Fuel trim and running issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**jweb** · 10-23-2015, 09:34 PM

Just got my LS1 going and having some issues

Bank 1 STFT 10%
Bank1 LTFT 25%

Bank 2 STFT 0%
Bank 2 LTFT 5%

Seems to be running rich, fuel coming out the exhaust and really poor acceleration.

Any ideas?

If it helps I have a homemade intake, shorty headers, full exhaust and new O2 sensors.

BR3W CITY · 10-24-2015, 01:34 AM

Any codes being thrown? Do you have a log?

Bank one is essentially saying that "right now" your adding 10%, and "in general" you'll be adding 25%...which is a high commanded fuel trim.

The fact that the other bank is essentially perfect, says that it shouldn't be a global problem. My first inclination is to look for a major exhaust leak (false lean condition) causing it to dump extra fuel.

Those symptoms could also be indicative of a stuck or leaking injector (tho it would be more common to see negative fuel trims in that case)

Those AD's have room issues...where is your MAF located in that homemade intake?

And the #1 question I ask on virtually every post; who tuned it?

**jweb** · 10-24-2015, 11:58 AM

It had a lean bank 1 code. Thought I fixed it when I found a plugged injector.
No log my scanner doesn't save anything.

Attached a picture of my intake setup, MAF should be far enough away from the throttle body and filter. Filter is just under brake booster

Mail order tune, I want to have it dyno tuned but it's $550 and want to make sure I have any issues sorted out so I don't pay twice.

**jweb** · 10-24-2015, 03:39 PM

Also just checked my fuel pressure and have 50-55 with key on and 70 while running. Is this OK?
Posted via Mobile Device

Fixed this problem with a new filter/regulator

Now I have high ltft on both sides.

**Hart_Rod** · 10-26-2015, 01:32 PM

Quote:

Originally Posted by jweb

Also just checked my fuel pressure and have 50-55 with key on and 70 while running. Is this OK?
Posted via Mobile Device

Fixed this problem with a new filter/regulator

Now I have high ltft on both sides.

Did you change your injectors or are they factory?

**jweb** · 10-26-2015, 03:13 PM

Quote:

Originally Posted by Hart_Rod

Did you change your injectors or are they factory?

They are stock, I have tried several things with no luck. I am now wondering if a small exhaust leak is enough to cause a problem
Posted via Mobile Device

**Hart_Rod** · 10-26-2015, 03:52 PM

Quote:

Originally Posted by jweb

They are stock, I have tried several things with no luck. I am now wondering if a small exhaust leak is enough to cause a problem
Posted via Mobile Device

Yes

aknovaman · 10-26-2015, 10:30 PM

I have buddy in portland. if you need help troubleshooting it as he has hpt tuners and is very capable of helping fix the issue. Pm me if you want his contact info. He tunes turbolsx cars and hemi cars.

10-24-2015, 01:34 AM	#2
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Fuel trim and running issues Any codes being thrown? Do you have a log? Bank one is essentially saying that "right now" your adding 10%, and "in general" you'll be adding 25%...which is a high commanded fuel trim. The fact that the other bank is essentially perfect, says that it shouldn't be a global problem. My first inclination is to look for a major exhaust leak (false lean condition) causing it to dump extra fuel. Those symptoms could also be indicative of a stuck or leaking injector (tho it would be more common to see negative fuel trims in that case) Those AD's have room issues...where is your MAF located in that homemade intake? And the #1 question I ask on virtually every post; who tuned it? __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

10-24-2015, 11:58 AM	#3
jweb Senior Member Join Date: Apr 2010 Location: Oregon Posts: 1,209	Re: Fuel trim and running issues It had a lean bank 1 code. Thought I fixed it when I found a plugged injector. No log my scanner doesn't save anything. Attached a picture of my intake setup, MAF should be far enough away from the throttle body and filter. Filter is just under brake booster Mail order tune, I want to have it dyno tuned but it's $550 and want to make sure I have any issues sorted out so I don't pay twice. Attached Images

10-24-2015, 03:39 PM	#4
jweb Senior Member Join Date: Apr 2010 Location: Oregon Posts: 1,209	Re: Fuel trim and running issues Also just checked my fuel pressure and have 50-55 with key on and 70 while running. Is this OK? Posted via Mobile Device Fixed this problem with a new filter/regulator Now I have high ltft on both sides. Last edited by jweb; 10-24-2015 at 07:07 PM.

10-26-2015, 10:30 PM	#8
aknovaman Registered User Join Date: Aug 2013 Location: Tecumseh Posts: 355	Re: Fuel trim and running issues I have buddy in portland. if you need help troubleshooting it as he has hpt tuners and is very capable of helping fix the issue. Pm me if you want his contact info. He tunes turbolsx cars and hemi cars. __________________ Current project 1959 Willys = GEZR TRUK Geezer is a Latin compound word made up of two roots. Gee meaning Urine Stain and Zer meaning your pants are open! FMCDH GBU and GBA http://www.youtube.com/user/aknovaman/videos

10-23-2015, 09:34 PM	#1
jweb Senior Member Join Date: Apr 2010 Location: Oregon Posts: 1,209	Fuel trim and running issues Just got my LS1 going and having some issues Bank 1 STFT 10% Bank1 LTFT 25% Bank 2 STFT 0% Bank 2 LTFT 5% Seems to be running rich, fuel coming out the exhaust and really poor acceleration. Any ideas? If it helps I have a homemade intake, shorty headers, full exhaust and new O2 sensors.



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