$50 Bounty!! LNF Cat Warmup Delete

[Jaizero]

Guys/gals,

I've been trying to get my car to start up properly in very cold weather with cat warmup delete. I have been thusfar unsuccessful. Attached is my current tune with cat warmup enabled with cams in the stock configuration. I will pay the first person to get my car to start and idle properly with the cat warmup deleted $50.00 via Paypal or Venmo.

The issues I'm having are when the car starts up and is very cold, instead of idling where I've set it, it will bog out and stall. Sometimes, it will bog out then correct itself several times before it settles and idles ok. I have not been able to correct this with any adjustments to Optimum Spark, Optimum Torque, etc.

The first attachment is with cat warmup enabled.
The second attachment is my attempt and disabling it.


2009 Cobalt SS Stock File Modified Cat Warmup Delete OS increase.hpt
2009 Cobalt SS Stock File Modified Cat Warmup Delete OS increase Idle Spark.hpt

Thanks for looking!

[TurboCobalt]

Haha, I?ve had the same problem on my cobalt and solved it. I live in Michigan and a few days ago I had a perfect -4F cold start with cat light off turned off.

A few things I remember doing.
1)Cam changes: Park all the idle cat light off cam tables.
2) raise the idle rpm at coolant lower temps.
3) spark and optimum spark tables can be used to modified spark to have a better spark advance during the cold start.
4) this was by far most important part and kind of the least intuitive. Your mass air flow table, the one where the axis is Hz and output is airflow this has to be perfect. My cold start got as high as 3200hz ( air flow) if I remember correctly, so make sure you tune your maf sensor to be spot on below 4kHz. I have a pretty stock cobalt with stock airbox and kn filter. If your struggling to tune the maf table you can just smoothly, gradually increase those values in low frequency and waiting for the next cold start to see if it?s better. Preferably just tune the maf with recorded data.

If you need more help about any of the points or how I did it let me know.

[Jaizero]

I?ve tried about everything, including parked cams etc. I haven?t retuned my MAF vs freq table for a long time, I?ve just been using the MAF base for corrections. I?ll dial in the MAF vs freq table again and see if things improve. Thanks for the tip!

[TurboCobalt]

Post a log file if you?d like I?ll take a look at it to see if it?s something else. But I was struggling with the same problem for a while until someone on here told me to fine tune the maf and it made a world of difference. Unfortunately it had to be just about perfect, and I looked at your maf tune already and it looked a little choppy at one point to me .

[cobaltssoverbooster]

try an old trick i did a few years back and see how you like it.

disable evap solenoid and log stft against rpm and load but dont define any axis labels just set the axis parameters. this should make a histogram with only one active box that reads at any rpm and load value.
set the maf base to 1 to disable the table and leave the factory maf sensor curve data in the tune file.

now let that bad boy sit at idle (at operating temp) for a while while you record a nice 8-10 minute log. this log doesnt need 30 minutes of driving because its only targeting the idle zone cells.
every 2 minutes your going to change the idle load by using driver comfort features. first 2 minutes everything is turned off, then turn on the radio and the heater and defrosters (no ac because thats a direct crank load, the heater system is a electrical alternator load.) , then switch over to ac in defrost mode with radio on, and and fog lights if you have them. the changes in vehicle system loads changes the crank load at idle allowing it to wander around the histogram collecting a global average of idle behavior.

now apply the average the histogram reports back to the injector constant table. std multiply by percent "half" technique. do this however many times until you are happy with the reported idle trim error.

now from there tune your maf.

the idea of this technique is to bias the global injector data to favor the idle area of the engine. anything above idle is very easy to tune and falls right into place with a little bit of trim massaging so loosing precision there really doesn't hurt us since we are tuning by a wideband given to us by gm as a stock component.
it is possible to calibrate the injector constant on a more global scale by increasing the log time and performing a drive instead of sitting at idle. i found benefits and trade-offs to both ways. maybe it helps you.

[Jaizero]

Another great idea! I?ve spent so much time tinkering with everything else, it might be a good idea to step back and start with the simplest things. I will definitely give it a try. It?s like -7F this morning so I?ll probably have to take it for a drive to get to operating temp, idling won?t get me there lol..

[TurboCobalt]

i have higher idle rpms than you: at -30C=1450, at -15c=1350, at 0c=1150 at 30C=900. i think your cold temp idles are too low.
i noticed you have different injector constant than me, do you have opel injectors or something? I just used the MAF table to tune and left injector stock. alternative of course is to scale injector like CSSOB recommended.

personally i wouldn't tune with "maf correction base" table like you did, values are too high and way too "jagged" you have zig zags in that table, set it to one, and get your "Airflow vs Frequency" more accurate. then only minor tqeaks in "maf correction base".

looking through your tune torque >> general >> ETC Limit >> Tq Mgt Inj Disable, from the way you have it tuned doesn't seem like you understand how that works, i would recommended returning it back to stock.

in general you use a different way to tune your torque control / boost control compared to me, i guess that's a matter of opinion of what you like so i guess it doesn't matter. do you have a boost spike issue at med range RPM?

From your spark tables, are you running some ethanol mix? e47? if so, that will make it a bit harder to cold start. If you are not running an ethanol blend, your spark at high load high rpm is WAY too high.

EDIT: also, you can tune it right and still use overboost/underboost diagnostics; you dont have to turn them off, then if a mechanical failure does happen the engine controller can protect the engine, AND help you trouble shoot your car cause you had a DTC now.

[Jaizero]

Yup I?m running e47. Some of the settings were copy/pasted from a e47 tune I paid for hence some of the weird things you are seeing. I wanted to start from scratch and do the tune myself only copying the necessary tables to get me started. I?ve read everything you guys have posted and I?m grateful for the advice. I?ve started working on the MAF and will post a log sometime this afternoon.

[Jaizero]

It?s an fbo car with a Z54 turbo FYI. As far as boost spikes go, ever since I went from the Treadstone CAI to the K&N sri the turbo wants to spool at low rpm/low load lol. I?ve been trying to calm it down and have been moderately successful. It wants to spool in second gear with light throttle input.

[2000Firehawk]

Look at my attached file to see if there's anything that may help you with your cold start issue...

It is -2 in Pittsburgh right now, & my LNF started just fine, even at my low idle setting of 1,000rpm...
I'm running E47 also...

I used to have problems with cold starts, but my problems went away when I replaced my battery with a new AC Delco unit...
My old AC Delco battery had a 'cell' going bad...
Maybe a 'fresh' new battery will make your problems go away....

[Jaizero]

Look at my attached file to see if there's anything that may help you with your cold start issue...

It is -2 in Pittsburgh right now, & my LNF started just fine, even at my low idle setting of 1,000rpm...
I'm running E47 also...

I used to have problems with cold starts, but my problems went away when I replaced my battery with a new AC Delco unit...
My old AC Delco battery had a 'cell' going bad...
Maybe a 'fresh' new battery will make your problems go away....

Thanks a lot, I'll give it a look over! It's 3 degrees here in Wisconsin this morning and the car started just fine. I did go through and recalibrate the injector constant/MAF as suggested above. Not sure if that helped any because the car will start just fine for a few mornings, then fall on it's face on others. We'll see how it acts over the next few days. Again, thank you guys for your insight and suggestions!