Open loop OK, but closed loop goes crazy (Procharged LS)

[Pekka_Perkeles]

This car was previously tuned by someone with bad results.

Original tooned tune: 01 luettu autosta.hpt

This is the setup now:

- 6.1 LS engine with 10.5:1 compression ratio
- BTR Stage 2 supercharged cam
- Procharger (not very big) with 8-belt rib & air-water IC
- boost-referenced fuel system
- 1350 cc fuel injectors (at 44 psi or so, perhaps Bosch-based)
- E85 fuel
- 2 bar COS
- headers

I tried to run it at closed loop, but trims just go crazy during normal driving. Only at idle it seems to be as it should.

So I went with open loop and used car's own wideband to get 2 Bar VE somewhere where it should be. But, as soon as I force Closed Loop with Scanner Controls, STFT just goes from -25 to +25 and Wideband confirms that.

Open loop tune (in the end I'm forcing Closed Loop: 502 ve idlealueen.hpt



Open loop log with closed loop activated just at the end: 35 first open loop then activate lambdA.hpl

I think it's something in the tune that makes both lambdas go crazy.

We did a smoke test in the intake side but no leaks at least there. Lambdas are two years old.

[blindsquirrel]

Offset vs Volts vs VAC table is not correct for a referenced regulator. In fact, none of the injector data has been changed other than flow rate.

What MAP sensor is in the car? I'm unaware of any sensor that has actual specs of 200.00/10.33, that's just the default auto-filled values with the 2-bar OS.

[Pekka_Perkeles]

I forgot to mention that I used hopefully a stock -99 Corvette to change most of the tune back to stock and then made some changes by myself. I forgot to change cylinder volume though, so VE is a bit too high now.

Stock -99 LS1 Corvette tune: 23402011199.hpt

[Pekka_Perkeles]

Offset vs Volts vs VAC table is not correct for a referenced regulator. In fact, none of the injector data has been changed other than flow rate.

Yep, forgot that one (for regulated pressure) when trying to figure out what the heck is causing this.

For other injector data, I need to see what can be done.

What MAP sensor is in the car? I'm unaware of any sensor that has actual specs of 200.00/10.33, that's just the default auto-filled values with the 2-bar OS.

Good, question. I don't know.

Since this is Firebird and MAP is somewhere back in the manifold (if I recall right), I need to ask that from the builder or customer.

[edcmat-l1]

Make sure the O2s aren't crossed. Easy to do in the C5s. Seen it a bunch of times. Can't say that's what the pattern looks like but it's odd enough that's a possible cause.

[Pekka_Perkeles]

Make sure the O2s aren't crossed. Easy to do in the C5s. Seen it a bunch of times. Can't say that's what the pattern looks like but it's odd enough that's a possible cause.

Yep!

I even called the customer to explain to him that those front lambdas must be crossed.

But they weren't. I checked it by disconnecting one and got a fault code from that side as well.

Very strange, indeed.

[gtstorey]

Injector harness swapped?

[blindsquirrel]

They usually won't switch at all ever when swapped bank to bank, they just keep drifting in opposite directions forever (or until it switches into a different FTC and starts over again).

[blindsquirrel]

The smaller the PW, the more impact wrong Offset & SPA will have. At bigger PWs those are a much smaller proportion of the on-time so makes little difference to anything.

[edcmat-l1]

They usually won't switch at all ever when swapped bank to bank, they just keep drifting in opposite directions forever (or until it switches into a different FTC and starts over again).

That's true.

The smaller the PW, the more impact wrong Offset & SPA will have. At bigger PWs those are a much smaller proportion of the on-time so makes little difference to anything.

That's very possible the data is off so bad it goes into an exaggerated swing.

[Pekka_Perkeles]

Thank you everyone for this.

I think that's the main issue and I will verify it tomorrow. Pretty easy just to unplug one injector and see what error code it sets.

[edcmat-l1]

Oh shit I missed the 1350 injectors. Yeah, it's in the data.

[Alvin]

Offset vs Volts vs VAC table is not correct for a referenced regulator. In fact, none of the injector data has been changed other than flow rate.

What MAP sensor is in the car? I'm unaware of any sensor that has actual specs of 200.00/10.33, that's just the default auto-filled values with the 2-bar OS.

The original 2 bar brick map sensor used in the 80's early 90's used that offset and scalar.

[Pekka_Perkeles]

The smaller the PW, the more impact wrong Offset & SPA will have. At bigger PWs those are a much smaller proportion of the on-time so makes little difference to anything.

Exactly!