L31 383 No changes taking effect!
I'm attempting to tune a 383 Vortec with an L31 PCM and when I make changes to the main VE table, timing map or anything else nothing happens. For example, 2000 rpms and 37kpa is about 17/1 lean and when I add 30% to the VE table in this area, nothing happens. Are there any known problems/work arounds with these PCMs? I will be able to verify that the truck has proper fuel pressure in the morning. Any help with this would be appreciated.
:Originally Posted by greasess
Try making changes to the secondary ve table. L31 ecm are very limited..
I tried making changes to the backup ve table and nothing changed. When I get to the shop this morning I'll read the tune that's on the pcm to verify that changes are at least being saved. Then I'll make sure the fuel pressure is right. After I check both of those things I'm not sure what to look for next.
Are you getting a MAF DTC...?
I got a P1345 DTC(Cam and crank out of phase/alignment). The cam is a flat tappet for an early block which is not indexed for the CPS that is mounted on the distributor. I think this would explain why changes to ignition timing are not taking effect. At this point I'm assuming this has a lot to do with my fueling problems. I did verify that I have 60 psi of fuel pressure with the key on and engine off. I also verified that the crank and cam position sensors and reluctors are installed correctly as is the distributor. I also verified that the changes are being saved to PCM memory. According to crane cams this is a known issue although they had no idea how this may effect the L31 PCM. At this point we are waiting on the customer's approval on a new cam and retro-fit roller lifters... If anyone has any idea how this problem would effect the L31s fueling and ignition I would love to hear about it. Thanks for the replys
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