Problem Tunning For New Cam

[Chalky]

Whether you have the cam in +4 or -4 degrees, it should still run and idle ok depending on cam. 4* +/- is in the realm of possibilities assuming cam is ground straight up. Are you sure the dots were lined up on teh timing gears?

Have you ruled out a vacuum leak? The runner gaskets on the LS motors can slip.

If truck is in OLSD, let it warm up, log AFR commanded and actual, timing #1 cyl and KR. Also capture Man Pressure in KPA.

[Chalky]

You are right. I just found a tun file for a 2002 5.3 and the IFR table is a fixed value.

??

[dfe1]

You are right. I just found a tun file for a 2002 5.3 and the IFR table is a fixed value.

??

The reason that the IFR tables for Corvettes, Camaros, Firebirds and some other vehicles have scaled vallues, is that these vehicles have a "returnless" fuel system that does not include a pressure regulator that is referenced to manifold pressure. On the other hand, most trucks have such a pressure regulator so there's no need to create an electronic reference to manifold pressure-- the regulator has a direct reference. Similarly, if you were to install a manifold pressure-referenced regulator on an engine not originally so equipped, you would change the IFR table to a fixed value.

[Chalky]

OK. just an idea after looking at VE table. have you tried a stock VE table and just adding 15-20% to all values and then trying it again?



If that is a valid VE table based on AutoVE? Max values @ 1600 RPM?

I would think that these would be signs of an overly advanced cam.

There are some builders/tuners on the forum. Howard @ Redline Motorsports might be better able to help.

Good luck. I hope you get it running to your satisfaction.

[Chalky]

The reason that the IFR tables for Corvettes, Camaros, Firebirds and some other vehicles have scaled vallues, is that these vehicles have a "returnless" fuel system that does not include a pressure regulator that is referenced to manifold pressure. On the other hand, most trucks have such a pressure regulator so there's no need to create an electronic reference to manifold pressure-- the regulator has a direct reference. Similarly, if you were to install a manifold pressure-referenced regulator on an engine not originally so equipped, you would change the IFR table to a fixed value.

Thanks for the info. I didn't know GM was still using a regulator. I assumed all were just returnless systems like Vets/F-Bodies.

can you think of anything that would cause his VE table to peak @ 1600 RPM outside of an overly advanced cam? The VE max numbers seem OK, just peaking way to early. With an overly advanced cam would come an increase in compression which could account for the KR so early.

[dfe1]

Thanks for the info. I didn't know GM was still using a regulator. I assumed all were just returnless systems like Vets/F-Bodies.

can you think of anything that would cause his VE table to peak @ 1600 RPM outside of an overly advanced cam? The VE max numbers seem OK, just peaking way to early. With an overly advanced cam would come an increase in compression which could account for the KR so early.

I don't think this is a tuning issue. The cam isn't radical enough to require any changes to a base tun file for the engine to start and run decently. Tuning will certainly optimize performance, but if extensive changes are required, or if air/fuel ratio is whacked in some areas, other things are going wrong. Judging by the VE table, that's the case-- the spine at 1600 is more than a little strange. You may be right in thinking that the cam isn't installed correctly. For what it's worth, any time I've had to work over a VE or timing table to the point that it looked wrong, in order to get an engine to run decently, there's been a mechanical issue. Once the mechanical issue was corrected, the engine would run fine with tables that looked right.

As a general rule, it's best to make one major change at a time. It would be easier to troubleshoot if the truck still had a functional mass air sensor. That way, you could load an LS6 cal and if the engine had the same problem, tuning would obviously not be the issue. Also, if the OS was changed from a 2000 to a 2002, you have to question whether the conversion was done properly. Again, if the MAF was functional, you could reload the original 2000 tun file, cut and paste the LS6 VE tables and see if the problem still existed.

[shakinlm7]

I had tried starting over with a fresh 2000 os off of the tun repository. I ran it through the autoVE tutorial, logged a couple runs updating the VE table every time and it did the same thing as its doing now. I'm going to give roller master a call today and hopefully they can help me verify whether its installed right or wrong.
Thanks Again Guys!
Happy holidays!

[shakinlm7]

I finally found some info on rollmaster timing chain installation!! Looks like I actually retarded my cam. Hopefully it will work out!

[5.7ute]

I dont want to sound like a smart ass here but a simple check with a degree wheel would of found this issue upon install.

[shakinlm7]

I don't want to sound like a smart ass but you definitely just sounded like a smart ass