LS1PoweredZ28

iTrader: (2)

Background:
The car is currently running in open loop as I work on my SD tune. I've been having 2 major problems (which may or may not be related) during cold start/driving.

Problem #1:
Attachment 1 is a screenshot of a cold start after the car sat overnight. As you can see, I'm getting crazy amounts of knock during all conditions (idle and driveing), I can't figure out why this is happening. During my last log, I turned off the car and back on at a traffic light (see highlighted area in attachment 2) and the problem goes away. Anyone have any clue?

Problem #2:
Once again when the car is cold, I pull out of my apartment and stop at the traffic light by my place (about 3-4 minutes after start up). When the light changes and I go to pull out on to the main street, the car will go really lean on every shift and fall flat on its face (runs really rough and feels like it has about 10hp). Attachment 3 shows it in action.

With the second problem, after about 10 minutes everything smooths out and the car runs great. Anyone have any ideas about what would cause this?

Sorry for the long read,
Kevin

NYSS Guy

iTrader: (1)

I'm pretty new to tuning, but I'm in the middle of my own open loop sd tune. THe one thing I noticed is your narrowband o2 sensors are still reporting information. From what I understand, they shouldn't be. So, maybe the car is getting information that is causing it to run odd. Hope that helps somewhat.

LS1PoweredZ28

iTrader: (2)

One narrowband is still plugged in, and the the other signal is the WB simulated signal. My closeloop enable temp is set to 258ish and the Fuel System Status says that the car is running in open loop, so even though they are giving a signal from what I understand the computer should be ignoring them.

Kevin

white2001s10

iTrader: (4)

Unhook the O2 from the PCM.
My guess is that it's just simply lean.

When you turn the car off and then re-start it goes into start-up enrichment which is on top of warm-up enrichment... more fuel, and you say the problem goes away.

I think you just need to reshape the coolant correction fueling a little.
On a dead-cold start some cars want 12.0:1 AFR or richer. Watch your wideband.

LS1PoweredZ28

iTrader: (2)

I'll try unhooking the O2s. My open loop fuel table is pretty rich at low ECTs, but I'll definetly try richening it up some more to see if that helps.

Thanks guys keep the help coming,
Kevin

RedHardSupra

iTrader: (1)

if you only got idle problems that are ECT dependent, that means it's the RAF table. tune it, and idle and general drivability will get much better.

LS1PoweredZ28

iTrader: (2)

I will repeat the RAF spreadsheet a few more times, I just need a cold morning to get a good ECT range.

Kevin