[KingLT1]

The ECU uses the MAF all the time for fuel control. I think what you mean is the transition between closed to open loop PE mode.

[teesee150]

Originally Posted by Joshinator99

If you have a big cam, my advice is to immediately install the electronic Smoothboost bypass valve. Solves all these silly vacuum bypass-related idle and driveability issues. It’s available for the 2.9 Whipple and pretty easy to adapt to the new 3.0 too.

Full thread about it here:
https://www.camaro6.com/forums/showt...ht=Smoothboost

That's pretty interesting, haven't seen that before.

Was hoping to find a cheap fix vs a $1000. If I can't figure something out, I'll probably pick this up.

I found a source for vacuum line restrictors, so I bought a bunch from .007" to .025" to see if it will slow down the action of the bypass valve

[teesee150]

Originally Posted by Jhunsberger

In my case I got this sorted several years ago. The rough spot at 2500-3000 rpm was caused by the original tune switching between MAF and speed density, this is where the transition was. After I had someone else re-tune it the issue completely went away and drivability was way better.

I've had four different tuners work on this setup so far. I've been from horrible to not so bad, but they all said the bypass is causing the problem exactly as described in the first post. I'm wondering if this more pronounced with a manual transmission as the OP and I both have manuals.

I can usually drive around the problem, but after dumping this money into the car, I shouldnt have to worry about low speed driving like I do.

[Joshinator99]

Originally Posted by teesee150

I've had four different tuners work on this setup so far. I've been from horrible to not so bad, but they all said the bypass is causing the problem exactly as described in the first post. I'm wondering if this more pronounced with a manual transmission as the OP and I both have manuals.

I can usually drive around the problem, but after dumping this money into the car, I shouldnt have to worry about low speed driving like I do.

The Whipple bypass valve is an issue that I messed with for a while before seeing the light, and especially true if you’re running a cam. Relying on vacuum signal for boost control is simply inferior to an electronic one that sees what you’re actually requesting for power (Smoothboost uses pedal position sensor signal). Plus the actuator gives you more positive boost control vs relying on a spring. It’s essentially carb vs EFI in terms of technology.

[teesee150]

Originally Posted by Joshinator99

The Whipple bypass valve is an issue that I messed with for a while before seeing the light, and especially true if you’re running a cam. Relying on vacuum signal for boost control is simply inferior to an electronic one that sees what you’re actually requesting for power (Smoothboost uses pedal position sensor signal). Plus the actuator gives you more positive boost control vs relying on a spring. It’s essentially carb vs EFI in terms of technology.

Did you have to retune the car after installing the smoothboost? I'm not looking to run anymore boost or limit boost for that matter as I'm already out of fuel on e85. I would just want it to eliminate the issues with the bypass slamming shut.

[Joshinator99]

Originally Posted by teesee150

Did you have to retune the car after installing the smoothboost? I'm not looking to run anymore boost or limit boost for that matter as I'm already out of fuel on e85. I would just want it to eliminate the issues with the bypass slamming shut.

I only retuned because I had swapped pulleys for more boost at the same time as the Smoothboost install back when I had my 2.9 Whipple. But I suspect your existing tune would be fine as is as you’re not making any major airflow changes.

[shinysun]

Originally Posted by teesee150

Did you have to retune the car after installing the smoothboost? I'm not looking to run anymore boost or limit boost for that matter as I'm already out of fuel on e85. I would just want it to eliminate the issues with the bypass slamming shut.

Go with Smoothboost. Highly recommand for cam cars or high boosted PD blower cars. Simply all issues just gone.

[teesee150]

I just wanted to come back and post my results with the inline restrictor.

I bought some restrictors from here in various sizes: https://www.ocpneumatics.com/orifice...strictor-kits/

I got the 1/8 barbed restrictors and used 1/4 - 1/8 vacuum line adapters to splice them inline to the boost bypass.

Running the .020 restrictor 100% solved every drivability issue I had with the Whipple. I am beyond ecstatic with how the car drives now.

I used to have to drive really slow and wait for the boost to kick in or give it a decent amount of throttle and break the tire loose. Anything in between would cause the car to studder/hesitate when the bypass valve closed. My AFR would go to 1.2-1.3 and the car would stumble until I let off the gas and got back on it. Made it incredibly frustrating to drive.

All of that nonsense is gone now. I took it for a drive and was intentionally trying to get it to stumble and was never able to replicate the problem with the restrictor in place. Now I can just roll into the throttle and the car just goes like mad. I was seriously considering selling the car or take the whipple off because it was so frustrating to drive.

Really glad I tried these before I dumped $1000 into the smoothboost.

[Schlok]

Wow, what a fix, very nice work!

[BlackbeastSS2]

Originally Posted by teesee150

Really glad I tried these before I dumped $1000 into the smoothboost.