start and idle problem

[shinyrust]

Attached is the log I just pulled. about 2 min long. it fires up without hitting the gas now but it hunts hard to the point it almost stalls. I adjust the TB stop and it is either too much or too little. it will either start and run great then high idle like no other or start like crap and idle well when its warmed up. then if it shuts off it and i go to restart it acts like it has a lot of timing. like a small block with 13 to 1 compression. Any guidance is welcomed!!idle tune.hptrough start up and idle.hpl also right now while idling the WB is reading .86 lambda.

[5FDP]

I can't view the tune but what are you asking for idle timing. What are you tables setup like?

Most LS's with a mild cam or stock cam prefer 18-22 degrees of timing with some larger cams in the mid 20's.

[shinyrust]

I think i have it attached now. I believe that I have the start up around 15 and idle around 23.

I have a tsp truck cam stage 3 218/220 111 lsa and 550 lift. so there is no overlap. but a good amount of duration. I also installed a trailblazer ss intake with the ss factory injectors. They are the 30# injectors. I tested my fuel pressure and it is at 60# all the time (dead head set up/ returnless). The motor is a 5.3.

[shinyrust]

5FDP, you must be the only savior at HP tuners forum. You are the only one that replies to my post LOL

[shinyrust]

Here is what I ended up with after driving for a while.

[5FDP]

What happened to the base running airflow table?

Why does it shoot way up to 315 at 90 degrees and that is kinda where you are starting it.

That is not helping you at all. Did you attempt to use any of the idle airflow tuning stuff around yet?

[shinyrust]

I tried to find the Russ K config and the best I could find was to shut off LTFT and graph idle desired. when that graph is full copy and paste. then turn on adaptive idle and everything else. I haven't found anything else that spells it out how and what exactly.

[lukearmstrong1990]

halving start up flare control spark values will help

zero out the stall saver values as they send you on a wild goose chase.

car needs more air by the looks. its also quite rich idle going off o2 mV

[shinyrust]

By more air do you mean open the throttle or add it in the tune?

[TCSS07]

your base airflow table needs some work for starters heres a idle write up i found that may help you out
https://forum.hptuners.com/showthrea...e-(w-pictures)

[lukearmstrong1990]

more air if your IAC counts suggest the motor can add more, otherwise yes open throttle stop and re-calibrate 0%

[shinyrust]

yeah I am at a loss right now. So I drove the truck to work so I can do some logs. Before I started the drive home I adjusted the throttle body to add air so that the truck will start easier and stay running. It always wants more air... So obviously it is idling a little high and I drive it home. It is idling at 1500 when rolling. So I when I get home i adjust the stop so that the IAC motor has a value around 50. But it moves so much it drives me nuts, any change in the stop will cause a HUGE change in the IAC steps. I am guessing that it is because of the Cam that it moves so much. So if I can get it to idle ok then I will call it good.

Next step is trying to figure out how to get my VE tables out of the 100's. It cant be right at all. I don't know of any motor that has over 100% efficiency starting from the 2500 rpm range clear past the 4000 rpm range. Wide band reads .96 to 1.03 or so all the time. When I mash the gas I get some spark knock in the 2500 and 4500 range at about 90 to 100 kpa. I can not wait for the Ah HA moment to hit me.

[cobaltssoverbooster]

Ve table does not represent percentage of efficiency. In fact it doesn't represent anything definite. All the gm ve numbers are is placeholder values in which you can make changes in percent to. Don't let their value confuse you because that's not indicative of it's efficiency.

[lukearmstrong1990]

RPM hanging can be rectified by the throttle cracker airflow table and the throttle follower decay table.
it can also be "cheated" by reducing spark in that area significantly in the appropriate table. if you have rev hang at 1500RPM on coast down at speed then log the timing. it will likely be over 28degrees. this is usually in the logged RPM column somewhere in the 0.08 to 0.20g of air. reducing this in either the main or idle spark tables (depending which one its running off at that point) to 6-10 degrees can be enough to make it stall. so finding the happy medium to pull the coast RPM down fast enough without stalling will generally be a value between 8 and 16 degrees.

your KR is because your PE enable requires 90% or greater throttle to add fuel. set that much lower so you can be in PE mode during medium to high load acceleration. the extra fuel to a 12.5-13.0 (depends on combo) will stop the KR.

[shinyrust]

So correct me if i am wrong. Adding to VE will make the air fuel ratio leaner

[lukearmstrong1990]

increasing the VE numbers adds fuel because it commands more PW

[cobaltssoverbooster]

its an airflow table. it models the amount of airflow the engine is getting. if you add more you tell it that its seeing more airflow which in turn commands more fuel.

[shinyrust]

thank you all for saying it in crayola so that I can understand. Couple issues that are also haunting me is:

that I will log my O2 and my wide band and they never line up. The more I increase the values in the VE table the closer they are getting but thats only on the extremes. so 1.25 lambda and 0.136 mV

It takes 50seconds to 70 seconds for the STFT to kick in upon start up and assist with the idle to be somewhat stable. Where can I make adjustments for that? so that the fuel trims kick in sooner

My truck runs better at this point if I fail the MAF. So I am guessing that my VE table is ok and I need to work on the MAF calibration and circle back to Idle?

Dont know if any of yall are in the baltimore area but Ill buy you a round for all this help I received so far. Knowledge isn't cheap, I know that!

[shinyrust]

latest tune and log from this morning.

MAF set to fail and made adjustments to the start up and no luck so far.

[shinyrust]

So I started over. If anyone can take a look and point out any shortcomings in the idle tune it would be greatly appreciated. It idles ok but now when I go to slow down or coast it hunts for the desired idle rpm to the point it wants to shut down. I also still need to hit the gas to get it started until it can sort itself out a bit, then it is fine.