Truck surging in upper 3rd gear

[TJ2000]

My truck runs fine 1st to 2nd and 2nd to 3rd but 3rd to 4th after about 2200 RPM it starts to surge when 3/4 throttle to full. If i use normal driving its fine or if i ease into it to full throttle it works fine but all out racing nothing. It is pissing me off i cant figure out why. I just installed a bigger turbo and put a fire punk stage 3 valve body in my transmission. My scans will be attached and my tune. The jump 1 is a log of a few pulls, @1:43 you can see the 1 longer pull. Jump 2 is building boost at around 40 mph and launching and the smooth is 4th gear easing into it top to bottom. There are a few videos as well.

Any help would be greatly appreciated! Before i blow this MFING thing up haha.


Tune 4.3.hpt tune 4.3 jump 1.hpl tune 4.3 jump 2.hpl

[Turbo_Mike]

My truck runs fine 1st to 2nd and 2nd to 3rd but 3rd to 4th after about 2200 RPM it starts to surge when 3/4 throttle to full. If i use normal driving its fine or if i ease into it to full throttle it works fine but all out racing nothing. It is pissing me off i cant figure out why. I just installed a bigger turbo and put a fire punk stage 3 valve body in my transmission. My scans will be attached and my tune. The jump 1 is a log of a few pulls, @1:43 you can see the 1 longer pull. Jump 2 is building boost at around 40 mph and launching and the smooth is 4th gear easing into it top to bottom. There are a few videos as well.

Any help would be greatly appreciated! Before i blow this MFING thing up haha.


Tune 4.3.hpt tune 4.3 jump 1.hpl tune 4.3 jump 2.hpl

Step 1, stop logging so much crap lol.
We know the lift pump is on and the oil isn't low. We dont care about MPG this trip or where you are spending time at what load. You get the point. The less things you log, the more data points per second you will have.

That being said, the log doesn't really show any reason for it to surge, but from what I've seen typically, the first thing that's gonna make it surge is rail pressure. If the rail pressure is "hunting" it will surge. Try logging less stuff so you can actually see the rail pressure swing, or whatever else is causing it, and maybe it will shed some light on what's going on.

[TJ2000]

ok i will trim it down and pull another log later today when i get a chance

[B00STJUNKY]

Just based off og the videos, it almost seems like you're hitting a soft RPM limiter since output shaft speed hasn't caught up to the commanded shiftpoint setting to shift into 4th gear, and you're powering through the converter enough that your RPM delta from engine speed to input shaft speed is higher than it normally would be on a stock truck.

You may try one of 2 things to circumvent this issue.

1) You can increase your RPM limiters and fueling tables so that you get full fueling to something more along the lines of 3600 RPM. That way, even though your delta between engine speed and input shaft speed is still greater than a stock truck, you'll be able to rev out a little higher and help the output shaft speed catch up to the shiftpoint setting for overdrive before you run into your RPM limiter.

Or

2) You can keep the same RPM limiters that you currently have in place, and decrease the output shaft RPM setpoint for shifting into overdrive.

Again, this is just a hunch based off of the videos. I haven't looked at your logs, but this is what it appears to be to me.

[TJ2000]

ok i will check into those a little bit. I was doing some more research about it i think its my turbo over boosting. I just put a new one on, and it is throwing an over boost code i didnt notice it due to no check engine light but i checked for them with the scanner and it pulled it up. I tuned it back to stock and never crossed 30psi and it didnt show up re tuned it and after i hit 35 psi it tripped again and started doing it.

[B00STJUNKY]

ok i will check into those a little bit. I was doing some more research about it i think its my turbo over boosting. I just put a new one on, and it is throwing an over boost code i didnt notice it due to no check engine light but i checked for them with the scanner and it pulled it up. I tuned it back to stock and never crossed 30psi and it didnt show up re tuned it and after i hit 35 psi it tripped again and started doing it.

Ah, yes. That will do it. You'll need to change your Over Boost parameters in [Engine Diag] [Airflow], and possibly (likely) your Torque Limit in [Engine] [Diesel Quantity] [Main Injection Limits].

[TJ2000]

Ah, yes. That will do it. You'll need to change your Over Boost parameters in [Engine Diag] [Airflow], and possibly (likely) your Torque Limit in [Engine] [Diesel Quantity] [Main Injection Limits].

Ok and is it just the airflow limit table? I changed that one and the transit one i will give it a shot tomorrow.

I already hit the torque limit table thinking that was the issue.

[B00STJUNKY]

Ok and is it just the airflow limit table? I changed that one and the transit one i will give it a shot tomorrow.

I already hit the torque limit table thinking that was the issue.

No, not the Airflow Limit table. You need to follow the exact path I specified to alter the "Over Boost" parameters.

[Engine Diag] [Airflow], under that tab path, you'll find a set of "Over Boost" parameters that you'll need to alter.

[TJ2000]

No, not the Airflow Limit table. You need to follow the exact path I specified to alter the "Over Boost" parameters.

[Engine Diag] [Airflow], under that tab path, you'll find a set of "Over Boost" parameters that you'll need to alter.

Ok, I see i missed read that. I see where you are talking about will give it a shot here in a few making the changes now. Will post back up as soon as i find out how it works! Thank you.

[TJ2000]

so moving those up helped out a lot it is now doing it after 3k rpm to the 3400 shift but very light so i think just a few more minor changes and we should be ok

[B00STJUNKY]

If you just set the MAP value to max, and set the RPM up higher than you'll be revving to, then it will never check for overboost.

[TJ2000]

If you just set the MAP value to max, and set the RPM up higher than you'll be revving to, then it will never check for overboost.

ok i will move them up more then and see if it fixes it

[TJ2000]

If you just set the MAP value to max, and set the RPM up higher than you'll be revving to, then it will never check for overboost.

ok so i am no longer throwing the over boost code but it is still doing it over 3000. I will attach 2 small logs and the tune im running. I think i am hitting a limiter still somewhere. I am going to use my tune but drop my shift point down to stock and see if it continues.

Tune 4 over boost off 3.hpt
Tune 4 over boost off 3 2.hpl
Tune 4 over boost off 3 3.hpl

[B00STJUNKY]

You have some fuel limiters acting against you in the form of tables that you need to adjust the maximum amount of mm3 allowed at higher RPM in order to achieve a stable fuel rate. You also need to rethink the parameters that you're logging, as there are some that you really don't need to log (such as balancing rate - that's mostly something you would want to use if you suspected you had a bad injector), and there are other parameters that you really ought to be logging (Inj PW, for example and Master Fuel Correction Reason).

You should also look into adjusting more than just your Transient tables when there are options for High, Med-High, Med-Low, and Low Density tables. Those tables are just as important as Transient, if not more. They are your "Steady State" tables, and the table that gets selected for use depends on your air density. The transient tables are for just that, transient conditions.

From your log, it looks like a couple things could be happening:

1) As stated earlier, you need to go through your tables and make sure that you're setting your mm3 limits to what you want them to be. You're bouncing between >100 and <70 after 2500 RPM. Again, look at not only transient tables, but also the High, Med-High, Med-Low, Low Air Density tables in your various tables, then pay particularly close attention to all the imposed limits on fueling across the entire RPM range in the tables found in the Main Injection Limits tab.

2) One of the Fueling Limiters that could be in play is the limits based on Fuel Pressure deviation. You can see that your Actual Pressure drops below Desired Fuel Pressure at times, and that could be triggering the Low Fuel Pressure Limiter table. Of course, it's not necessarily a good idea to ignore the fact that you're dropping below commanded pressure. You may need to revise your Fuel Pressure Regulator (aka FCA) Base Duty Dycle table in order to keep actual pressure closer to commanded. But if revising that table doesn't result in maintaining pressure, you could have a weak CP3 pump, or your injectors are too big for the pump you are running. You could always decrease the amount of fuel you are commanding in the ranges where the CP3 isn't keeping up, that way you should eliminate the surging you're feeling while the limiter table comes into play, then after pressure recovers, it lets things ramp back up, only to run into a deviation in fuel pressure again after it has ramped up, thus acting again to pull commanded fuel back down again (that could be the surge you're feeling).

First thing I would do is revisit all your limiter tables, and make sure you're not getting limited by any of those. After revising all the limiters, do another pull and log Master Fuel Correction Reason, and if you run into surging again, that could give you a clue as to why.

[B00STJUNKY]

Also, where you have your "WOT Upshift Force" parameter set to 3400, your "WOT Upshift Error Hi" is set to 3125 which is lower than the Force setpoint. It should be around 50 RPM higher than your Force setpoint. And your "WOT Upshift Error Lo" parameter should be set to around 50 RPM lower than your Force setpoint.

So, your Force would be 3400, Error Low would be 3350, and Error High would be 3450. Kind of doubt that will solve your surging issue, as I suspect that is related to one (or both) of the things mentioned above, but just another thing to look at and correct.

[TJ2000]

Also, where you have your "WOT Upshift Force" parameter set to 3400, your "WOT Upshift Error Hi" is set to 3125 which is lower than the Force setpoint. It should be around 50 RPM higher than your Force setpoint. And your "WOT Upshift Error Lo" parameter should be set to around 50 RPM lower than your Force setpoint.

So, your Force would be 3400, Error Low would be 3350, and Error High would be 3450. Kind of doubt that will solve your surging issue, as I suspect that is related to one (or both) of the things mentioned above, but just another thing to look at and correct.

Ok, thank you for the input you have been a huge help and i'm learning more. I will work on this over the next few days. As soon as i get it done i will give it a shot and try it again.

[TJ2000]

so update im still working on my tune but i have had no luck getting rid of the surging. I have it going back to the trans shop that put my firepunk valve body in on monday so they can check all there stuff.

[B00STJUNKY]

so update im still working on my tune but i have had no luck getting rid of the surging. I have it going back to the trans shop that put my firepunk valve body in on monday so they can check all there stuff.

Post a log and tune file with where you're currently at.

[RandomEnthusiast]

Is there anyway you can check trans pressure? I've seen a similar issue on a th400 where pressure would drop and cause slip.

[TJ2000]

Post a log and tune file with where you're currently at.

Ok i will grab one tomorrow and post it when i get home from work. here is my current tune i Took it all the way back to stock and restarted stock shift points and everything. All i have done so far is drop post injection smooth fuel rail and bump up timing and quantity some. As well as the over boost issue i was having fix.

Tune 1.2.hpt