6.2 Nova Swap Will Not Idle

[JamesTheriot]

Trying to help a friend tune his car.

77 Nova full swap. 6.0 block bored .060 over. BTR stage 3 cam, Fast Lsxr Intake manifold, Fast 102mm Throttle body(cable), Long tubes, Standalone Engine harness with stock 01 Suburban ECU. 799 Heads. Approx 11:1 compression.

I've tuned several other vehicles with little to no issues, but having a hard time here. Car will fire up great but within a few seconds die right out. We have tried opening the throttle more, adding fuel, taking away fuel, changing idle spark, all with no luck. I've got to be missing something simple.

I went step by step through another forum members startup and idle airflow guide and still no luck.

When it does start, moving the throttle blade makes almost ZERO response.

Attatching the Current tune and a startup log. The second start I try to give to throttle so that you guys can see that too.




NOVACURRENT V0013 airflow tuning, inj data.hpt

2 start attempts.hpl

[5FDP]

You didn't change the system options for the DBC throttle body. The tune still thinks the DBW throttle is installed.

[JamesTheriot]

You didn't change the system options for the DBC throttle body. The tune still thinks the DBW throttle is installed.

I was told this pcm came from a dbc truck. I didn't even think to look at that.

[JamesTheriot]

I was told this pcm came from a dbc truck. I didn't even think to look at that.

That made some difference but still does not run any longer.

[5FDP]

Looks like the MAF isn't working.

If you delete the MAF sensor you need to set it to run in speed density. Set the MAF fail high to 0hz and set the 3 MAF dtc's to MIL on first error.

Who's injectors are you running and did you keep the stock MAP that a 2001 Suburban would use?

[SiriusC1024]

You set it to OL, but there's no wideband. Re-enable STFT and try.

You goofed with idle RPM. Spark overspeed correction is pulling spark too low.

The idle is high because BRAF is letting air in for warmup. BRAF will be too low once up to temp. Log Idle Adapt (STIT).

EGR DTC's don't match EGR Spark and Airflow tables.

[edcmat-l1]

Pretty sure you can't just flip the system switch from DBW to DBC. You have to do a write entire with a DBC OS. Otherwise I don't think it will activate the IAC drivers.

Need to flash that with an F body OS.

[Alvin]

Yeah you need to write entire with a OS that will be compatible with that PCM and is meant for cable throttle bodies. Turning the switch on and off doesn't work like that.

[JamesTheriot]

@5FDP .. The MAF isnt working because I have it unplugged. I ended up failing it and the car would idle and stay running.
The injectors are used stock LS3 injectors.

@serius.. I dont remember turning off STFT, I will look into that. I turned off LTFT for sure so that I could try to do some short logs to adjust the VE table.


@edcmat ..I will try flashing the Fbody settings to it today and post another log.

The car is at my buddys shop and I only get to by there every other day or so for about an hour.

Since the last post we failed the maf and the car would stay on but had some trouble blipping the throttle and coming down from where you blip it. We ended up unplugging the IAC and it made zero difference to how the car was acting so I'm sure we have some type of OS mix up going on now.

Will update tonight or tommorrow.

[edcmat-l1]

@edcmat ..I will try flashing the Fbody settings to it today and post another log.

Not just the "settings" you need to do a write entire with a 01-02 F body OS.

[SiriusC1024]

Not just the "settings" you need to do a write entire with a 01-02 F body OS.

Will that screw with ABS or SRS/Airbags? Have to keep the same year and compatible VIN or no?

[gtstorey]

Will that screw with ABS or SRS/Airbags? Have to keep the same year and compatible VIN or no?

Swap vehicle

[SiriusC1024]

Haha again Still though is it the case?

[JamesTheriot]

Current situation. Starts and idles good, beginning to take throttle better with every VE adjustment, I can not get it to catch the idle correctly after you rev it, and it hangs up pretty bad.

This is my first time tuning with a bigger manifold and throttle body and I think thats why I'm having such a hard time.


CURRENT, NO MAF, STILL DYING ON DECEL.hpl

NOVACURRENT V0027 FBODY FUEL, THROTTLE CRACKER.hpt

[JamesTheriot]

Bump. we got better injector data for what we have and that cleared alot of issues. Right not we can't get the adaptive idle to catch when we let off of the gas. I've tried using the follower, spark underpseed, and adaptive idle tables but none of them seem to make a difference.

RUNNING BETTER, WONT CATCH IDLE.hpl

NOVACURRENT V00 40.hpt

[SiriusC1024]

Mess with idle last. Mess with adaptives last of last. Put throttle cracker, follower, adaptives, etc. back to stock.

The injector data isn't correct. IFR is for returnless, but offset is for return.

After that tune VE. Put idle spark at 18 degrees up to 800rpm by 0.28 cylair. Setup the idle curve correctly. Shouldn't be 900rpm across. Do you have an EGR? Airflow and spark tables say you do.

Put base spark back to stock. When you give it gas off idle spark drops from 26* idle to 16* base. That's backwards.

[edcmat-l1]

Will that screw with ABS or SRS/Airbags? Have to keep the same year and compatible VIN or no?

Sorry, late to the party. Yes, you can't just flash an F body OS to a DBW pickup truck. The rest of the truck won't be happy about it.