struggling with e38 speed density start up and idle

[walkerwilkin]

Im having issues with my 2008 Silverado 4.8l rclb wt with sloppy stage 2 cam (228/230 .585" lift), vsracing 7875 turbo, 75.5# decapped injectors, and efisource 3 bar map. I am still learning hptuners and decided that using a base tune from the sloppy tune cabinet would get me off to a good start on tuning my truck. i used the tune from Matt's wife's truck that is almost identical to mine except for the turbo. I upgraded to the 2 bar speed density os and used copy over all differences from matt's tune into my own. This tune will barely start the truck unless I pump the throttle and the idle surges from about 400-600rpm and dies after about a minute. After messing with the tune for a while i decided to attempt populate my own ve table with the same result and unable to bring idle rpm above 500+. im pretty sure my maf is failing properly. Does anyone have any advise or helpful howtos? Any help would be appreciated. here is the file. slopptune##.hpt

[sevinn]

I think one of your issues may be with your injector flow rate settings. If your injectors tested around 75.5, that's what the flow rate should be in the ~400kpa area in the flow rate vs delta table, but you still need to scale it out for the vacuum drop if you're running a returnless setup.

Also, what's your map say at koeo?

[chemical]

the map on Matt's wife's truck is for a duramax. I think efisource map linear 305.00 kPa , offset 10.33 kPa.

[walkerwilkin]

I think one of your issues may be with your injector flow rate settings. If your injectors tested around 75.5, that's what the flow rate should be in the ~400kpa area in the flow rate vs delta table, but you still need to scale it out for the vacuum drop if you're running a returnless setup.

Also, what's your map say at koeo?

I have changed my flow rate by maxing out the flow rate vs pressure table at 63.5 and using the voltage multiplier to bring the values to 75.5 with little change. I assume i shouldn't have done this for all values with a returnless setup? Should i use values that ramp up to my flowrate at lower pressure delta? My map says 105 at koeo.

[walkerwilkin]

the map on Matt's wife's truck is for a duramax. I think efisource map linear 305.00 kPa , offset 10.33 kPa.

yeah he says duramax in video and efisource in wiki lol. ive tried both, I need to leave it at 305/10.33 for consistency's sake because im sure this is a culmination of issues.

[RySmDPT14]

Have you tried increasing the idle to 800 or so to keep it running. My truck idles at 900 rpm any lower I get misfire codes. That’s where I started as well as used a stock ve table to get running.

[walkerwilkin]

Have you tried increasing the idle to 800 or so to keep it running. My truck idles at 900 rpm any lower I get misfire codes. That’s where I started as well as used a stock ve table to get running.

It doesn?t respond to changes in base idle as far as I can tell

[sevinn]

I have changed my flow rate by maxing out the flow rate vs pressure table at 63.5 and using the voltage multiplier to bring the values to 75.5 with little change. I assume i shouldn't have done this for all values with a returnless setup? Should i use values that ramp up to my flowrate at lower pressure delta? My map says 105 at koeo.

Correct, with a returnless setup you need to keep the ramp in place. Try scaling them to where the ~400 column is near where you want then either use that voltage multiplier or do the double stoich/half ifr method to get it right. 105 is probably reading a little high but it shouldn't throw you off that far.

Log desired idle speed to see if it is actually responding to your requests or not, but I think if you get the injectors closer you'll be in better shape. You may also need more base airflow. What size throttle body is on the truck?

[walkerwilkin]

Correct, with a returnless setup you need to keep the ramp in place. Try scaling them to where the ~400 column is near where you want then either use that voltage multiplier or do the double stoich/half ifr method to get it right. 105 is probably reading a little high but it shouldn't throw you off that far.

Log desired idle speed to see if it is actually responding to your requests or not, but I think if you get the injectors closer you'll be in better shape. You may also need more base airflow. What size throttle body is on the truck?

ok I have the injectors setup more appropriately with no noticeable change in idle quality or speed. I logged my desired idle rpm and it was sitting at 800. I changed my idle rpm in tune and it displayed higher with no change whatsoever to the idle. I have the stock 87mm drive by wire throttle body. At my 600ish rpm idle my map is reading 85ish and the timing was around 30* which I thought was kinda high? I lowered it to 22* with no change in idle again. idle is sitting around high 12's low 13's afr. the idle is very delicate. It will not start unless I depress the throttle and will not idle until I gently set the rpms into the 1000-500rpm range with the throttle. if I rev at all it will fall and die or barely catch itself. I hope some of this info helps.

[walkerwilkin]

OP here. Figured it out. Under idle>airflow>effective area>max fail and percent max. I just maxed them both out and it actually started correcting my idle. I guess the drive by wire throttle was unable to get any movement to correct the throttle because I was failing the maf. Not sure if the percent max was restricting me but I maxed it out just to be sure. Idle and startup are no where near perfect but I can actually start to dial them in now lol.

[rodstrong0]

hey what were the max fail numbers and percentages