Ported Plenum Now Code 55

[Aurora40]

Supposedly the car will be limited to 5,000 rpm by fuel cutoff once code 61 is set. You seemed to be able to hit 6k+ though. Your scan doesn't show the O2 values. I assume they are ok (high 800's or 900's mV) up until it commands the secondaries closed again and cuts the fueling in half?

Do you want to fix it totally by tuning? Otherwise, I'd think an easy fix would be to route the secondary actuator to the secondary MAP sensor. That way the ECM will think they are opening properly.

I thought one of the "tune" fixes though was to enable the secondaries all the time. Like to set the opening criteria such that the ECM always thinks they are open. That wouldn't solve the issue of it seeing no vacuum on the secondary map sensor, but it at least would not have your ECM performing these transitions from open to closed when in fact they are open all the time.

It sounds like currently your secondary injectors are only used under hard throttle. I wouldn't think that would result in the smoothest operation? But I dunno, I'm just speculating.

[XfireZ51]

Bob,

O2 sensors are in the 900mv range until injectors are shutoff. When I unplug line from Scdy Vac Pump, pump operates with Key On, Engine Off. When I plug line back in, pump shuts off, indicating vacuum present.
Checked the under plenum vacuum with Mighty Vac. Pumped to 20" Hg.
Vacuum held, albeit lost about 2" in a minute. Not sure how tight its supposed to be.

As for the "tune fix", the PT TPS% Close and Open tables are set to 0 along with PT Scdy Delay.

[Aurora40]

Originally Posted by XfireZ51

As for the "tune fix", the PT TPS% Close and Open tables are set to 0 along with PT Scdy Delay.

I really know little about the tune stuff. However, just from looking at your scan, doesn't it look like it's not actually doing what you are describing? You can see the port throttles commanded on right around when your throttle opening goes to ~ 100%.

If it was doing what you say, they should have already been commanded on from when you first fired it up. Unless I'm misunderstanding something.

At least you know what the lean condition code is for now, though.

Edit: My bad, your port throttles do appear to be open. It's the secondary fuel pump that doesn't come on until you gun it. I wonder if just adjusting the PT opening params isn't the full fix? I mean, what you really want is to have all 16 injectors firing all the time, right? It kind of seems like opeing the PT's is just part of a larger "secondary active" type operation. I mean, it's still expecting the vacuum to change on the PT vacuum sensor, even though they've been open the whole time. Sounds like it should be a great learning experience about GM's control programs though! Sorry I don't know more to be helpful.

[Aurora40]

Originally Posted by XfireZ51

O2 sensors are in the 900mv range until injectors are shutoff. When I unplug line from Scdy Vac Pump, pump operates with Key On, Engine Off. When I plug line back in, pump shuts off, indicating vacuum present.
Checked the under plenum vacuum with Mighty Vac. Pumped to 20" Hg.
Vacuum held, albeit lost about 2" in a minute. Not sure how tight its supposed to be.

Actually, can you explain more? I assumed you removed all that stuff. So how exactly did you go about removing the secondary stuff? Are the actuators still in there? It's good the thing holds a vacuum when you test it. However, that is in "closed" position I'd guess. When it commands the secondary solenoid to open, perhaps that's when it has a leak? What I mean is, key on engine off you are simply testing that the solenoid, the vacuum reservoir, and the lines up to them don't leak. Anything past the solenoid wouldn't be tested in that case

I'm just taking wild guesses though. If you could explain how exactly the vacuum system is currently configured, that might help.

P.S. is "actuator" and "solenoid" the right word? I'm referring to the vacuum solenoid that is electronically controlled, and provides vacuum to the secondary actuators to open the throttles, or opens them to the atmosphere to close them. The "actuator" being those two cylinder things, one on each side, with the diaphram and connector on it. When they have vacuum, they pull on the connector, thus pulling open the secondary throttle blades. I should crack open my FSM to make sure I'm not just using confusing terminology...

[XfireZ51]

Bob,

All good questions. Part of the reason for the forum is to learn from each other. As for the config., everything is as it was except that the port throttle blades have been removed. I originally took them off to clean them, then tried putting them back on and realized they needed to be centered and the levers aligned etc. All so you can turn a "valet" key.
In trying to undo the screws and center the throttle plates, the torx head stripped on several blades. I had to drill the heads off in order to remove the blades. So I said "the hell with it". Not worth the hassle.
I did try checking vacuum from the sensor back and got none.

[lbszr]

Originally Posted by XfireZ51

Bob,

All good questions. Part of the reason for the forum is to learn from each other. As for the config., everything is as it was except that the port throttle blades have been removed. I originally took them off to clean them, then tried putting them back on and realized they needed to be centered and the levers aligned etc. All so you can turn a "valet" key.
In trying to undo the screws and center the throttle plates, the torx head stripped on several blades. I had to drill the heads off in order to remove the blades. So I said "the hell with it". Not worth the hassle.
I did try checking vacuum from the sensor back and got none.

Too lazy to look at book but if 61 is set and locks out sec. then there would be no vaccum at sensor, might have to reset.

Don't know how to do chips but Mines set for sec. injecters open just off idle around 1%, by watching scanner they open by just touching accelerater and thats when the vaccum is sent to the sensor also.

Sec. fuel pump doesn't come on till about 4000rpm. or below 180 degree coolant temp.

Unless you have it programed to remove solonoid and vaccum pump and plumbing which is how mine is now but don't really know what's going in this case, inj still come on just off idle though.

Looked into doing the chip a while back and got a headache,

I know you have to trick the ecm somehow to not get 61.

[XfireZ51]

Well as usual, the Greek cavalry comes to the rescue. PeteZR1 had me bypass everything under the plenum and go directly to the secondary throttle sensor. No more Fuel System Lean code 55. So the issue is somewhere under the plenum. Possibly the solenoid or vacuum reservoir.
So do I pull the plenum and check it out or wait till after BG?

[lbszr]

Sure would be a long drive on primary's

[Pete]

Dom, any seat of the pants power differance.

Pete

[XfireZ51]

Originally Posted by Pete

Dom, any seat of the pants power differance.

Pete

Pete,

The problem is that I've been driving a Vibe GT for the last 3-4 months.
BUT, I will say that the car feels as if it just keeps pulling. The higher the rpm, the faster it gets. I've got a dyno session scheduled for next Saturday at Street Stuff.