Stall when coming to stop, LM7 5.3 Turbo TH400 swap Speed Density 2BAR

[phtcbra]

Only one MAP sensor PID should be present. Keep the 2 bar, remove the SAE.

Should probably start over with the stock spark tables.

Thank you for this information, I wasn't sure exactly which PID was best to log, so I grabbed them both to make sure I have something, but will adjust my settings accordingly.

I was JUST thinking about the spark tables this morning as I went back to the stock fuel and have had very good luck. I am in agreement and will load up the stock stuff today and see how it goes. Thank you for the assistance.

[phtcbra]

If you have a standard style Neutral safety switch it is very easy to use a relay and a diode to give the PCM a proper Park/Neutral switch that can be utilized using the single wire P/N switch input like the 4th generation F-cars used. Open the instructions and they have a diagram of how to do it. Could buy the kit but I never have because I can duplicate it with $10 worth of pieces.

https://painlessperformance.com/prod...part-no-60122/

My last conversion to a P59 was on a 1987 G20 that had a P/N switch already wired through the C100 plug on the firewall for the old TBI ECM so I did not even have to use this method, just tied the existing wire to the P59. Ties to C1 Blue connector pin 34. This enables the idle airflow tables and idle speed settings for Park to be enabled. Without the switch the PCM always runs on the Drive settings. With a little tuning on the Park and Drive settings the idle will not drop or race when the transmission is shifted. Big help for a tendency mine had stalling going into reverse. On my cammed L31 350 it helped to add a bit of timing in the Drive idle timing table as well. The PCM bumps the timing up from 20* to 24* when I put it into Drive to help offset the increased load. The VSS enables all the idle transition routines for better IAC control as well when coming to a stop. I find better sucess giving the PCM the inputs it needs rather than trying to tune around them. That transmission option switch that is not supposed to do anything also disabled all the transmission DTCs by turning off the electronic transmission code in the PCM when I set it to non-computerized automatic. I do have a non-computerized segment for the 8100s in the big trucks that used Allison 545s for both the 0411 and P59 but I have not had to use it yet.

I have swapped this into a 1966 Chevy II Nova, and am using the stock factory style GM Neutral safety switch, but I have it wired into the STARTER RELAY circuit as the car is not exactly stock, but still using some stock components for safety and drivability. It is just a switch that slides on the column that creates a contact when in P or N allowing the starter relay signal to be momentarily engaged.

To confirm, the P/N signal is a ground signal, correct? I have the parts to build that exact harness here at home, so I'll get on that today. I'll do some digging over at LT1swap.com too and see, and the good ol google try but I just wanted to confirm with you as you've clearly done this before.

I knew I really appreciate the help and will report back with my findings/sucess'. Thanks

[Fast4.7]

I have swapped this into a 1966 Chevy II Nova, and am using the stock factory style GM Neutral safety switch, but I have it wired into the STARTER RELAY circuit as the car is not exactly stock, but still using some stock components for safety and drivability. It is just a switch that slides on the column that creates a contact when in P or N allowing the starter relay signal to be momentarily engaged.

To confirm, the P/N signal is a ground signal, correct? I have the parts to build that exact harness here at home, so I'll get on that today. I'll do some digging over at LT1swap.com too and see, and the good ol google try but I just wanted to confirm with you as you've clearly done this before.

I knew I really appreciate the help and will report back with my findings/sucess'. Thanks

The P/N switch is a ground signal, hence the need for the diode and relay setup. The diode blocks the possibility of 12V power being applied to the PCM during cranking. I have done the P/N switch sucessfully on several setups.

[phtcbra]

Just wired this up... more to come..

[phtcbra]

Go Ive got the P/N Relay wired correctly with the diode terminals the right way 85 POS 12V sig and 86 GRND for the coil an am not getting any change. Some times I get a Park signal when I start up but about 3-5 seconds after running it switched to D4, with out the car being put into gear..

Ive checked wiring, its correct.
Swapped Relay, same outcome.
Verified relay is clicking, it is.
Verified Ground signal coming out of relay going to ECU. Its there on Pin 34 of Blue connector.
Even jumped Pin 34 directly to a ground getting rid of relay/neutral safety switch.. Still not triggering the Park/Neutral change in HPTuners..

[phtcbra]

Get an inexpensive Dolphin digital pass through VSS and wire in a P/N switch input. Then set the transmission to non-computerized automatic. It works, I have done it on multiple setups now.

So Im going back over this and now seeing this part of the P/N Fbody switch.. I missed it..

Screenshot 2024-09-23 123516.png

Found another thread from 2015 that led me to getting the right settings under Transmission. P/N Switch works perfect now.

https://forum.hptuners.com/showthrea...tch-won-t-work

[Fast4.7]

So Im going back over this and now seeing this part of the P/N Fbody switch.. I missed it..

Screenshot 2024-09-23 123516.png

Found another thread from 2015 that led me to getting the right settings under Transmission. P/N Switch works perfect now.

https://forum.hptuners.com/showthrea...tch-won-t-work

Good deal, now you can dial in both the P/N and Drive Base Running Airflow tables as any other Automatic would be setup. I also tend to idle mine 50-100 rpm higher in P/N than Drive. Just makes for a smoother transition and where I am here in Texas helps the engine cooling and AC when you are stopped and throw the shifter into Park or Neutral

[phtcbra]

Good deal, now you can dial in both the P/N and Drive Base Running Airflow tables as any other Automatic would be setup. I also tend to idle mine 50-100 rpm higher in P/N than Drive. Just makes for a smoother transition and where I am here in Texas helps the engine cooling and AC when you are stopped and throw the shifter into Park or Neutral

I just got back from taking it out to dial in the new setup. Problem I keep running into is right away I get a P1689 Delivered Torque Circuit Fault DTC which throws the car into limp mode. I've had this code come up before the new settings, but it wasn't until I got to 40-50% throttle from a stop and the car would creep into boost areas. I am going to post a log/tune as I tried to "Remove" whatever Torque settings/abuse settings, but from previous tries I never had any luck. Could it be from the "Non-Electronic" Transmission setting from getting the P/N Circuit to work?

[phtcbra]

Here's the tune.. And two logs.. what's weird is in the Log Details it doesnt show the P1689 Delivered Torque Fault.. WTF

NOVA Tune 2BAR MOD BS3.hpt

LOG3 VE MOD7 MOST STOCK.hpl

LOG3 VE MOD7 MOST CRUISE.hpl

[abc]

https://www.corvetteforum.com/forums...this-code.html

I don't know if this offers any help but maybe food for thought. I didn't go back and study your .hpt but are you running SD only? I assume from the help you have been getting they will know an easy way to bypass this issue. Right now I also assume the PCM is looking for a report back from the TCM of delivered torque and of course it's not there?

[phtcbra]

https://www.corvetteforum.com/forums...this-code.html

I don't know if this offers any help but maybe food for thought. I didn't go back and study your .hpt but are you running SD only? I assume from the help you have been getting they will know an easy way to bypass this issue. Right now I also assume the PCM is looking for a report back from the TCM of delivered torque and of course it's not there?

Correct, SD only, and Segment for Transmission is still 4L60E, but just switched the settings to Non-Electric Controlled Transmission and now the error comes up all the time. When I log, I do see a "Torque Engine Value" and it does move around consistent with throttle. Im just not sure why I can not turn it "off" like so many others.

Thanks for the link, I'll check it out and read up.

[phtcbra]

Good deal, now you can dial in both the P/N and Drive Base Running Airflow tables as any other Automatic would be setup. I also tend to idle mine 50-100 rpm higher in P/N than Drive. Just makes for a smoother transition and where I am here in Texas helps the engine cooling and AC when you are stopped and throw the shifter into Park or Neutral

Just spitballing but is it worth trying to mess with any tuning when I don?t have a speed sensor installed yet? I have the dolphin on the way, but not installed. Just wondering if I should hold off and wait. Starting to think that I should just wait.

[phtcbra]

Got the L96 50 lb injectors in and scaled. Car runs and idles/cruises way better than before, but Im waiting on the Speed Sensor to show today. Hopefully I can get it wired in and get to messing around. More to come.

[blindsquirrel]

Got the L96 50 lb injectors in and scaled.

Not scaled. Scaling is when you alter one thing from its actual true number which is then offset by another thing also altered from actual, typically when an injector is larger than what the flow rate table will allow. There's also airflow scaling but that's a whole other kettle of probably-don't-go-there.

[edcmat-l1]

"Scaled" the term, is often misused because it is fundamentally misunderstood.

[phtcbra]

Correct by both of you, my error.

Injectors installed and correct data entered thanks to BlindSquirrel and his Gen 4 injector data sheet.

Appreciate you guys keeping me in line.

[phtcbra]

Update: Got VSS working.

Here's the latest Tune, just a cruise/idle one. Will continue to adjust VE map when available. If anyone has any suggestions, I am all ears.

NOVA Tune 2BAR MOD 101241.hpt

LOG 101241.hpl

[SiriusC1024]

Are you only paying attention to STFT's or something? Look at LTFT's calling for all that fuel.

[phtcbra]

Are you only paying attention to STFT's or something? Look at LTFT's calling for all that fuel.

Well I'm trying to pay attention to everything, but you pointed out something I was noticing too. I've been doing some reading on the subject and am wondering if I am not going on a long enough drive for them to fully come down (to under 10%, but shooting for the +- 5%. I had reset the LTFT at the beginning of this drive out ( a good 10-15 minutes of driving / idling was for adjusting the VSS settings to get it right ) and the log I posted was from the last short drive home after.

How long of a drive is a good LOG / time for LTFT to be accurate?

My next step is going to be a nice long 30 minute log/drive to see where things go and post up that log.

[SiriusC1024]

They won't come down. STFT's are close. Try LTFT+STFT on the corrections. Clear LTFT's after each tune update.