WS6FirebirdTA00

iTrader: (33)

OK I thought you still had the 224, with a cam larger like that you will need to allow for a hair more idle airflow through a hole or a slitghtly cracked tb blade (as long as the TPS VOLTAGE is fixed by rotating the TPS sensor to lower it to around 0.55 V). Doesnt need much but just a little bit to get the IAC steps down.

xaon

iTrader: (12)

I'm with him. You could probably get away with adjusting the idle set-screw some and getting the extra airflow you need. (You don't need a whole lot, your setup is pretty close if all it is doing is surging some)

Work in small increments, 1/8 - 1/4 turn at a time, and reset the TPS after each adjustment.

TPS Reset procedure:
1. Unplug TPS sensor
2. Turn Key to Run (do not start car) and let sit on for 1 minute. Turn Key off.
3. Plug TPS sensor back in

That should reset the Absolute Throttle position back down to 0%, since you shouldn't have to adjust TOO much, you should be fine with this method.

OR alternatively, you can drill the hole in the throttle body larger, start with a drill bit JUST bigger (try to go in 1/64" increments) that the hole that is already in the NW throttle body.

BADFNZ

iTrader: (19)

I've done the TB screw and TPS reset about 10 times in the past week. It definitely made it better but still not as good as it should be.

So I'm guessing SD won't help idle issues in any way? Is it easier to tune idle in either form?

xaon

iTrader: (12)

Switching over to SD wouldn't really help for most idle issues... especially not on a cam that small... It still sounds to me like the car needs more airflow, if it were getting too much it would hang the idle and not surge anymore. I'd keep going up some.

Otherwise, i'm not sure what the deal is... that setup should not be that hard to tune.

jimmyblue

iTrader: (11)

There are things that compound the idle airflow problem,
on cold starts, such as the high idle MAP pushing you
into deep enrichment in the open loop fuel/air table
(aka EQ Ratio vs MAP vs ECT). Rich means sluggish.
Any of the usual VE table low-end error compounds
this and both of them further depress MAP. You can
lean out the cold cells anywhere below your PE enable
threshold MAP without much problem, and this may
relieve the surging some.

The idle airflow table needs to be reworked in the
temperature dimension, even though you most likely
have little data to go on. If you can log a cold idle
startup from key-on to closed loop enable temp,
and catch the real airflow needed (as the PCM sees
it - dynamic airflow PID) then you can get a decent
idea of the temperature-based needs of the motor.
You will have to extrapolate as best you can, for
temps below what you have seen. However GM
seemed content to just flatline it below freezing.

Note that if you go and change the VE table chasing
the fueling-based component of surging (I see this
as sluggishness of response, destabilizing the RPM
control loop, which is one thing that more spark in
the idle spark advance table helps, this table should
stay in sync with the main table but sometimes it
goes untouched) you will change the calculated airflow
and then have to change the idle airflow table some
to get back to the -real- airflow that works for RPM.

WS6FirebirdTA00

iTrader: (33)

Only problem with moving the throttle is the TPS can get too high to where the computer will make calculations as non idle. What I do is drill larger holes for the bolts on the sensor and rotate it to get .53-.57 volts and then do a reset for the tps.

xaon

iTrader: (12)

His setup shouldn't fall far enough outside of the voltage limits of the TPS. Mine sits middle .6's at idle with no issues, I didn't have issues with mine until it was in the .9+ range, which even at that area was not an issue at idle, but an issue with going WOT as I began to sit very near to the 5v limit. I ended up backing mine off and drilling a 7/32" hole... My setup is quite different though and requires lots of air. (FAST 90/NW 90, 7/32" hole in TB blade, blade still cracked open some more, and my Desired Airflow counts are at either 16 or 18)

soundengineer

iTrader: (16)

Its a losing battel trying to tell people about the TB hole...
most dont understand all of teh other things in tehtune taht you cant see that it does mess with...
there is a very good reason for drilling a hole....
just liek there is a reason for an idle bleeder on a carbed car..
the idle bleeder for our TB is a DRILL HOLE..not the bump stop used to keep the tb blade from getting stuck at teh bottom of its range

WS6FirebirdTA00

iTrader: (33)

The only reason I dont drill holes in the blade is

-easier to adjust on for small airflow amounts
-if you want to sell your setup it is easier to sell

Both will do the same thing in the end if done correctly.

TheBlurLS1

iTrader: (8)

My car ran perfectly, perfect start, no surging, the I slapped on the FAST/NW 90. Cold start surging was horrible, I had to keep my foot on the gas to keep the car running. The NW 90 hole is TINY, I drilled it out to 13/64th and it went right back to the way it was before.

xaon

iTrader: (12)

13/64" is the hole I have always used on pretty much every setup i've worked on to idle properly. Even before when there was no tuning software available. Everything from small mild 216 duration cams, up to the big monster low 24x duration cams.

It wasn't until I went to a 408 with a 248/254 cam that I needed to go bigger... with my LS6 intake/ported Throttle body I had TWO 13/64" holes drilled in the blade to keep the airflow up enough. When I switched to a FAST 90, I played and played with the set screw, finally said F'it and drilled out the hole to a 7/32" (I would've done 13/64", but I was impatient and couldn't find it. )and then backed off the set screw until it idled properly. I still get a very minor amount of surge on startup with the A/C on, (idles up, drops down to maybe 800, up to 1200, and then settles back at 1000 where it should be)... I'm pretty confident that bumping the desired airflow table up just another hair will fix it (but then again, the car doesn't die on me, so it's not that big of a deal)

WS6FirebirdTA00

iTrader: (33)

The IAC opening is also different than stock so it needs some tweaking. That is all I had to do to my tune after the swap for idle.

BADFNZ

iTrader: (19)

Well from what you guys are saying, going SD won't necessarily help my idle issues so I should probably just stick with the MAF and just pick up a cheap 85mm one.

Can anyone tell me the advantages of SD over a MAF? jk

Country Boy

iTrader: (24)

I have to disagree with needing a hole in the throttle blade. I was running the G5X3 and some good heads and have never had a hole in the throttle blade (altered TB) and it idled just fine. No surging, no stalling, etc...

soundengineer

iTrader: (16)

its not about the IAC opening..its about the actual IAC pintle ...
so you dont need to change the IAC effective area table unless you uput a different IAC motor in the TB

people move their Effective area table vs tehir actual dynamic airflow..and thats not a correct amount...

soundengineer

iTrader: (16)

there are many factors that determine all of that...
teh simplest thing to clear it all up is to drill a hole...
you can tweak a lot of other things and it will still idle just fine...
but the thing most cars are looking for is a litlle more timing and a little more idle air...
typically if you can get the IAC counts to be "not maxed out" then it will idle fine with some major tweaks to the base Running airflow table

but the majority of people who live in a climate that gets pretty dam cold in the winter will need more air than teh IAC motor will allow and need it to come in quicker than the IAC motor can adjust at the end of its movement range

soundengineer

iTrader: (16)

actually SD does help some as sometimes Idle issue are caused by MAF reversion issues(meaning the cam breathes too much back and forth at idle)

DAPSUPRSLO

iTrader: (14)

So the TPS on an ETC vehicle is essentially the same thing as IAC counts on a cable vehicle correct? You're saying you need to place a hole in the ETC vehicles blade to get the TPS to that 3-4% range?

soundengineer

iTrader: (16)

maximum is around 7% ish before it starts causing other issues

and most of them stock are around 3-4% ish..

some are a little higher..some a little lower..completely depends on teh vehicle in question

oztrack

If people dont populate the Power enrichment IAT correction table when doing a SD tune they will end up quite lean in hot weather and too rich in cold weather. But trims will take care of things the rest of the time.

However there is a big shift in fuel needs from hot to cold weather. Get your car tuned in summer not winter - because a winter tune that is lean and mean will be TOO lean for hot weather UNLESS as i said above the right tables are populated - make sure you know as a customer this has been done or you could damage the engine - take it back if you ever hear any pinging in summer