Surging Idle Problems

askiles

askiles

Goblin Guru
Update:

So the shop it is at now had some time to log it this morning, and they are saying that it sounds like there may be an air leak somewhere. I am not really sure where it would be. I checked all of the vacuum ports. They are all good. It could really only be at the supercharger gasket or somewhere on the intake manifold. That would be strange though, it runs well off idle. I suppose we will see!
 
DCMoney

DCMoney

Goblin Guru
askiles said:
Update:

So the shop it is at now had some time to log it this morning, and they are saying that it sounds like there may be an air leak somewhere. I am not really sure where it would be. I checked all of the vacuum ports. They are all good. It could really only be at the supercharger gasket or somewhere on the intake manifold. That would be strange though, it runs well off idle. I suppose we will see!
Click to expand...
Id try spraying carb cleaner (or similar) around the engine to see if the idle rises, use the straw to be a little more accurate of where you're spraying to narrow down the potential leak if you get a change in idle. Id start around the intake.
 
askiles

askiles

Goblin Guru
DCMoney said:
Id try spraying carb cleaner (or similar) around the engine to see if the idle rises, use the straw to be a little more accurate of where you're spraying to narrow down the potential leak if you get a change in idle. Id start around the intake.
Click to expand...
I actually did that, and didn’t notice anything. Then again, the engine was already surging in RPM so it may be hard to notice any change in RPM. Lol.
 
askiles

askiles

Goblin Guru
Update:

I swapped out the intake manifold and supercharger gaskets today, still exact same issue. The local shop who looked at it said the STFT’s at idle were wonky, making them think it was a leak in the intake somewhere. I think I have ran down all possible locations that there could be a leak. The only one that I didn’t replace was the fuel injector insulator cup things between the injectors and the heads, but I inspected those today and they seem just fine. All still in place snug, so I assume the o-rings on them are still intact.

I did have one question...on the fuel pump hat we have a send a return line that goes to the fuel filter. If I had those backwards, could this be a possible issue?? I assume I would have a car that didn’t run at all, but I am not exactly sure how the return works within the filter. I don’t think I have intermittent fuel pressure issues, but I don’t think there is any way to tell.

Any other suggestions guys?? I now have an MPVi2 so I can log stuff and tweak my tune if I decide to go that route.
 
George

George

Goblin Guru
In HP tuners look at idle then airflow; ETC area Scalar mine is currently set at 2,950.0000. This was the change that made the most difference in idle surge. To change the mixture at idle and lower RPM you will adjust MAF airflow vs Output Frequency.

Brad
816-605-3833 till 9pm central time
 
ctuinstra

ctuinstra

Goblin Guru
askiles said:
Update:

I swapped out the intake manifold and supercharger gaskets today, still exact same issue. The local shop who looked at it said the STFT’s at idle were wonky, making them think it was a leak in the intake somewhere. I think I have ran down all possible locations that there could be a leak. The only one that I didn’t replace was the fuel injector insulator cup things between the injectors and the heads, but I inspected those today and they seem just fine. All still in place snug, so I assume the o-rings on them are still intact.

I did have one question...on the fuel pump hat we have a send a return line that goes to the fuel filter. If I had those backwards, could this be a possible issue?? I assume I would have a car that didn’t run at all, but I am not exactly sure how the return works within the filter. I don’t think I have intermittent fuel pressure issues, but I don’t think there is any way to tell.

Any other suggestions guys?? I now have an MPVi2 so I can log stuff and tweak my tune if I decide to go that route.
Click to expand...
If you are asking if you could have the lines on fuel filter backwards from the fuel pump, I'm not sure how you could because they are two different sizes and will not interchange unless you cut the lines and put on new fittings and got those mixed up. Even if you did, I don't think it will cause an issue because my understanding is that fuel goes in the large port and anything that is not used by the engine will freely flow out the smaller port and return to the tank. The pressure regulator is in the pump on the return line not in the fuel filter.

Read your file and send it to me (read the entire contents and make sure to save it as a backup on your computer). I would just like to take a look at it. Maybe try a stock SS/SC tune just to see if that helps to rule out the tune.

I will PM you my email.
 
askiles

askiles

Goblin Guru
George said:
In HP tuners look at idle then airflow; ETC area Scalar mine is currently set at 2,950.0000. This was the change that made the most difference in idle surge. To change the mixture at idle and lower RPM you will adjust MAF airflow vs Output Frequency.

Brad
816-605-3833 till 9pm central time
Click to expand...
I will take a look at that, thanks! At this point I am nearly positive it’s in the tune. My tuner at Intense is willing to work on it too. I’ll just have to send the tune back and forth a few times before we get it I’m sure.
 
askiles

askiles

Goblin Guru
ctuinstra said:
If you are asking if you could have the lines on fuel filter backwards from the fuel pump, I'm not sure how you could because they are two different sizes and will not interchange unless you cut the lines and put on new fittings and got those mixed up. Even if you did, I don't think it will cause an issue because my understanding is that fuel goes in the large port and anything that is not used by the engine will freely flow out the smaller port and return to the tank. The pressure regulator is in the pump on the return line not in the fuel filter.

Read your file and send it to me (read the entire contents and make sure to save it as a backup on your computer). I would just like to take a look at it. Maybe try a stock SS/SC tune just to see if that helps to rule out the tune.

I will PM you my email.
Click to expand...
I did cut the lines and now have HP fuel hose on there. So I could have swapped them. Pretty sure I didn’t, but thinking of everything.
 
askiles

askiles

Goblin Guru
George said:
In HP tuners look at idle then airflow; ETC area Scalar mine is currently set at 2,950.0000. This was the change that made the most difference in idle surge. To change the mixture at idle and lower RPM you will adjust MAF airflow vs Output Frequency.

Brad
816-605-3833 till 9pm central time
Click to expand...
Here is what my tuner said could possibly fix it:

My suggestion to better dial in fueling is to smooth the base IFR table to get rid of the odd dip that GM tuned into it, and change the Volts multiplier to 1.720 from the 1.644 (IIRC) that I had in it at first.

Now that ought to get your fueling closer, but may not correct the idle. The shop might have to fiddle with the ETC tables a bit to calm down the movement of the throttle plate to regulate the idle. Adjusting min/max values will act a bit like an idle screw on a carburetor – and can set a base idle that will keep it from overrunning so much.
 
askiles

askiles

Goblin Guru
George said:
In HP tuners look at idle then airflow; ETC area Scalar mine is currently set at 2,950.0000. This was the change that made the most difference in idle surge. To change the mixture at idle and lower RPM you will adjust MAF airflow vs Output Frequency.

Brad
816-605-3833 till 9pm central time
Click to expand...
My idle airflow ETC Area Scalar is set to 2,950.0000.
 
ctuinstra

ctuinstra

Goblin Guru
In looking at your tune file, I cannot for the life of me figure out what they heck they are doing here. This is the flow rate of the injectors. Typically this is mostly linear. I guess this is the "odd dip" he mentions that GM programmed in. I've never seen that before in any tune nor stock tune.


8926


For reference, this is a GM Stage 2 tune:


8927


Before I would go much farther, I would either put a stock tune back on for testing or smooth out that dip like he said.

They did not change the torque management. That just makes it hard to drive. Odd, there are some setting changes that are identical, down the the exact same value as mine from ZZP. Really weird settings. Check out this weird graph. This is Injector Offset vs. Battery Voltage vs. MAP, basically changing the injectors depending on the actual battery voltage. Under normal conditions, much of this would never be used (8V or 18V). But look at the weird split in the middle of the chart and then the big spike at 8V, what the heck is the purpose of that? Again, my ZZP tune has this exact same setting but none of the GM tunes do.


8928
 
askiles

askiles

Goblin Guru
ctuinstra said:
In looking at your tune file, I cannot for the life of me figure out what they heck they are doing here. This is the flow rate of the injectors. Typically this is mostly linear. I guess this is the "odd dip" he mentions that GM programmed in. I've never seen that before in any tune nor stock tune.


View attachment 8926

For reference, this is a GM Stage 2 tune:


View attachment 8927

Before I would go much farther, I would either put a stock tune back on for testing or smooth out that dip like he said.

They did not change the torque management. That just makes it hard to drive. Odd, there are some setting changes that are identical, down the the exact same value as mine from ZZP. Really weird settings. Check out this weird graph. This is Injector Offset vs. Battery Voltage vs. MAP, basically changing the injectors depending on the actual battery voltage. Under normal conditions, much of this would never be used (8V or 18V). But look at the weird split in the middle of the chart and then the big spike at 8V, what the heck is the purpose of that? Again, my ZZP tune has this exact same setting but none of the GM tunes do.


View attachment 8928
Click to expand...
ctuinstra said:
In looking at your tune file, I cannot for the life of me figure out what they heck they are doing here. This is the flow rate of the injectors. Typically this is mostly linear. I guess this is the "odd dip" he mentions that GM programmed in. I've never seen that before in any tune nor stock tune.


View attachment 8926

For reference, this is a GM Stage 2 tune:


View attachment 8927

Before I would go much farther, I would either put a stock tune back on for testing or smooth out that dip like he said.

They did not change the torque management. That just makes it hard to drive. Odd, there are some setting changes that are identical, down the the exact same value as mine from ZZP. Really weird settings. Check out this weird graph. This is Injector Offset vs. Battery Voltage vs. MAP, basically changing the injectors depending on the actual battery voltage. Under normal conditions, much of this would never be used (8V or 18V). But look at the weird split in the middle of the chart and then the big spike at 8V, what the heck is the purpose of that? Again, my ZZP tune has this exact same setting but none of the GM tunes do.


View attachment 8928
Click to expand...
Wow! That is super weird. I will have to throw a stock tune on and see what it does.
 
ctuinstra

ctuinstra

Goblin Guru
After doing some more digging, I did find a 2006 stock file that has that same bump in the injector flow table. So I guess that is a GM thing. Not sure how any injector would flow like that but my guess is that it's to correct something.
 
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