Help with tune 383 LT1

[Terminal_Crazy]

Hi guys
Still stuggling with this 383 LT1 tune.

Tune was CLSD
Car drives fine once rolling, idle is good & stable until CL then it leans out. Of idle the car surges and runs lean upto around 20 mph. VE tables were set with Narrowband data.

I've tried playing with OL idle (PE) settings. The car idles much better when warm. It drives better from stopped but left clouds of smoke behind with it moderate throttle ( very rich).

I've just tried OLSD which again idled much better when warm but the wideband showed lean everywhere once rolling. I increased the VE tables by 7% across the board. Idle is rich and i'm still going lean off idle.
Feed back from here is that O2 sensors lie and widebands lie at low flow levels.

Where do i go from here... Use the wideband values to set VE tables or narrowband bacause i feel i'm going around in circles.


Weather is cold & wet and i'm getting miserable with the car as i can't drive it where it wants to be happy.


Poke me in the right direction please.

Thanks
Mitch

[steveo]

try not to obsess over AFR measurements

o2s do lie at low airflows, especially on engines with lots of overlap and stuff.

if it runs better 'rich', tune it 'rich'. if it runs better 'lean', tune it 'lean'.

if it has to run plug-fouling levels of rich to run properly, then you have a mechanical problem.

lets see your bin

[Terminal_Crazy]

The last run was great.
I've increased VE tables by about 10% just above idle & higher map.
The car would sit in first gear at about 3% throttle quite happy.
It would also take more pedal without launching violently.

Time to play with it now.

Thanks Steveo, update in a while.

Mitch

[Terminal_Crazy]

I'm now happy i seem to be getting somewhere. Car is getting much smoother and less aggressive in takeup. Also sounds much better.
I now have no knock counts (PCM has been changed though)
and the really big lean hole where ae should be has gone.

A couple of observations..

I'm getting a ERR 97 (4K vss fault) showing since flashing with EEHack 4.70.
First time out EEHack looked to be miles out compared with speedo...
Since gone back to EEHack 4.70 after 4.60, fault still shows speedo appears to agree with EEHack now.

If i turn the heater dial the a/c actuator display lights up on some settings.
When it does, the engine revs up and i've noticed the IAC increase upto 10 steps after which it settles down again.
Switching the a/c off drops the IAC and the rpm's drop again until it settles down.
IAC adder A/C pressure table is zeroed out.


THUMBS UP

Thanks
Mitch

[steveo]

between 4.6 and 4.7 eehack nothing has been added that would touch your bin or your speedo. must be coincidence.

other people have told me that their iac vs ac jacks up. never figured out why. i always deleted ac

[johnny_b]

My 383 does the samething. runs great in OL and I can always tell when it goes to CL cause the idle quality goes to crap. I know for sure its CL causing this because in EEhack if i force open loop and override aft to around 14.1-14.3 it runs great. Kur4o has a patch for $EE that allows OL idle. it works by going into OL whenever it sees BLM cell 16 (idle, 0% tps). you may give it a try. he posted it in the "two major $EE questions" thread.

[Terminal_Crazy]

My 383 does the samething. runs great in OL and I can always tell when it goes to CL cause the idle quality goes to crap. I know for sure its CL causing this because in EEhack if i force open loop and override aft to around 14.1-14.3 it runs great. Kur4o has a patch for $EE that allows OL idle. it works by going into OL whenever it sees BLM cell 16 (idle, 0% tps). you may give it a try. he posted it in the "two major $EE questions" thread.

I tried the OL idle and it was a big improvement.
However the motor went really lean at minimal throttle settings, under decent load it ran OK.
OLSD drives miles better. so far, just needs dialing in.

[johnny_b]

I tried the OL idle and it was a big improvement. However the motor went really lean at minimal throttle settings, under decent load it ran OK. That's interesting. a result of it switching maybe? Or perhaps a transional fueling problem? Do you have any theories as to why this was happening? Did the same thing happen when you tried the PE idle trick? I wonder if steveo or kur4o could chime in and shed some light on why that was occurring.

[Terminal_Crazy]

That's interesting. a result of it switching maybe? Or perhaps a transional fueling problem? Do you have any theories as to why this was happening? Did the same thing happen when you tried the PE idle trick? I wonder if steveo or kur4o could chime in and shed some light on why that was occurring.

Idle was going lean when going into CL. I had hideous amount of knock all over whatever i did. Big lean spikes on throttle opening. Lean surge from standing start.

Since i bricked my PCM a week or so back, i swapped in another. All stupid knock has disappeared. Set to OL and car is so driveable. VE tables now need tuning with wideband rather than narrowband O2's.
The PE Idle worked ok. Car drove OK but puked black smoke out. I just went OL without spending too much time on it.

HTH

Mitch

[johnny_b]

Idle was going lean when going into CL. right, valve overlap from the cam corrupting the O2 sensor readings at idle. Sorry Mitch maybe you misunderstood me, what I'm curious about if i understood you correctly, is why the OL idle patch was causing you to go lean at low throttle settings?

[Terminal_Crazy]

right, valve overlap from the cam corrupting the O2 sensor readings at idle. Sorry Mitch maybe you misunderstood me, what I'm curious about if i understood you correctly, is why the OL idle patch was causing you to go lean at low throttle settings?

Idle i'd got running well.
CL the idle was lean and raggedy. Off idle was going very lean any time the throttle was opened upto 25-30mph.
I tried the CL PE idle which was vastly improved but was very rich as it was set up.
I've just gone OL SD instead and need to relog & reflow my VE Tables.

Mitch