Stock L92 Powered Bracket Car

BLUF: someone vector check me

Details: Stock L92 (07) Non DoD
Amazon Headers
Stock intake from MAF to TB
TH350Trans
No VSS

Tune and Log: Attachment 160955Attachment 160956

Overview: Building a bracket car for my wife. 86 Grand Am converted to RWD. Just want it to run great, get safe yet decent throttle response.

Ive done a pile of research into Gen4 tuning. Im trying to isolate whether or not I have a bad 02, or an issue with B2 as im getting misfires on B2. But, the main reason im posting is the idle hangs for quite awhile after a throttle blip to return to steady state (somewhat, I can see its +/- timing pretty aggressively to maintain).

Any insight is greatly appreciated. I want to learn, but I also dont want to make the car dangerous (ie. surging throttle in the staging lanes wouldnt be ideal for a new driver).

Cheers,

-Brennan

Looked through the log file and found there is a DTC present for 02 B2S1 heater circuit open. So I do have a dead sensor on B2 - likely causing the misfires on B2. Ill get new sensors and post back. Would it be worth trying to tune the MAF at Idle with a wideband 02. I have an Innovate LM-2 I have to hookup, didnt want to kill the sensor if the motor had some fueling issues. I should note the NB02s are at the collector for the headers and theres 3 feet of pipe before the dump out.

The tune file looks almost completely stock. The no vss could be causing some of those issues with the idle hang.

2XLS1,

The tune file is almost stock, Im hoping to be able to work through the idle tables to help with idle hang. I dug up an old file from 2 years ago I logged the truck before I pulled the engine and the 02s were working fine then. Likely moisture killed them. I will hook up the wideband and try and see if/how far off the MAF tables are following Goat Rope Garages guidance on youtube after replacing the O2s. Im more or less gonna use the forum to document changes, and bounce things off people to make sure im not going in the complete wrong direction. I cant be the only running a auto truck ETC/Pedal without VSS:pray: Only 20 days to the first weekend of racing.

Update - Installed 2 new NB02s - logging much better - LTFTs are still off. Hooked LM-2 wideband up after 4 hours of repairing it (bought at an amazon return store for $25) Got it running, calibrated sensor - WB showed it was lean at 1.36 at idle with no throttle input. Applied some throttle and instantly went to 1.00, went back to idle at 1.36. I'm assuming dynamic airflow needs some work. Working on integrating the LM-2 to HPtuners with no initial success - ill keep at it.

Well got the LM-2 to work! followed tips here on the forum - set the comport for the serial adapter in to COM1. works like a charm.

Heres a log file with the WB02Attachment 160988

The correct way to go now would be EQ error tuning on the MAF at idle correct? would I do it including dynamic airflow or disable?

Cheers

Brennan

Use the fuel trims unless you plan on running in Open Loop all the time, and even then id probably trust the O2s over the WB. Yeah youll have to dial in the MAF. Seems weird if you are running the stock intake assemble, the MAF is that far off? Might have to touch up on the VE for the headers.

It is somewhat stock. I cut the expansion areas out as I had to turn the intake down to clear the hood. Then infront of the MAF is a short piece of 4? aluminum pipe. I do agree I am not sure why it would create a drastic LTFT change. The exhaust I can see it breathing a little better.

I am just trying to get the LTFTs to stabilize. I managed to get the Math parameters set to log against the WB. Was showing 30% eq error. Made a change in the MAF table - no change on the WB but the NBs were showing rich rich rich.

Got a little tired figured I?ll work it out tomorrow, leaned over the bay and looked at an empty O2 bung in the crossover pipe (forgot to plug it). Wonder if that would cause the WB to show lean?🤣

Any change to the intake plumbing will change the maf calibration.

Why use a MAF on something like this at all? Need to pass emissions inspection? On a dedicated bracket car?

Blindsquirrel,

It?s my understanding running a MAF is the easiest way to tune a N/A stock motor. Would SD be easier/better? I?ll do some research on SD

Your file doesn't have a 2-bar SD option. But 2007 Corvette does, which should use the same ECM service number. But but, you don't have a way to change to that OS/VIN if your only tool is HPTuners, a change like that requires GM SPS/Techline subscription & compatible J2534 tool. But but but, making that change would give you a proper non-auto-trans OS that's able to read a VSS and isn't constantly wondering what happened to its friend the TCM. Idle will work better, and all kinds of other things too. You might have to change the pedal/APP sensor, I don't know the full story on what interchanges for each OS/year. The time for dealing with problems like this is before you even get started.

Quote:

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Originally Posted by blindsquirrel

Your file doesn't have a 2-bar SD option. But 2007 Corvette does, which should use the same ECM service number. But but, you don't have a way to change to that OS/VIN if your only tool is HPTuners, a change like that requires GM SPS/Techline subscription & compatible J2534 tool. But but but, making that change would give you a proper non-auto-trans OS that's able to read a VSS and isn't constantly wondering what happened to its friend the TCM. Idle will work better, and all kinds of other things too. You might have to change the pedal/APP sensor, I don't know the full story on what interchanges for each OS/year. The time for dealing with problems like this is before you even get started.

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This isnt really the path I want to go down. I dont have the budget to buy a pedal/tb and license another vin. I would like to make what I got work.

Another thing I noticed with my ECM thats different than other E38s without VSS - the vehicle speed shows 0 - not 158mph. I cant access my tune file here but if I remember correctly VSS setting was wheel sensor? Perhaps unlike other E38 A6 OS I can add VSS direct to the ECM without CANBUS.

Well, I think I've done the most I can do for tuning without a driveshaft. It should be here friday im hoping and I will trailer the car somewhere I can get under load and up into the rpm.

Couple questions --

1. Would there be benefit to copying values for the idle airflow tables from a manual 6.2 camaro as a starting point?
2. Without TCM what "gear" does the ECM think its in - for table reference purpose
3. How could I safely take power out of the car - my wife is a first time driver and I would like to let her get used to the launch (dial in RT) without the top end mph.

Thanks all,

-Brennan

Don't copy out of another tune file. That is a recipe for problems.

What would be the safest way to remove power from the car to allow a new driver to get comfortable.

Ideally would be limiting throttle opening to 50-60% but ive read that can cause issues with REP mode.

Has anyone been down the road of trying to slow a car down?

- would it be best to use torque management?

Hello,
I'm all ears in this matter as i have to do pretty much the same for my first registration.

/Christian

Take ignition lead away. Start with cutting it in half at the moderate load and above points in your timing table for the first test. Depending on how much power you need to cut, it may take removing significantly more timing and then some fuel. You could always drop the rev limiter down also.

Quote:

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Originally Posted by abc

Take ignition lead away. Start with cutting it in half at the moderate load and above points in your timing table for the first test. Depending on how much power you need to cut, it may take removing significantly more timing and then some fuel. You could always drop the rev limiter down also.

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I really dont want it banging on the rev limiter the whole way down the track. I think I can get Torque management to use the ETC to cut power.