2 BAR Tuning Problems

So, I am having throttle/tuning issue's with the Edelbrock E-Force supercharger that i installed on my 2004 Cadillac CTS-V, with the stock LS6. Here's what I have so far:

- Converted from 78mm Throttle body to 90mm throttle body using the Caspers harness
- Removed the MAF and installed a 2 BAR SD tune
- Set the correct injector data (Deka sort height, 60lbs)
Total Mods:
- 2300 TVS supercharger with 3.25" pulley (good to 10 PSI)
- Kooks long tube headers (1 7/8") with tuning pipes at the moment.
- DW 300 fuel pump
- stock LS6 cam with .625" valve springs and hardened push rods

The two main problems that I have is that the engine seems to buck pretty bad right at 1500 - 2000 RPM's (feels almost like a dead miss although I know there isn't a miss), and the throttle seems to be really slow to react, somewhat of a delayed reaction. I am wondering if the 90mm throttle body may be opening too much too fast in comparison to the 78mm that it replaced. It almost feels like the throttle and the boost actuator which is vacuum sourced may be pushing/pulling each other, if that makes sense. I played around with a few things, raising the Stoich to 14.4221 seemed to help marginally at first, although this was short lived.

Not really sure if this is a tuning issue or a throttle issue as most of my issues thusfar have been with the throttle (P0068, etc). I ended up turning off the P0068 DTC until I can get the VE dialed in, then go back and reset it.

Anyhow, after the 2000 RPM mark it clears right up and is fine. Its just a low rpm (lugging) issue.

Appreciate any assistance!

Do you have a wideband?
Most cases of bucking/hesitation on FI setups are for lean mixtures. SC add a lot of low end torque to a stock engine so it needs more fuel.
Increase VE in part throttle areas by 20% and install a wideband, then tune from there

Quote:

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Originally Posted by Montecarlodrag

Do you have a wideband?
Most cases of bucking/hesitation on FI setups are for lean mixtures. SC add a lot of low end torque to a stock engine so it needs more fuel.
Increase VE in part throttle areas by 20% and install a wideband, then tune from there

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Thanks! Yes, wideband has already been installed along with new GM O2 sensors. I am using the "Lambda Error" PID to adjust the VE tables; which are now in the "0.98" range or so which is just a tad rich in the area's where i'm having issue's.

Comparing the value's that I have now against the stock tune, i'm right at 19% over the stock value's, which falls in line with the advice you gave. However, the Lambda Error is saying this is a tad too rich. Should I try changing the Stoich in order to get it where it feels better and go from there?

Oh, stock tune included for comparison. Thanks!

If it's a little rich with no lean spikes, then fuel is not the issue.
However, there are big timing drops in your datalog, even to negative advance. That may be the issue, try to find why the PCM is pulling timing

EDIT: I opened your tune and you pulled a lot of timing in low RPM, up to -12 deg. Even more in high RPM areas.
Why did you take so much timing? add a few degrees and it will improve.

here is a timing config.

Quote:

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Originally Posted by Montecarlodrag

If it's a little rich with no lean spikes, then fuel is not the issue.
However, there are big timing drops in your datalog, even to negative advance. That may be the issue, try to find why the PCM is pulling timing

EDIT: I opened your tune and you pulled a lot of timing in low RPM, up to -12 deg. Even more in high RPM areas.
Why did you take so much timing? add a few degrees and it will improve.

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Thanks, Monte! Yeah, as soon as you said that the first thing I did was to zero out the burst knock cells, which improved the problem by about 90%.:doh:

Then I started over on the timing tables, I think I based them off the low octane map for some damn reason...guess you're not supposed to be setting up a startup tune at 2 am, LOL!

I think I was dead set on finding an actual cause and viewed this as more of an effect, if that makes sense. Anyhow, thanks for getting me on the right track.

Quote:

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Originally Posted by robbyredneck

here is a timing config.

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Thanks, Robby! Will put it to good use!

Ok...so no matter how much I adjusted the timing I still could not get it 100% right...there was still a little hesitation, although not 100% of the time. To make things harder to interpret, the log showed a mirror image between when it felt as if it was hesitating and when it did not (timing cfg).

As a last resort, I adjusted the "Desired Throttle Area" (Airflow-->ETC tab) above the original values and it went away completely! The only thing I can imagine is that the blower was working against the throttle blade during low (5-10%) commanded throttle, trying to close it.

This makes sense in my mind as this is a rather large blower for a smaller displacement engine, and the boost comes on very quick. If the MAP is calibrated and reading correctly (which I believe it is), it looks as if I have about 6 PSI of boost available at 1600 - 2000 RPM.

Forgot to post the tune, still working on it though and any additional comments are welcome. It's almost to the point where I feel comfortable taking it to the dyno and see what it will do!

take a look at your timming map in 3D all those dips and spikes are going to affect how smooth your engine will work
if you take the time to smooth those areas out you will be surprised how much smoother your engine will run
yes it's a PITA job but worth the effort

The burst knock Enable Delta Cyl air must not be zero. Use stock values and raise them. If you want to completely disable max them.

Quote:

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Originally Posted by zok

take a look at your timming map in 3D all those dips and spikes are going to affect how smooth your engine will work
if you take the time to smooth those areas out you will be surprised how much smoother your engine will run
yes it's a PITA job but worth the effort

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Yeah, still working on that! I have been mainly concerned with getting the drivability bugs worked out before I start combing through everything making fine adjustments.

Quote:

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Originally Posted by Montecarlodrag

The burst knock Enable Delta Cyl air must not be zero. Use stock values and raise them. If you want to completely disable max them.

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Thanks! Did not know that!

Timing advance spikes and valleys cause drivability issues because the transition from one cell to another is not smooth.
Imagine you are cuising at 1400 RPM with 20 deg advance, then you give it more gas to pass and the PCM references the next cell which has 16 deg. That difference make the engine hesistate.

Have somebody drive the vehicle and watch how the scanner histogram populates the cells. It will give you an idea of the "path" timing takes as the car accelerates.