Hot starts are killing me with the 2300.

[99-LS1-SS]

As most of you know I just got a 2300 and it is kicking my ass. Once it's running it's fine. It runs at the commanded AFR at WOT and had great driving manors....just like stock. My trouble starts when I turn the car off after driving it. It doesn't want to start back up. The only way I can get it to start is to floor it and try to start it and then the next time I turn the key it will work. That's embarrassing to say the least.

ANY tuners that have experience in overcoming this issue please give me some assistance. I've tried a bunch of different tunes and combinations but nothing seems to work.

[Patrick G]

Look at the cranking spark. Most of the time it's like 2-10 degrees, but once it gets hot it goes to -10 degrees. Set it to 2 degrees and see if it gets any better.

[99-LS1-SS]

I saw that but I thought it was like that for a reason. In the main cranking areas at the higher temps the timing is set to -10. What is the logic behind that?

I finally made progress last night. Here is what was happening.


Since I have a custom fuel system I went and changed the Desired Pressure under the Fuel System tab. I had changed all of the values to 58 psi. Well like an idiot I didn't change any of the other tables. My car was putting a steady 58 psi through the fuel system but my cranking pressure was still set at ~11.5 psi (factory setting). I changed those values to match the constant 58 psi line pressure and put all the other tune values back to stock except spark tables and MAF table. I loaded the tune and unhooked the battery for 10 minutes. Got in the car waited for the pumps to prime and it started up! I let it idle for 10 minutes to get the temps up in the engine and cut it off for a couple of minutes. Got in and turned the key and it started up again!!!! Then I got brave and drove it for 20 minutes and cut it off. Waited and what do you know....it started again.

I have to fine tune the startup airflow just a little to help start a little quicker.

Someone suggested that I adjust the Open Loop gas a little to help it start a little quicker. It turns over about 3 or 4 times before it fires. It has never started fast even stock. What do you think about that suggestion Patrick?

Here is my current tune with the Open Loop and the cranking timing adjusted. Does anything look out of line?

[tbully]

Interesting problem. I'm watching for updates as I plan to supercharge in the future as well.

Agree in the slow starting....mine does it (stock) as well.

(GXP 6M)

[Patrick G]

I would be very careful with the knock sensors. Right now, they are desensitized and the knock limits are cut back. While you're tuning, you need to set them to stock. You should make your IAT tables more aggressive at lower temps. This will allow you to run a little more timing in your main spark table, but let the IAT table start pulling timing once it gets over a certain temp (like 113f). Once IATs get over 140f, you'll want to get pretty aggressive with your timing retard. Probably don't need to have your PE EQ ratio at 1.309 until the rpm where you get into some boost. I would keep it around 1.18 from 0-1000 rpm, then start ramping it up after that. Don't need it overly rich at low rpm with little to no boost, especially with a stick shift.

[99-LS1-SS]

Thanks for the info about the knock sensors Patrick. I had turned them down with my previous tune before I got the supercharger. Thanks for the other tips as well. I'm off to make some changes.

[G8-4-Speed]

bump your startup airflow. Use that SS file I sent.....