Help with Cam LS3 Surge 1500-1800rpms

[speedjunction]

Hello

I have a surge while cruising.

Vehicle is a 1971 Chevelle Ls3 4l80e BTR Stage 2 V2 Cam.

I calibrated the MAF and VE LTFT below 5% and smoothed the ignition table.

But I still have a surge at 1500rpm when cruising.

You can see it in the last third of the scan

Can you help me or have another idea ?

Thanks for Help 1971_Chevelle_LS3_4l80e_BTR_CAM_Final.hpt1971_Chevelle_Ls3_4l80e_BTR_Cam Probefahrt cruise.hpl

[edcmat-l1]

Fuel trims. Injector timing will help with that some but not sure if it will ever go away 100%. Quick way to test if it's the trims is turn them off while it's doing it. Use your scanner controls and click closed loop off while it's happening. Then turn it back on.

It's also possible some of it is caused by intake reversion, depending on the placement of the MAF. A good way to test this is put it in speed density and see if it runs better. C6 Corvettes always run better in SD when you put a cam in them because the MAF is right in front of the throttle body.

[blindsquirrel]

That's some of the goofiest Power Enrich settings I've ever seen.

[Alvin]

Hello

I have a surge while cruising.

Vehicle is a 1971 Chevelle Ls3 4l80e BTR Stage 2 V2 Cam.

I calibrated the MAF and VE LTFT below 5% and smoothed the ignition table.

But I still have a surge at 1500rpm when cruising.

You can see it in the last third of the scan

Can you help me or have another idea ?

Thanks for Help 1971_Chevelle_LS3_4l80e_BTR_CAM_Final.hpt1971_Chevelle_Ls3_4l80e_BTR_Cam Probefahrt cruise.hpl

I believe it is the fuel trims swinging. You can increase the integrator delay and reduce the proportional controls on the o2 sensor tab.

It may also have MAF noise causing it. Does it do it in speed density?

[speedjunction]

Fuel trims. Injector timing will help with that some but not sure if it will ever go away 100%. Quick way to test if it's the trims is turn them off while it's doing it. Use your scanner controls and click closed loop off while it's happening. Then turn it back on.

It's also possible some of it is caused by intake reversion, depending on the placement of the MAF. A good way to test this is put it in speed density and see if it runs better. C6 Corvettes always run better in SD when you put a cam in them because the MAF is right in front of the throttle body.

Thank you for your help

When I calibrated the VE and drive without MAF in open loop it was gone completely.

There is a K&N Intake installed (2012 Camaro )

If I just turn off the closed loop it is ok but not gone

[speedjunction]

I believe it is the fuel trims swinging. You can increase the integrator delay and reduce the proportional controls on the o2 sensor tab.

It may also have MAF noise causing it. Does it do it in speed density?

Thanks for the help

I will try that

[LS ROB]

What are the specs on that stage 2 cam? Longer logs will allow the trims to settle a bit more. I'd shoot for a minimum 25min per log if possible due to rich after flash. I believe the tune just needs to be dialed in. The closer it gets, the smoother it will be. Also, like Ed said, reversion could be at play. What kind of intake tube for the MAF do you have? I adjusted the PE throttle settings and tweaked the idle rpm if you want to flash this in. I did not feel comfortable changing VVE or MAF from a 3 minute log.


1971_Chevelle_LS3_4l80e_BTR_CAM_Final-1.hpt

[speedjunction]

Thanks for your help

I will adjust the PE mode, I have not seen it.

BTR LS3 STAGE 2 V2 CAMSHAFT
221/24X, .619/.617, 113 LSA

Intake tube is K&N LS3 ( Camaro 2012)

I just did a quick scan to show the problem.

Because otherwise the car runs great.