LS1 243 Heasds 244/244 Cam Idle Tuning

[swla71276]

Just looking for guidance... 1999 C5 FRC LS1. Purchased this car with all these mods. Long tube headers, ported 243 heads, 244/244 cam 610 lift. No cats. 3 inch exhaust all the way back. The issue im having is idle. Actually the car starts up well when cold. idles well for the first 2 or 3 mins. Seems to get progressively more and more rich. To the point that the car is blowing black smoke out the back...quite badly.. after ect temp reaches 140F or so. Any ideas? i thought about possibly a drippy injector or other mechanical issue. Whats a cpl good places to look in the tune file? its set up as Speed Density by the way. It was already that way when i got it. MAF is completely removed from vehicle. All EGR/smog components removed. ACT sensor in filter housing. Stock TB. LS6 intake. Stock injectors.

[blindsquirrel]

Closed loop is not likely to play nice with a cam that big. The misfires at low speed that are inherent with big cams gets picked up as a lean condition by the O2s, and it adds fuel, which doesn't make it stop misfiring, and it keeps adding until trims are maxed out.

[5FDP]

If you ask me, you shouldn't really do any tuning until you get larger injectors. There is no way that the stockers will be big enough for a camshaft this size.

You'd have to redo everything anyway.

Also if this is speed density only, apply the 1 bar speed density OS enhanced in the OS tab. Save under a new name and write entire. That will remove the secondary VE table and make tuning easier.

[swla71276]

If you ask me, you shouldn't really do any tuning until you get larger injectors. There is no way that the stockers will be big enough for a camshaft this size.

You'd have to redo everything anyway.

Also if this is speed density only, apply the 1 bar speed density OS enhanced in the OS tab. Save under a new name and write entire. That will remove the secondary VE table and make tuning easier.

Im not necessarily sold on being speed density. This initial tuning was done by the previous owner. Any benefit to going back MAF? or do you guys think speed density is the way with a cam this big?

[blindsquirrel]

Do you think the airflow is stable at low speed with a cam that big? MAF is not the way to go, either. For many of the same reasons as closed loop.

If you want something able to use all the benefits of the factory PCM, put in a cam under 230*ish intake duration. If you want a race car, go Holley or Haltech or something meant for that. Sure, lots of people are running their race cars on stock PCMs, but they probably shouldn't be.

[SiriusC1024]

Try this real quick. Run a compare and look through it.