Why am i not moving in 1st and 2nd?

[Robf]

This question is also posted on the fb group.

I have had an issue with my goblin bogging down when my foot is to the floor in 1st and 2nd gear. The only check engine lights I have were the evap and 2nd 02 sensor as I'm running an afr gauge. I sent the ecu off to get tuned and remove the torque limits, increase rpm redline, remove check engine lights etc. I got it back and it feels better but again from like 3rd gear on. The picture is live data from stand still to 80. I shifted to second at 3k mainly because I wasn't moving and the engine was just increasing rpm without changing speed much. It still seems like the throttle body isn't opening up like it should until I hit 3rd gear. When you launch it in first or second initially it feels like the butterfly wants to open but it just doesn't then it bogs down and does the same thing as stated above.

The throttle position data seems weird as the whole time my foot was buried unless I was shifting. 3rd and 4th feel like an entirely different animal just trying to get the other gears to do the same.

Additional info
The cobalt didn't have this issue.
This was an issue before the tune.
Throttle opens fully when key is in the on position and the pedal is pressed.
It also opens fully on revving the engine in neutral, and in gear with clutch in.
I also added additional data on a second launch foot to the floor.
As you can see 0-50 took 15 seconds and on both sets of data once I hit 50mph everything opened up and it moved.

 

[Ross]

I wonder if it is deliberately tuned that way? My LSJ could use reduced power in 1st and 2nd.

 

[Robf]

I wonder if it is deliberately tuned that way? My LSJ could use reduced power in 1st and 2nd.

The torque limits were turned off by a member of the group. Initially that's what we were thinking as well but that doesn't seem to be the whole story.

 

[Dsteinhorst]

Something is up with your throttle table. Like Ross said, it's almost like it's intentional. Do you have HP Tuners to log with and check tune tables?

 

[Robf]

Something is up with your throttle table. Like Ross said, it's almost like it's intentional. Do you have HP Tuners to log with and check tune tables?

Unfortunately I don't have hp tuners. I don't know how to read or tune. Which is why I sent the ecu off to have it done.

 

[Dsteinhorst]

Your absolute throttle position and MAP tell me your throttle isn't being commanded open all the way. Can your tuner help?

 

[Robf]

Your absolute throttle position and MAP tell me your throttle isn't being commanded open all the way. Can your tuner help?

Oh yeah hes been very helpful. He will post the tune on here and see if it can lead us to something. Are there any parts you can think of that could be causing this? Bad MAF, throttle body, acceleration pedal etc

 

[Ross]

This question is also posted on the fb group.

I have had an issue with my goblin bogging down when my foot is to the floor in 1st and 2nd gear. The only check engine lights I have were the evap and 2nd 02 sensor as I'm running an afr gauge. I sent the ecu off to get tuned and remove the torque limits, increase rpm redline, remove check engine lights etc. I got it back and it feels better but again from like 3rd gear on. The picture is live data from stand still to 80. I shifted to second at 3k mainly because I wasn't moving and the engine was just increasing rpm without changing speed much. It still seems like the throttle body isn't opening up like it should until I hit 3rd gear.

Well the throttle body is just doing what the PCM tells it to do, and the PCM is only seeing "Commanded Throttle" at less than 40%. It only gets up to full throttle around 50MPH. It is like the PCM has put the car in limp mode. Your 0-60 time was over 26 seconds... instead of 4. Ouch.

When you launch it in first or second initially it feels like the butterfly wants to open but it just doesn't then it bogs down and does the same thing as stated above.

The throttle position data seems weird as the whole time my foot was buried unless I was shifting. 3rd and 4th feel like an entirely different animal just trying to get the other gears to do the same.

I agree... throttle position data seems to be limited by the PCM. There is more going here.
Kind of reminds me of when I first started using HP Tuners. Once I saw the data that the PCM was getting, I knew something was wrong with my LSJ. Turns out that the intake manifold pressure was always the same as atmospheric pressure... no boost showing. There were no engine codes being thrown, as the pressure sensor was working, it was just broken from the Cobalt accident that ended it's life, and put it in a Coparts lot. Now the broken pressure sensor was not connected to the intake, but just the air near the intake, which it was reporting to the PCM. New $30 pressure sensor, and my LSJ got 50% more power than before. I though my car was fast, and all of a sudden, it was faster. No engine codes were being thrown, but my LSJ was still not working right.

If you can find a person in Iowa with HP Tuners, they can connect and read your engine data, without having to buy HP Tuners credits/ licence... so free. That would show if any tables are not getting good data.

 

[Robf]

Well the throttle body is just doing what the PCM tells it to do, and the PCM is only seeing "Commanded Throttle" at less than 40%. It only gets up to full throttle around 50MPH. It is like the PCM has put the car in limp mode. Your 0-60 time was over 26 seconds... instead of 4. Ouch.

I agree... throttle position data seems to be limited by the PCM. There is more going here.
Kind of reminds me of when I first started using HP Tuners. Once I saw the data that the PCM was getting, I knew something was wrong with my LSJ. Turns out that the intake manifold pressure was always the same as atmospheric pressure... no boost showing. There were no engine codes being thrown, as the pressure sensor was working, it was just broken from the Cobalt accident that ended it's life, and put it in a Coparts lot. Now the broken pressure sensor was not connected to the intake, but just the air near the intake, which it was reporting to the PCM. New $30 pressure sensor, and my LSJ got 50% more power than before. I though my car was fast, and all of a sudden, it was faster. No engine codes were being thrown, but my LSJ was still not working right.

If you can find a person in Iowa with HP Tuners, they can connect and read your engine data, without having to buy HP Tuners credits/ licence... so free. That would show if any tables are not getting good data.

The thing I'm trying to wrap my head around is when this was the cobalt I never had this issue. I dropped the clutch and it launched. The tune didn't change from cobalt to goblin. Some systems were removed like evap and body control stuff but that was it. I have a tuner that lives about 45 minutes from me that will ride with me and dyno it if I want to. Chuck will post the tune on here in the next couple days and see what you think from there. I wonder what the computer would be sensing to cause the limp issue.

 

[Ross]

The wiring harness being disconnected, moved, and reconnected can cause issues, as can the grounds. Makes it more challenging to figure out what connector is causing the issue. I fought with GM LAN issues for months, now the LAN works, but my radiator fan doesn't.

 

[Robf]

The wiring harness being disconnected, moved, and reconnected can cause issues, as can the grounds. Makes it more challenging to figure out what connector is causing the issue. I fought with GM LAN issues for months, now the LAN works, but my radiator fan doesn't.

I had some issues at the start with a ground that was sheered off that was wrapped up in the old radiator loom. Otherwise I've been pretty issue free other than this limp mode.

 

[Robf]

Well the throttle body is just doing what the PCM tells it to do, and the PCM is only seeing "Commanded Throttle" at less than 40%. It only gets up to full throttle around 50MPH. It is like the PCM has put the car in limp mode. Your 0-60 time was over 26 seconds... instead of 4. Ouch.

I agree... throttle position data seems to be limited by the PCM. There is more going here.
Kind of reminds me of when I first started using HP Tuners. Once I saw the data that the PCM was getting, I knew something was wrong with my LSJ. Turns out that the intake manifold pressure was always the same as atmospheric pressure... no boost showing. There were no engine codes being thrown, as the pressure sensor was working, it was just broken from the Cobalt accident that ended it's life, and put it in a Coparts lot. Now the broken pressure sensor was not connected to the intake, but just the air near the intake, which it was reporting to the PCM. New $30 pressure sensor, and my LSJ got 50% more power than before. I though my car was fast, and all of a sudden, it was faster. No engine codes were being thrown, but my LSJ was still not working right.

If you can find a person in Iowa with HP Tuners, they can connect and read your engine data, without having to buy HP Tuners credits/ licence... so free. That would show if any tables are not getting good data.

Oh also the 0-60 time was 17 seconds give me some credit

 

[Ross]

LOL... well you are correct, and 17 seconds is better. If I would have recorded my 0-60 when I had the intake pressure issue, we could of had a limp mode race.

 

[Robf]

LOL... well you are correct, and 17 seconds is better. If I would have recorded my 0-60 when I had the intake pressure issue, we could of had a limp mode race.

I'll get in contact with the local guy and see if I can get in with him in the near future and see what I can come up with. Any other suggestions other than it being a computer issue?

 

[Gtstorey]

I don't think you are truely in limp or reduced power mode without engine DTCs unless the DTC is turned off in the tune. These can cause REP even if no error is reported. My first step would be to review the tune and turn on all but the obvious DTC's such as evap and 2nd o2.

 

[Robf]

LOL... well you are correct, and 17 seconds is better. If I would have recorded my 0-60 when I had the intake pressure issue, we could of had a limp mode race.

I did some more testing tonight and I may be narrowing down the root cause.
In neutral I have 100 percent control of the butterfly with the pedal.
In first and second gear the issue still remains. So what I did is I started rolling in 1st and skipped 2nd gear right into 3rd the butterfly opened 100 percent on full throttle.

I did replace the clutch, flywheel,slave cylinder as well as the clutch master cylinder. If I messed up the install anywhere I'm not sure why it's only affecting 2 gears and why it would control the throttle butterfly .
If the transmission is slipping would the ecu catch that and close the butterfly?

 

[Ross]

The PCM doesn't have any clutch sensor... so that shouldn't have anything to do with your throttle issue.
The PCM does know when load is being applied to the engine.
I wish my LSJ would do torque by gear, and HP Tuners does have some gear info in it, but I think it is just for automatic transmission tuning, as I couldn't get it to work for my manual. It doesn't even know what gear I am in, except for reverse, it does know when to turn on the reverse lights.

 

[comegetjoe]

The PCM doesn't have any clutch sensor... so that shouldn't have anything to do with your throttle issue.
The PCM does know when load is being applied to the engine.
I wish my LSJ would do torque by gear, and HP Tuners does have some gear info in it, but I think it is just for automatic transmission tuning, as I couldn't get it to work for my manual. It doesn't even know what gear I am in, except for reverse, it does know when to turn on the reverse lights.

My 2009 ss/tc cobalt has the RPD and knew what gear I was in. Not sure exactly how it calculated it, but once I started moving, it showed up on the display.

 

[Ross]

Some of those aftermarket guages will use the speedometer & engine RPM, then can calculate the gear.
HP Tuners just wasn't changing gears in the log files, so the PCM wasn't recognizing the gears.
I wasn't able to make it do torque by gear for my manual transmission, but there is a whole section in HP Tuners for transmission tuning, so I think it is for automatic transmissions.
I could write a math function to calculate the gear, but if I can't adjust the engine torque by gear, then there is no gain for me.

 

[Desert Sasqwatch]

Gear is calculated from vehicle speed and engine RPM with the clutch engaged. It gets it right most of the time, but doing things like starting in 2nd gear can confuse it for a bit.