Front Bank STFT Maxed out Rich-Suggestions

**NOMIEZVR4** · 07-24-2013, 07:05 PM

Stock Injectors, Walbro 255 Hotwired Flash ECU

EVOscan is showing front bank is running lean as the Short Term Fuel Trim is +12.5 maxed out. The car has NO boost leaks. New Fuel Filter. Brand new Denso Oxygen Sensor as well on the front bank. o2 Activity is normal as the sensor voltages are fluctuating as they should. New Spark Plug Wires(NGK) and Spark Plugs (NGK Copper R5811a). Car occasionally throws a p0300 I believe because of the Short Trim being maxed out. I would really like to resolve this issue before throwing the big injectors back in. I am aware that it could be a partially faulty injector that could be causing this but just want to make sure I rule out all other possibilities before swapping parts and tunes.

Just for reference, Mid is +5
On the rear bank, Short is +2 and Mid is +6
All help appreciated.

**NOMIEZVR4** · 07-24-2013, 08:04 PM

Im running chrome v2 BTW..

**striker2** · 07-24-2013, 10:13 PM

check to make sure you dont have a cracked exhaust manifold. although for what its worth mine was maxed the same way, no leaks, no cracked manifold, good O2 sensors. I was able to bring it back down to under +5 on the front and -5 on the rear by adjusting the VE table in chrome.

**NOMIEZVR4** · 07-24-2013, 10:35 PM

I re-enforce welded the front manifold when the motor was out...

SO relieved to know I'm not the only one...Thank You for chiming in. Anyone else?

**RealMcCoy** · 07-24-2013, 10:39 PM

+12.5% is not even close to being maxed out. It's barely above what would be considered 'normal'. Is this at idle?

A 14% variation from front to rear would have me looking for the issue though. Do they come closer together with higher load?

**Greg E** · 07-25-2013, 07:17 AM

Originally Posted by RealMcCoy

+12.5% is not even close to being maxed out. It's barely above what would be considered 'normal'. Is this at idle?

A 14% variation from front to rear would have me looking for the issue though. Do they come closer together with higher load?

12.5% is maxed.

**NOMIEZVR4** · 07-24-2013, 10:52 PM

Correct me if I'm wrong but I believe 12.5 is the MAX value that will be displayed although it could be way more than what the number is showing. I'm sure you know this, but the target value is +/- 5% on the trims. Yes, the Short Trim refers to idle. The MID trims are fairly close at 5 and 6 percent respectively.

Maybe you might be referring to the older ECU's which may have a different range displayed, the trims im referring to are in regards to the 99 ECU.

**Greg E** · 07-25-2013, 07:20 AM

Originally Posted by NOMIEZVR4

Correct me if I'm wrong but I believe 12.5 is the MAX value that will be displayed although it could be way more than what the number is showing. I'm sure you know this, but the target value is +/- 5% on the trims. Yes, the Short Trim refers to idle. The MID trims are fairly close at 5 and 6 percent respectively.

Maybe you might be referring to the older ECU's which may have a different range displayed, the trims im referring to are in regards to the 99 ECU.

Anything under 100hz is the low trim. Usually that's idle.

Few questions:

Do you have periphery 0 bit 2 disabled?
Does the front sensor cycle while cruising?
Hotwired fuel pump with the stock FPR?

**RealMcCoy** · 07-25-2013, 10:15 AM

Originally Posted by Greg E

12.5% is maxed.

I don't have a 98-98 here in front of me to check, but I would expect that to be true for any of the LTFT's. I would also expect STFT to have much more resolution.

Originally Posted by Greg E

Anything under 100hz is the short term trim. Usually that's idle.

I keep seeing STFT being confused with LTFT low in this thread...