07? GMC Sierra surging/hunting idle

[Timothy_james07]

I am not the tuner but trying to assist where I can and learn in the process.
Background on the build is 6.0. 80e swapped. Walbro in tank. Decapped injectors. 2-bar map. 78mm turbo. All the fuel related stuff was done while still running the maf and original map sensor before the turbo was installed. Ran and drove like factory. Did the turbo, map, and went full speed density and have been fighting the surge since then. The initial startup seems normal up until about 15-20 seconds and then is starts surging, even up until 1500-1700 rpm. Roughed in the ve table to within -5 to +5%. Followed the gen 4 idle tuning guide with no change. From the research I?ve done I believe it?s either something missed as far as failing the maf because it almost seems as though no matter what changes are made the problem persists or something with the VE table. New to all the gen 4 speed density stuff and know there are tons of people here that have endless amounts of knowledge on this stuff and hopefully someone can shed some insight. Will be posting the tune file as soon as I get it later this

Tune files posted.

[Ben Charles]

Be helpful to post tune and log…

[Timothy_james07]

I finally received the tune file but apparently don?t know how to post it. Can I email it to someone or someone tell me how to post it

[Shnraines]

Go to advanced tab by reply, then manage attachments

[Timothy_james07]

Got it, thanks!

[Timothy_james07]

Be helpful to post tune and log?

heres an idle log

[kevin87turbot]

You'd be better off using the 1/2 IFR, Double Stoich method in order to properly characterize the injector flow.

Did you change the Y axis on the VVE tables for 2 bar? Which 2 bar MAP sensor are you using? I don't recall seeing one with a Linear of 197 kPa.

Don't forget to increase the MAP Estimated Max to a number higher than the max boost level.

The VVE tables are pretty messy...especially at idle. That is likely the main source of the surge. You should use the smoothing feature to clean it up.

HP Tuners VVE table.jpg

[Timothy_james07]

You'd be better off using the 1/2 IFR, Double Stoich method in order to properly characterize the injector flow.

Did you change the Y axis on the VVE tables for 2 bar? Which 2 bar MAP sensor are you using? I don't recall seeing one with a Linear of 197 kPa.

Don't forget to increase the MAP Estimated Max to a number higher than the max boost level.

The VVE tables are pretty messy...especially at idle. That is likely the main source of the surge. You should use the smoothing feature to clean it up.

HP Tuners VVE table.jpg

So using that method would I return all the changes I made already back to stock? I’ll look for a write up
The map is an AS314
I’m not sure if the Y axis has been changed but I’ll check everything you listed!

[kevin87turbot]

You would have to do some more tweaking on the fuel tables if you use the recommended double Stoich method.

You would be a bit better off to convert it to the HP Tuners 2 bar OS. It will give you a more normal VE type table, as well as a Boost enrichment table. It also expands the range of the fan activation temps.

[blindsquirrel]

Standard AS314 crosses to Delphi PS10000, which is a 1-bar sensor (same part my truck used stock). That part's linear/offset is NOT 197.00/10.34. It should be 94.43/10.33. Although, I can't figure why you'd want a 1-bar sensor with a turbo.

[Timothy_james07]

Standard AS314 crosses to Delphi PS10000, which is a 1-bar sensor (same part my truck used stock). That part's linear/offset is NOT 197.00/10.34. It should be 94.43/10.33. Although, I can't figure why you'd want a 1-bar sensor with a turbo.

Summit showed it to be a GM 2 bar map good for 14.5psi

[Timothy_james07]

You would have to do some more tweaking on the fuel tables if you use the recommended double Stoich method.

You would be a bit better off to convert it to the HP Tuners 2 bar OS. It will give you a more normal VE type table, as well as a Boost enrichment table. It also expands the range of the fan activation temps.

Yea that sounds like something that needs to happen. Theres not much data with my injectors so I’m afraid the method you suggested may be difficult to set up.

[Timothy_james07]

After the 2 bar OS. If the tables are zero’d out how do I get all of the VE data for them?

Also since I didn’t have much data with the injectors can someone see if the data that is entered is good or if any of that needs to be changed?

[blindsquirrel]

14.5 PSI is the normal atmospheric pressure of the air you are breathing right now. The linear/offset for the sensor you have should be 94.43/10.33. Any airflow model changes you have made while it was using the wrong linear/offset will need to be un-done because it was based on incorrect MAP readings. This is not a matter of 'all opinions are equally valid', sorry.

A 2-bar MAP will read to 29 PSI. That's one BAR of normal atmosphere plus another BAR of boost.

[blindsquirrel]

12615136 is actually the Cobalt SS (supercharged) baro sensor, and it's linear/offset isn't 197/10.34 either. Not as far off as I was thinking, but still not right.

Tune files from cars that used that sensor don't have configurable linear/offset for the baro, only the MAP, which is a different part. Just search using that (GM) part number and the correct settings are here on the forum somewhere. It's a fairly common part.

[Timothy_james07]

12615136 is actually the Cobalt SS (supercharged) baro sensor, and it's linear/offset isn't 197/10.34 either. Not as far off as I was thinking, but still not right.

Tune files from cars that used that sensor don't have configurable linear/offset for the baro, only the MAP, which is a different part. Just search using that (GM) part number and the correct settings are here on the forum somewhere. It's a fairly common part.

Ok I’ll do some checking on that. Thanks for the info

[Timothy_james07]

idle scan.hpl


Switched over to the 2 bar OS, got the VE table worked out and the fuel trims within 5%. Idle surge definitely isn?t as bad. With the coolant up to 180-200 it may be around 75 rpm every once in awhile. Cold idle is still 3-400 but definitely better than what is was. New idle log attached if someone could check it out

[eXo3901]

Stop making changes until you input correct data for your injectors and MAP sensor.

Is this a stock cam and throttle body? If so, set everything in the Idle tabs back to stock.

MAP sensor: 200/8 (per quick search on here for AS314, but please search for more than 2 seconds like I did to confirm this.) Also, adjust the other MAP settings mentioned in this thread.

You need to correct your injector tables as mentioned above. Do you have a boost referenced fuel system or not? Post the part number of the injectors. They are decrapped so the best we can probably do is match the data to whatever factory application they came in.

Raise your HI spark table idle area 5 or 8 degrees and blend the surrounding areas. The idle spark needs a "window" to work in. The ceiling appears to be the HI table in this case. My assumption.

I only saw the VE table before you did the 2bar OS. But if still looks anything like that after the most recent changes you made then maybe consider setting at-least the idle area of the VE table back to stock, again assuming stock cam here.

Add dynamic airflow and injector pulse width to your logged channels.

[Timothy_james07]

Stop making changes until you input correct data for your injectors and MAP sensor.

Is this a stock cam and throttle body? If so, set everything in the Idle tabs back to stock.

MAP sensor: 200/8 (per quick search on here for AS314, but please search for more than 2 seconds like I did to confirm this.) Also, adjust the other MAP settings mentioned in this thread.

You need to correct your injector tables as mentioned above. Do you have a boost referenced fuel system or not? Post the part number of the injectors. They are decrapped so the best we can probably do is match the data to whatever factory application they came in.

Raise your HI spark table idle area 5 or 8 degrees and blend the surrounding areas. The idle spark needs a "window" to work in. The ceiling appears to be the HI table in this case. My assumption.

I only saw the VE table before you did the 2bar OS. But if still looks anything like that after the most recent changes you made then maybe consider setting at-least the idle area of the VE table back to stock, again assuming stock cam here.

Add dynamic airflow and injector pulse width to your logged channels.

The map should of been set to 200/8

Non return factory fuel system other than the walbro, stock TB
Cam is a 212/218 550/550 114lsa
Injectors are 25317628

[eXo3901]

Your flow rate table is set to one value, you only do that when you have a boost/manifold referenced fuel system. This table needs a factory style slope in your situation. Google says those are factory truck injectors. Do you have any information on the approximate flow rate when they are decapped?