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View Full Version : Hard start condition with 5.7 in 2000 S-10



lowriders10
May 29th, 2010, 12:39 PM
First, thanks to everyone who helped me get this far. It's really opened my eyes to the potential of this software! I've gone a long way in the last couple of weeks!

I've put a 1998 Vortec 5.7 into my 2000 S-10, and I upgraded to the 0411 computer. With regards to the engine, the only major change to stock I made was the installation of a Comp Cams Xtreme Energy Kit (includes all valve train components) and a custom exhaust with Hedman Headers. It is otherwise stock.

I have a small problem with the truck engine only at start for about 10-15 seconds. It starts right away, but the RPM's fall to a near stall condition, and it revs up and down from normal idle to near stall for about 10 seconds. I can give it gas to bring up the RPMs, and it usually evens out pretty quick.

This 0411 computer was already from a 2002 Chevrolet Express with a 4l60e, so it was a direct swap in. I had this start condition with that tune, but since several Serial Data items weren't working (PRNDL to name one), I made a custom tune that came from a 2002 S-10, and then put the 5.7 data from my original 0411 PCM into that tune. I changed a couple other things (rear axle, transmission shift points etc), which fixed my Serial Data issues.

But the start condition persists. It's throwing misfire codes, but if I clear the codes after the engine starts, it's all good.

I suspect the issue is the camshaft. The Comp Cam's lobe lift is .325/.33, while the factory is .274/.287 The manual for the Cam says you will get the best results with computer tuning.

Can someone point me in the right direction to tune the computer with my engine setup? Is there a way to monitor what is happening and modify the tune to allow the engine to idle properly right from the start?

Thanks a lot for all your help!

Bill.

ChipsByAl
May 29th, 2010, 01:16 PM
What kind of duration @ .050" and lobe separation are on the camshaft? These numbers will matter more than the lift. Using one of the AutoVE methods will help reel in the idle quality and make it easier to work your current start up concern.
Al

lowriders10
May 30th, 2010, 12:46 AM
According to the Cam sheet, my duration at .050 is 212/281 (intake/exhaust), but I couldn't find the lobe separation on their sheet. Would they call it something else? Their sheet online is at http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=194&sb=2

I'll do some research today on the AutoVE to see how that works, and try that out. Thanks!

joecar
May 30th, 2010, 07:23 AM
If the LCA value 112 is for both lobes then the LSA will also be 112... (the ICL being 108 means both lobes are advanced 4).

$0.02 :)

lowriders10
May 30th, 2010, 11:56 AM
If the LCA value 112 is for both lobes then the LSA will also be 112... (the ICL being 108 means both lobes are advanced 4).

$0.02 :)

Thanks for the input, but I'm very new at this. What do all these terms mean, and where do I change them?

Bill.

joecar
May 30th, 2010, 02:56 PM
I just now read that lobe center angle (LCA) is another term for lobe separation angle (LSA), this is what you were looking for.

ICL is the intake lobe angle of the installed cam... 108 is 4 degrees earlier than 112 so cam is installed advanced.

ICL+ECL = 2*LSA, where ICL and ECL are from TDC (on either side of TDC) in crank degrees, and LSA is in cam degrees,

Have a read thru these:
http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html
http://www.small-block-chevy.com/cb_1.htm
http://www.hotrod.com/techarticles/engine/cam_lobe_centerline_angle_tech/index.html
http://www.chevelles.com/forums/showthread.php?p=2255235