running_cold924

My timing keeps jumping up and down from 8 to 14 degrees with the idle, cant get it any closer than that. The only thing I have seen that makes it kinda smooth out is by running it pig-rich (.65-.70) and I know that's not right...

Making the req fuel higher changed the frequency on the surge, made it faster.

NCLA951

What's your set up? I can look at my config. Where are you located?

running_cold924

Setup is the remnants of my rogue kit, 80 lb injectors and air filter. I have a t04e turbo, about a 60 trim, stage 5 hot side. Exhaust is 3 in downpipe and mid pipe then goes to 4. Stock internals. Til 38mm wastegate with MBC.

I am in the bottom of PA and top of MD, Cumberland area.

V2Rocket

i did the calculation (that equation somewhere) too and the number just didn't work for me.
i ended up at 12 based on advice from Peep and then my own tuning experiments.

try this..
go to the starting/idle tab and go to Idle Control, Spark cut based. disable that.
then go to the starting/idle tab and go to Idle Control, Ign. advance, enable it, and set the max advance and max retard to 4 degrees.

you might also try simple adjusting your target idle rpm up from the stock 850 or whatever it is to 1000 (idle control general)

mine also likes to idle at 20 degrees target and i have it at about .97-.99 lambda.

running_cold924

Will do, I'll give it a go. Hope for something because at this point anything would be better. I will try tonight if I can but if not probably tomorrow then.

Hopefully my email from Peep will come back with some more advice...stay tuned.

odonnell

Your timing is jumping around at idle because the load and RPM is fluctuating due to the surge. Try this... in your ignition map, find the column that's below your target idle. If you don't have a column that low, that's a contributing issue, create the column and spread out the others accordingly. Now, make that column BELOW your target something like 20* advance. Go to the next column, which should be around your target idle RPM or slightly higher, and make it slightly lower...say, 15-19*.

What happens is that when your revs drop low, the ECU adds timing and it comes back up. Think of it like balancing a marble on an upside down bowl. It tends to roll off the sides. But when you have the marble inside the bowl, it naturally rolls toward the center (target). Not a great analogy but you get the idea - you can create a "valley" in your timing table where the engine will settle into a target area. If it goes too low it will increase cylinder pressure and pop back up and you won't even notice. On the high end you're limited by air flow bypassing the throttle plate.

Auto_Werks 3.6

if your system has injector data / setup, and you ignore it and start filling in values in the VE table, you're making your life harder than it needs to be

ealoken

Why dont you just try "autotune"
And on low revs no boost make afr target 14.7.

running_cold924

The timing trick sounds like it should do what I need, I didn't think of that. I will see what happens tonight, ran out of time on mothers day.

Good info guys, I really appreciate the help and I am still learning a lot here. There is always more to learn...

Autotune made it run waaaay worse, to the point of leaning out off the map and stalling. No bueno.

odonnell

It's also possible that your wideband isn't conveying a realistic lamba signal due to ground interference (auto tune references commanded versus measured AFR). It's my understanding that VEMS has it built-in...is that the case here or are you using an existing controller via a signal input pin?

running_cold924

yes, using the integrated 4.2LSU style setup. I did the open air calibration to the sensor as well. Its now spot on. I still have my AEM wideband hooked up too so I can always monitor what comes through the exhaust.

Both are telling me the same signals however one is lambda, the other air/fuel. They both go rich and they both go lean together.

V2Rocket

you may know this (so this is a refresher ) but...
autotune sniffs the exhaust and adjusts the VE table to bring actual lambda inline with your lambda table target.

you said it runs well at like .7 lambda which is stupid rich. did you get it to run at that value by tweaking the lambda table or the VE table?

did you adjust your reqfuel yet? might want to start with a higher number (maybe 10 ms) and work your way down. larger injectors need smaller reqfuel ("on time") for a given amount of fuel required for idle/running.

not to say my tune is perfectly set up by any means but it runs darn well. if my 240cc or whatever NA injectors run great at 12ms and you were running at 5 or 6 that would logically match to a 480cc injector or so, right? since you have 380cc you need to UP the reqfuel time and "start over" with the VE table and auto tune.

SamGrant951

My req fuel was like 5.2 - 5.4 from memory, running 80# injectors.

running_cold924

Thanks guys, made some progress with it last night, it likes the timing bumped way up (around 18-20) at idle and I messed with reqfuel again. I think I just need more time as I only got to play with it for about 45 minutes yesterday...but stepping in the right direction finally.

Thanks for the help so far!

RostyToasty

Not for a 951 but I have a Porsche 944 s2 where did you buy the VEMSvems from online? also, did you need anything additional for the install? I want to break down and do it but I don't know where to start