shizzle24

iTrader: (1)

I have a 2000 automatic LS1 freshly rebuilt (~30 miles on it). New acdelco cam sensor and crank sensor. New cats, new Bosch o2 sensors. New acdelco knock sensors

Mods:
-GM hot cam kit
-long tube headers
-full exhaust
-tuned by frost


I also deleted the air box and rear o2 (tune to accommodate deletions).

Symptoms:
-rough idle
-occasionally stalls if medium throttle to brake (braking for a stop light)

What I've done:
-cleaned iac
-cleaned maf
-idle is set to 750 rpm
-fresh gas (sat for a few months while I rebuilt motor)
-no check engine light (nothing pending)

shizzle24

iTrader: (1)

Hptuners

http://s578.photobucket.com/user/shi...08051.mp4.html

2xLS1

iTrader: (25)

Stock converter? GM Hot Cam and a stock torque converter is a bad combination. Not sure what you were expecting with a Hot Cam but it will have a choppy idle. Have you contacted Steve for an updated tune for those problems?

shizzle24

iTrader: (1)

Yes stock converter. Not to concerned about the choppy idle. I wanted something one step above stock. I thought the stock converter was ok, apparently I think I was wrong . I have not contacted Steve to get an update because I have been trying to make sure it wasn't a bad sensor or something wrong mechanically. I think I'll get a new torque converter. I'm thinking about the Yank ss3600. I've seen a lot of people say they are good for a DD.

JakeFusion

iTrader: (7)

Sounds like you have an airflow issue in the tune if it stalls.

Rough idle? Can you describe that? Cammed cars idle rough.

Streetracer09

iTrader: (1)

I have a similar issue. I'm not stalling but it will run smooth for a few seconds and then start shaking the car a good bit and then clear back up. I've had other cammed LS cars before that had choppy idles but didn't shake the car like this. I'm going to mess with the airflow at idle and see how that works. Good luck I am subscribed.

silvershark

If this is the standard hotcam ground on a 112 lsa in an automatic on a stock converter, you are going to have some issues at idle... Nothing major that can't be helped with tuning. First, up your idle to around 850rpm, second I noticed your timing is around 20-21, change that to around 24-25.

Start there and see what happens.

My cam is on a 115LSA and I currently am running my stock converter and had the same issues until I upped my rpm's at idle and adjusted timing. You may need to idle around 900rpm due to the 112 LSA on that cam. With upping the idle you are going to feel like you are pushing through the brakes (feel like a cruise control effect). Nothing you can really do about it other than lower the idle. I would even suggest upping your idle to around 950 so you aren't fighting the stalling issue, then you can look at your VE tables and EQ tables and get it tuned correctly. Once it's tuned correctly then you can lower your idle.

Basically whats happening is due to the LSA and cam duration at 750 rpms your car isn't creating enough vacuum and causing your car to stall... It would be much like creating a vacuum leak in your system and expecting your car to run fine. Hopefully that simple explanation makes more sense..?

Whats your commanded AFR, I assume 14.67?

What's your EQ table look like? Engine>Fuel>Open and Closed Loop>Open Loop>EQ ratio

I assume you do not have a wideband?

mrvedit

silvershark: Excellent post and suggestions! Seeing that you have been a member for 10 years and have so few posts (27 today), I can only encourage you to become more active and share your wisdom.

Maybe you are becoming more active here because its getting dark in Alaska?

Darth_V8r

iTrader: (4)

It is a vacuum leak at the valves. The faster the engine revs, the shorter the duration of overlap - when both valves are open at the same time. So, when you increase the RPM, the overlap time (in milliseconds) decreases.

silvershark

Winter does play a role. I used to be REALLY active on "the other z28 forum" many years ago as I owned a LT1 back then. Just getting back into the fbody scene again. After selling my LT1 I purchased a few other ford sports vehicles, finally decided to leave the dark side and get an LS1.