2003 Z71--How much timing advance??

kylehamilton79 · Post by **kylehamilton79** » Wed Mar 11, 2009 11:46 pm

I have a 2003 Chevy 1500 Z71 Regular Cab with a 5.3. I am using the Predator U7195. I loaded the Performance Tune and modified parameters based on what others have done on the forums. I advanced the timing 6% all the way around, removed the first two TM, quickened shifts 10%, firmed up shifts 7%, removed top-speed limiter. I checked my LTFTs and they need to be reduced -5% to be in the 0-(+2) range. I plan on re-checking them and adjusting them when the weather is warmer, since it was 39 outside when I checked them.

The truck really screams until it shifts into 2nd, then the RPMs drop to around 3K. Once it picks back up on the RPMs, it really flies again. Will advancing the timing help this at all, or will I need to adjust something different? I currently have no KR from a dead stop up to 5,600 RPM when it shifts into 2nd. No pinging either, although I'm not sure exactly what it sounds or feels like.

All in all, the truck is really fast now, and will roast my 305/50/20 Nitto Terra Grapplers to about 45 mph. The only thing that bothers me is the second gear shift when it lags for a second before it picks up speed. I would like the most acceleration I can get safely, which is why I asked about the timing advance.

P.S. Johan sent me a custom tune 2 years ago and I can't get my USB/serial drive to work without the drivers, so I am modifying the Performance tune until I get the custom one loaded back onto the Predator. Thanks for the help.

CANUCKPREDATOR · Post by **CANUCKPREDATOR** » Thu Mar 12, 2009 12:57 am

The drivers for the USB cable are critical. Where did you get the cable from? There are drivers on the Diablo site if you bought the cable through here. If you can't find drivers, might have to buy a new cable to get new drivers.

kylehamilton79 · Post by **kylehamilton79** » Thu Mar 12, 2009 3:36 pm

I bought the cable from Wal-Mart a couple of years ago, but I had my computer and cds stolen afterwards, so I am going to have to buy another cable. I actually think my truck is running better now than it had been before I unloaded the custom tune. I had been throwing SES codes every morning it was below 40 degrees and they would go away when it was warm. The truck ran fine the last few days with it being cold outside.

sickREDsierra · Post by **sickREDsierra** » Fri Mar 13, 2009 8:10 am

sounds like you have the tune dialed in. problem here is a stock motor lacking torque down low.

what i would do is raise the shift points a bit. i would shift a stock 5.3 at 5900-6000 all day. that will put you 200-300 rpms higher after engaging the next gear. also, i would raise line pressure a slight bit at the WOT shift. sounds like maybe the trans is slipping a little, or you are just shifting it at too low of an rpm

kylehamilton79 · Post by **kylehamilton79** » Fri Mar 13, 2009 12:47 pm

Thanks. I will try that this evening and tell you how it runs. The only mod I have done to the truck is a single flowmaster super 40, but it runs so strong I haven't considered anything more. It is the fastest stock 1500 I have ridden in to date. The 3.73 gears from the factory really help too, along with the stepside bed being light. Thanks again. Here's a link to the picture I have listed.

http://superbuytires.com/gallery/view/C ... ace/12656/

sickREDsierra · Post by **sickREDsierra** » Fri Mar 13, 2009 4:00 pm

no problem man. try it and see. i wouldnt steer you in the wrong or unsafe direction.

you should ride in mine

most folks have never ridden in a new truck that runs 11's and still has PS PB and a/c. still gets 15 mpg too

kylehamilton79 · Post by **kylehamilton79** » Sat Mar 14, 2009 7:03 pm

I adjusted the shift points up to 5900 and started getting some KR, and that was the only thing I adjusted earlier. I might back the timing down some and see if it goes away. I went ahead and rechecked my LTFT and adjusted it -3 on the Fuel Slope. After driving around a while, it still shows my LTFTs to be in the +5 range, so I will wait a few days and check again when it is warmer. By the way, I checked and I forgot to say in the original post that I had increased WOT fuel in the 2-4K range up 5%. Not sure if that would have anything to do with the KR. Timing is still 6% advanced.

I checked my 0-60 time with my watch and got it as close as I could and it came out to be 8.65. Not too bad for a stocker.

kylehamilton79 · Post by **kylehamilton79** » Sat Mar 14, 2009 7:05 pm

By the way, sickREDsierra, how do you like those Foose wheels? I bought a set of Nitrous 5s for my '67 Mustang and they look sweet. I really like your truck, no I haven't ridden in an 11 second new truck. The fastest I rode in was an '82 Chevy Shortwide with a 502 in it that ran in the 10.5s.

WhiteBuffalo · Post by **WhiteBuffalo** » Sat Mar 14, 2009 7:18 pm

[quote="kylehamilton79"] I had been throwing SES codes every morning it was below 40 degrees and they would go away when it was warm. [quote]

That symptom reminds me of the leaky intake manifold issue in these AVs...

.02

WB

gump2388 · Post by **gump2388** » Sat Mar 14, 2009 7:18 pm

thats a old truck its a old body style

CANUCKPREDATOR · Post by **CANUCKPREDATOR** » Sat Mar 14, 2009 7:34 pm

Don't adjust your PE tables until your LTFTs are set right and stable. When you make a change to LTFTs (part throttle fueling) they effect your PE tables (WOT fueling).
Do LTFTs first, then work on PE, then timing. Too many changes at one time will cause grief.

2003 Z71--How much timing advance??

2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

Re: RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??

RE: 2003 Z71--How much timing advance??