Little surging issue

[picnic_george]

OK I'm not sure if this should be in gen 3 or 4 but since the OS is gen 3 I figure this would be the best place. What I have is a sand rail with an ls2 engine small cam COMP 222/224 112 lsa but the pcm is out of a 2000 5.3 silverado with a painless harness. I used custom OS and used an old tune from an 01 trans am I had. Anyways figured out what the stock injector size was set that, used the stock timing tables from a z06 and really just needed to get the car started before I start messing with everything else. Figured that would be close to start it. As well it is, the rail starts and purrs like a kitten. Turned the idle up a bit and it just sounds like it should. Only issue is when it's all warmed up we had a couple times when we cracked the throttle it would idle down just fine but after a couple seconds it would idle down a little low and surge for a few seconds then correct itself. This only happened a couple times most of the time it was fine. Maybe a the ecu still needs to learn I won't try to pass myself as a anywhere near a pro here. I'm super basic but I'm learning.
The vehicle does have power steering that may make this issue even worse when we finally get it out to check the wideband and start running the thing.
I've done a lot of reading and searching here but it get's a bit overwhealming. I don't know where to start. Maybe you guys can take a look and make some suggestions or even make a change for me so I can see where I should be looking.
Thanks for all the help
Kris

[picnic_george]

Should I maybe try posting this somewhere else?

[5.7ute]

Should I maybe try posting this somewhere else?

You just need to wait for the right people to come on here & have a look. Have a search on rafig, & check out the idle sticky in the tutorials.
Also have a look on the Holdencrazy site for a tune with the same cam, that will give you an idea on what timing that size cam likes at idle.
It would also help to post a log where the problem is evident.

[joecar]

Will this help: showthread.php?t=4661 (http://forum.efilive.com/showthread.php?t=4661)

[picnic_george]

I don't think holdencrazy has anything close to what I'm looking for. I checked em over there thank you. I'll get a log next time I see the thing.


Will this help: showthread.php?t=4661 (http://forum.efilive.com/showthread.php?t=4661)Yeah I've read that and there is a lot of good info in there. I just don't understand what half of it means hahaha. Maybe I just wanted someone to tell me how messed up this tune looked or some things that they think may need to be changed/looked at.

I assume I need to just spend a lot more time on it.:rockon: It's overwhealming though I'll admit it.

Thanks for the replies

[joecar]

Take it step by step, ask questions as you go, the more time you spend on it the easier it gets... :)

[SSpdDmon]

Personally, I probaly would have started with an f-body tune ('99 model year) and use the correct injector tables. From there, you'll have to alter the displacement, kill all of the sensors that aren't hooked up, pull timing in the lower RPM/lower gram/cyl cells, and maybe try to richen it up some where it's surging. I don't have time to look over the tune, but a small cam like that in a 6L shouldn't be too much trouble. You're probably feeling the effects more because it's in a 1500lb vehicle instead of a 3500lb car.

[picnic_george]

Haven't felt anything cuz it hasn't been driven yet. I can use a stock 99 tune if you think that's better. Any reason it would be better than an 01 tune?

How do I change the displacement? I haven't found how to do that, I didn't know there was an option for it.

Do you think something as simple as an autove will get it right?

Thanks for the help:rockon:
Kris

[SSpdDmon]

B0104 = cylinder volume

The timing map in the '99 will be closer to what you end up with than using an '01 table. You can try starting out with timing similar to what I had in my h/c car.

[picnic_george]

Will do, thanks a bunch. I'm not at my laptop right now, when I adjust the cylinder volume does it automatically asume the VE changes?

[SSpdDmon]

Will do, thanks a bunch. I'm not at my laptop right now, when I adjust the cylinder volume does it automatically asume the VE changes?
Cylinder volume is part of the fueling calculation just like the VE table. If one is off, then the other is too.

[picnic_george]

Think I got the surging fixed really thanks to the write ups you did. Throttle response is great and really seems to run well. Being that it was -3 at my house this morning and now we're all the way up to 1* it's going to be a little while before I really get to hot rod and tune the thing.

Thanks for all the help as usual I'll continue to read and ask questions.:cheers:

[joecar]

Good job...:cheers:...keep us posted.

[picnic_george]

Good job...:cheers:...keep us posted.Will do as soon as the weather gets warm we're going to sand mountain to have a grand ol time hahaha...:rockon: