Pulling Timing Between 2k - 3k RPM Under Load

[1156248781]

I am working on my 2003 5.3 ECSB 4X4 Silverado, just installed a new Comp 265 cam (212/218 .522"/.529" on 114*) and had my factory #706 heads milled .025" for a SCR of 9.87:1.

I am still working on the VE and MAF tables (armed with the Greg Banish DVD's) and for the most part, it runs pretty well for a first timer with only a few hours of tuning under my belt.

My problem is that when I have a steady state load (going up a long hill for example) with RPM's between 2k and 3k and 50% TPS, it seems to have no power. Checked the LOG and it looks like timing is being yanked (from 25* to 3*, frames 1150 - 1200 in the LOG) and I cannot figure out why.

I previously had an issue with knock and adjusted the timing tables to eliminate this but the KR does not seem to be the cause. I know its probably a simple answer (thinking burst knock form what I have been reading) but am not familiar enough with this yet. I thought about modifying the PE tables a little more, but don't think PE should be that easy to enter from cruise mode, if that makes sense.

I am including the LOG, tune I have been working on, and the stock tune for comparison. Thanks in advance for the help!

[1156248781]

Ok, I have adjusted the BK tables from 0.015 to 0.030, copied the high octane tables to the low octane tables, and still have the same problem. When driving, as you start up the hill (I have a large mile long hill preceding my house) and as I begin up this hill from the stop sign, it starts well and in second gear it will hesitate once right at 1800-2000 RPM's and then have problems from that point on.

It is not KR, and I do not see any additional modifiers available. I am running 0.0* - 5* under load (sometimes it runs into the negatives). Don't really know what direction to go on this at the moment especially since the advance tables are actually less aggressive than the stock curve. HELP!!!

[04SilveradoMykk]

Under engine>torque management > General> Max Torque to 640. and the rest of the tables under it to something like 40,000,000

Max torque vs rpm, all to 640

ETC Limits, ETC TPS Max, too 100% across the board. ETC injector disable all to 255.

I'm not saying this will get rid of your problem, but will remove the possibility of torque management pulling your timing and closing throttle.

Than log with an ignition timing .cfg (like the one I attached below) in your scanner to see exactly where your timing is going, and where timing pulls are coming from.

Also, in your Progress 2 tune your running 2-5 degrees less timing than stock, that can make for a lethargic acceleration rate too.

I really don't like the ignition timing map, stock... there is no reason you should be running that low of ignition timing around 1600+ .64g/cyl+

Zero out the Spark Correction>AFR correction tables. And use a timing table similar to this:

[1156248781]

Thanks for the info SilveradoMykk, I will put these changes into effect. I cannot use your config file at the moment since it was created with a newer version than I have, and HP Tuners customer support has yet to grant my request for the updated scanner and Beta editor.

Question regarding the new versions, if almost everyone has it already, why isn't it available for download? I really do not understand having to wait until someone gets to my request (the second request has been sent, never got a response on the first one either) to get something that is apparently commonly available. Very frustrating.

[1156248781]

Got everything changed as directed and have been putting a few miles on it, I would have to say it is 90% cured at this point however I am still getting some surging/hesitation under load and 50% throttle. I am also now getting a MAF performance DTC periodically, could this be related to the change in timing?

[04SilveradoMykk]

If you could, do another log with your current tune while the truck is hesitating.

At this point I would spend more time tuning VE and MAF tables. Refer to the write up's here on HPT forum for the how to.

Cheers ~Mykk

[1156248781]

Mykk, thanks for all of your help so far, very much appreciated! Anyhow, I found a problem where I have a slight exhaust leak at the driver side manifold, so I have headers on order and will start from scratch using the timing tables you have provided as a baseline. Going back and looking at my tune, it looks like I am way fat across the entire VE tables for having only a cam and everything else stock when comparing other tunes.

Question about the MAF tuning, in watching the Banish DVD, he said that MAF tuning should be done when the intake track is modified from stock. Looking at a 6.0 2500 HD tune, the MAF tune is the same as the 5.3 1500. Is this correct? I know when I did my VE tables the LTFT's were still way out until I fattened the MAF tables. Again, not questioning the need to do this, just trying to better understand the principles/theory behind everything as I have read of people just doing the VE and retaining the stock MAF value's.

Thanks again!

[04SilveradoMykk]

Please don't take my advice to be the answer all/end all in your tune. Experiment around and you may find your truck likes more or less timing in certain ranges

Unlike the performance and racing world of carburetors these genIII/IV LSx engines make more torque and horsepower with ignition timing several degrees sooner than just before detonation