anybody have a GOOD file for an LS376/480 crate engine?

[DSteck]

A local guy is building a Factory Five GTM using an LS3 engine. It's the GMPP LS376/480 with the supplied PCM. It doesn't want to start and stay idling, and if you rev it, it wants to die. I made some adjustments like I do with any cammed car I do, but this thing just doesn't seem to like the adjustments, and I'm absolutely puzzled by this thing.

It didn't help that the alternator wasn't hooked up to charge the battery though.

Anyway, has anybody had an issue with the GMPP LS376/480 PCM just being garbage for startup/idle stability? I had it starting and idling rock solid, and it had perfect recovery, but just went to shit after the battery started crapping out.

Unfortunately we can't drive the car yet because it doesn't have seats bolted in or any glass. Haha.

[ou8spam2]

I know I haven't posted much but I do know that if the voltage drops below I think 10.5 everything goes crazy with the computers. You might want to hook up the alt before trying anything else.

[IDRIVEAG8GT]

I know I haven't posted much but I do know that if the voltage drops below I think 10.5 everything goes crazy with the computers. You might want to hook up the alt before trying anything else.

Agreed, oh also, a vacuum leak could be a major factor as well. ECM requires some odd 15 inches of vacuum to be happy. If not, the computer will whack out. The rumor is if you do this long enough, if the vehicle has the option, it will notify OnStar. Go figure!

[DSteck]

The owner told me that after properly connecting the alternator, it fired right up perfectly.

Now we just need to keep it alive... that Tilton clutch just has no weight to keep the engine spinning after a rev.

[midgetracr]

Just PM'd you a .hpt file that runs my LS376/480 quite nicely.

John

[Chevy406]

John or DSteck - can you also send me your .hpt file for the LS376/480? I am helping out a friend with a '67 Corvette build, and his LS3 is also struggling with idle surge.

Last night I added a little airflow (ECT Mult) table and I reduced the Idle adaptive spark over/under speed. After some reading today I recognize that I should have probably left the spark table alone and datalogged the RAF before anything else. His car does have an exhaust leak which shows up on the Bank 1 fuel trim, so he is working to remedy that.

[edcmat-l1]

The calibrations that come with those engines and controllers suck. I've tuned quite a few of them. I know I'm going to sound like a broken record, but I tune them in SD.

[DSteck]

It works a lot better in SD, in part because the intake tubing setup on the one I was working on was ridiculous. I never finished it though because the owner has been out of the country... Plus, somehow the PCM is corrupt and reports stoich AFR as something crazy.

[edcmat-l1]

It works a lot better in SD, in part because the intake tubing setup on the one I was working on was ridiculous. I never finished it though because the owner has been out of the country... Plus, somehow the PCM is corrupt and reports stoich AFR as something crazy.

They all work better in SD.

[DSteck]

Just to add, the injector data is totally effed in the LS376/480 calibrations.

[Chevy406]

Sounds like I'll give it a go with a SD tune. The car isn't driveable just yet, but hopefully I can get enough data to get a stable idle. The builder is trying to have it ready for a show in Nashville either next weekend or the following weekend.