RZRSEDGE

iTrader: (21)

Doing some tuning on my Z since the new cam went in. Got the RTT option from HP tuners yesterday, still working on getting used to how to use it. Anyways, while logging, I've noticed that my idle spark seems to be everywhere. Something else that's strange is while working with the idle spark, the car seems to be the smoothest and have the most manifold pressure @ 15* timing. That seems extremely low to me. Car has ported heads, custom Pat G. specd 232/238 on 111 cam, ported 92/92, stall, and full bolt-ons minus a EWP. I think that I may find the answer in the idle overspeed/underspeed corrections. Am I going in the correct direction? Here's a scan from working on the RAF. A rough in of the VE has already been done. Any help is greatly appreciated!

DaveX

Sounds like the overspeed/underspeed corrections to me. I toned mine down a bit.

jimmyblue

iTrader: (11)

Yes, the idle spark corrections are probably "busier" trying to
stabilize RPM with the new cam.

The idle control loop has a lot of "stuff" going on. If you make
the idle conditions crappy (low advance, rich, etc.) you may
get to a smooth idle because only the IAC has much authority
and it's slow. But give it "proper" spark and fuel, and now
things like VE table values, in places you don't think you'd
ever see, start to matter; MAP-slope of the table leads to
fuel surge, MAP surge leads to spark bounce and it's all a
bowl of spaghetti.

When trying to tune idle airflow and fueling, probably want
the adaptive spark disabled. This will keep it from "helping"
and you'll have more clarity on the other dimensions. Of
course it may more clearly die at idle, but that's just your
feedback taken to the extreme.

RZRSEDGE

iTrader: (21)

Thanks for the advice all! I think I'll disable it and retune the RAF and VE. It drives pretty well, just know that it can be better. It's not exactly as smooth as the MS3 it replaced; but I had lots more tuning time with that cam. Thanks again!

RZRSEDGE

iTrader: (21)

Bringing this back up. Okay, disabled the over/underspeed and did a scan for the idle airflow. Died a couple of times at the first of the scan. Wasn't much different then the values I had already; but some. What do I need to do now? Want to get my spark stabalized. The car is still in SD mode for VE tuning per Bill's instructions in the HP tuners help guide. Should I ensure that the VE table is correct with the over/under tables still zeroed out, then try to adjust idle spark before enabling the tables again? Kinda lost here? With the tables disabled, I get a lot of surge and makes it hard to find the timing that is gonna give the most MAP reading. Also, what do I need to work with to get the car to quickly come back to idle after giving it the gas instead of it searching for a second or two? I think when I get the spark figured out that will help this greatly. All help is greatly appreciated!

jimmyblue

iTrader: (11)

Begin with leaning out the 400RPM column of the VE
table (do you use the real time tuning OS? Handy).
You can't trust narrowband or wideband readings
down low with a big cam, go by what makes MAP
head lower and the motor sound better / swing
less in RPM. If you intend to go back to closed loop
then first get it right, record the wideband AFR that
"works" and then you'd mess the NBO2 switchpoints
around until you're seeing that AFR again when the
thing has trimmed in (probably to a much lower
NBO2 threshold). 800RPM may want a little tweak
but the real trouble is in the RPM where you can't
spend time or get data - the below-desired-idle
RPM range, where you step on every surge's low
excursion.

I'd lock the spark advance and IAC, and play with
AFR as the first step, just to scope out what the
motor really likes. When you find the AFR for min
MAP, then lock the AFR and dial the IAC down,
re-trim the spark, etc. until you have gotten to
a minimum idle RPM that the motor can hold clean.
Like if you can "Cadillac it down" to 500-600RPM,
it ought to have no problem being happy at 800.
But if it's lurching around at 800, dropping to 700
for whatever reason might make it fall over.

As you tamp down the RPM you should gain a
decent picture of what the spark and fueling ought
to be; then you can try working the VE table to
get the same fueling (with trims suppressed) and
put the spark roughly right (without active idle
spark correction) and get the airflow targets to
sit a little above where it really is going to idle.
Set the spark to less than best, so that the
adaptive spark aids RPM strongly (not does
nothing, that's a recipe for instability as is any
feature like the stock tables where it pushes
harder but then gives up when error is large;
that's a ditch waiting for you to drive into it,
data-wise). Pimp idle gots to have smooth
data.

Strip away all the "help" and adjust the "big
three" bare of all that foolery. Then when it's
old school solid you can fancy it back up.

RZRSEDGE

iTrader: (21)

Okay, will do! Should I lock the spark to say 25*, the IAC steps to say 55 and push around the AFR until I get min MAP. Keep the AFR locked through the VCM controls, now how would I change my desired IAC steps after pushing it around in the VCM controls? When I push the spark around I'm looking for the maximum MAP reading, correct? What do I adjust to get the airflow targets slightly above where they need to be, would I just add a small amount over desired to my idle airflow tables? Sorry for all the questions, I am trying to learn all that I can about tuning. It seems the idle seems to be the hardest part for me right now. Thanks for the help!

RZRSEDGE

iTrader: (21)

Bump for confirmation!

jimmyblue

iTrader: (11)

You don't work with IAC steps directly, in the tune;
that comes from the base running airflow for the
different states (in gear or not, A/C or not, etc.).
Once you get to where you understand the best
spark position and happy idle fueling then you'd
look at what is the airflow for the target RPM, aim
maybe 10% higher than that for RAF table targets
(so the PCM's "initial guess" favors staying alive).

Main thing is, to get the fuel (airflow accuracy)
and spark cleaned up so that you get stability at
any load-point and so the airflow you aim at, is
one that is good enough for that mixture, spark
and motor load.

Remember to use maybe 5-10 degrees less than
"best" (min MAP) spark advance, in the idle advance
tables, so that the adaptive spark (when enabled)
has some upside authority.

RZRSEDGE

iTrader: (21)

Many thanks! I'll probably have more questions in the near future, so please be patient with me!

RZRSEDGE

iTrader: (21)

Okay. Got a chance to work with this some the other day. Locked my spark in @ 25. Locked my IAC steps at 85, car idled high; but this was the only way I could get it some what stabalized. Pushed the fueling around and seemed to like 15.1 the best. The MAP reading was fluctuating with the idle, so I watched for the min MAP. Locked desired at 15.1, wideband showed it to be very close, and turned to spark. I pushed spark up and up. Got lower MAP readings all the way to 38*. Idle was high; but smooth. Almost no MAP fluctuation. Tried it up to 40* but it made no difference. Is 38* too high? I set my P/N spark @ 30* and re enabled my over/under tables. Should I increase my under speed table to 8* to make up the difference?

Viper

iTrader: (6)

Subscribing

RZRSEDGE

iTrader: (21)

Bringing this up.

ringram

Idle spark shouldnt be that high, you want it midway from mbt to retarded so that the ECU can vary it to maintain idle with spark only. If it has to move the IAC then thats slower and not as good. What cam do you have? Try timing around 19* or so at idle

RZRSEDGE

iTrader: (21)

Cam is custom ground 232/238, XFI lobes on a 111. Ported heads, Fast and all the other goodies. Stock timing was at 18*. Idle wasn't bad; but when you hit the gas and let off, it stumbled and rpms swung for a while. The higher I push timing the less MAP I got, which is what I was looking for.