SMOOTH. Interpolate them if necessary.
Any sudden changes from one cell to the next means the engine will also suddenly change when it moves through that cell (the engine won't respond "smoothly")
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good luck and I am not at home or I would open your map or provide better pictures of what I am saying.
Edit: I do have this i can share, its not much but its something to look at for example
First, this is how you should be logging wideband air fuel ratios using HPtuners:
Next here is an example of "Afr advance" a table which modifies the timing based on commanded a/f ratio:
So the two things I want to point out is that the fuel target for N/A engines (100kpa) is around 12.5:1 air fuel ratio,
And the smooth timing transistions that should be apparent when looking at the second picture, and notice how peak torque regions (4800-5500rpm usually) have the least amount of timing (highest cylinder pressure = highest VE = highest Torque = lowest WOT timing)
Also in sig is my build thread, it may answer some other question you have...
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Originally Posted by kingtal0n
