Weird Values in B1602

[LastCall]

Working on a tune for a Trailblazer SS, and a little stumped. It is an 06 which usually runs an E40 PCM, but it is running an E67. The operating system is 12618164, which I could not find a stock cal for. I looked at an 07 E67 file, and values in B1602 are significantly different.

The issue is I'm trying to nail down a hot start issue, where the truck starts, and dies shortly after. Give it some pedal, and it will idle fine after a few seconds. Driving around is fine. It's just start up.

I've attached the two tunes, I could not paste then in this message.

[LastCall]

So looking (using search function - haha), it looks like the factor is multiplied bu the min idle airflow. Does that sound right? Not sure why airflow would be cut in half in any circumstance.

What am I missing?

[ScarabEpic22]

That OS is for an 08 TBSS, I know as it's the OS my truck has and not an 06.

I've seen some swaps with the entire engine harness has been swapped out when the motor was replaced for a 58x/4x setup vs 24x/1x.

Check out this thread and see if one of the stock files would work: 08 TBSS OS (https://forum.efilive.com/showthread.php?7937-08-TBSS-E67-fan-control&highlight=12618164) Per the file in that thread and the one you attached here, they're identical (per EFILive).

I'm a tad confused, do you need a stock 07 file?

[LastCall]

That OS is for an 08 TBSS, I know as it's the OS my truck has and not an 06.

I've seen some swaps with the entire engine harness has been swapped out when the motor was replaced for a 58x/4x setup vs 24x/1x.

Check out this thread and see if one of the stock files would work: 08 TBSS OS (https://forum.efilive.com/showthread.php?7937-08-TBSS-E67-fan-control&highlight=12618164) Per the file in that thread and the one you attached here, they're identical (per EFILive).

I'm a tad confused, do you need a stock 07 file?

Thanks for the response.

I have the 08 file, and compared it to what I have. My question was more about table B1602, and it's affect on engine coolant temp and airflow. Have a hot start issue where it starts and stumbles before idling normal. So I went through the tables and was trying to understand the role of B1602 in the 07 and 08 OS cals. The values in the 08 are very low, so I'm thinking that minimum idle airflow might be getting cut down significantly (in half) .25-5 in the 2008 vs .88-1.00 in the 2007.

Do you know how airflow is measured at start up? Is it minimum idle airflow plus cranking multiplied by B1602? And does the airflow calcs come from MAF or VVE?

Sorry for the questions, just trying to understand how the air is measured/calculated at start up.

[LastCall]

Anybody else?

[swingtan]

Hi guys, a couple of questions here....


What was the reason the the tuning? IE. have there been any mechanical mods?
Was this issue occurring prior to tuning or only after?


As you probably know, B1602 only comes into play once the ECM switches from cranking mode to idle mode. I've seen a few tunes that have the table set as in the )* tune posted, as well as others that have significantly higher values. For example, I'm currently running values of 1.8 in the colder ECT cells in my tune. I'd be using the stock values for the OS in use as a starting point, adjuxting by increments of maybe 10%

Airflow for cranking is managed in B1832, and a couple of other tables (missing in the 08 tun file) B1833 and B1834, set when the ECM switches from cranking airflow to idle airflow.

If the Engine starts and idles OK when cold, then I'd take a guess that the basic airflow tables should be OK. I must say though, that the cranking air flows in the 08 tune look pretty high though. If the min idle air flow is set to 7.5gm/S, I'd have expected the hot cranking air flow to only be a couple of gm/S over that (other mods to the engine may change this).

Do you have a log of the issue that shows IBPW as well as spark, MAP, RPM, ETCTP/TPS ?


Simon.

[LastCall]

Hi guys, a couple of questions here....


What was the reason the the tuning? IE. have there been any mechanical mods?
Was this issue occurring prior to tuning or only after?


As you probably know, B1602 only comes into play once the ECM switches from cranking mode to idle mode. I've seen a few tunes that have the table set as in the )* tune posted, as well as others that have significantly higher values. For example, I'm currently running values of 1.8 in the colder ECT cells in my tune. I'd be using the stock values for the OS in use as a starting point, adjuxting by increments of maybe 10%

Airflow for cranking is managed in B1832, and a couple of other tables (missing in the 08 tun file) B1833 and B1834, set when the ECM switches from cranking airflow to idle airflow.

If the Engine starts and idles OK when cold, then I'd take a guess that the basic airflow tables should be OK. I must say though, that the cranking air flows in the 08 tune look pretty high though. If the min idle air flow is set to 7.5gm/S, I'd have expected the hot cranking air flow to only be a couple of gm/S over that (other mods to the engine may change this).

Do you have a log of the issue that shows IBPW as well as spark, MAP, RPM, ETCTP/TPS ?


Simon.

Thanks for the response Simon.

Answers to your first two questions;


The reason for the tuning was because the LS3 engine blew up. A fresh LS2 was swapped in with a cam 229/231 on a 114 LSA + 3 ground in.
This issue started happening with the cammed LS2

As far as B1602 goes, I left the factory values there. I was confused on when the factor was applied (cranking vs idle), so thanks for the clarification. Do you know what it get's multiplied with?

For B1832, I added air (1 gram at a time) all the way up to 17 without a change in starting behavior, up to 3 seconds of run time. I also played with the cranking fuel and timing while cranking. See attached tune.

I have a few logs, but don't have Injpw PIDs. See attached.

Thank you for your time.

[swingtan]

Oh..... LS3 to LS2.... Did you keep the same TB or use the one that was on the LS2? First thing I'd do is make sure you are using the same TB as was in the vehicle before. There is a difference between the Gold and Silver butterfly TB's at least there was in Australia).

Aslo, you should be logging ETC-TP for these cars, as it will report the correct TP%