here it is in a nutshell, when im crusin down the road at a steady pace, the car will studder a little and the boost will kick up to 4 lbs and then come back down, the a/f meter goes awol and then it goes into limp mode, like today i normally have a 40 min ride to work my car went into limp mode like 7 time while on my way to work, its been fine for a couple weeks now and just started the other day. a month or 2 ago i had a question about my fuel pump since it went bad, i had the bosch 034 motorsports pump and it went bad in less then one year so i went with an alternitive, a walbro 255. does anyone have any suggestions of what might be causing this.


-second:
since i had the walbro pump my car has been running super rich when i try to boost, and it is so rich the the car chokes on the fuel and cant boost, i have stg 3 revo tune and 550 injectors, do they have to put in a different code for the walbro pump, i never had this problem until the walbro pump was installed, i cant pass inspection until i figure out why its doing this, also cause it is running so rich i am throwing a code for fuel on the o2 sensors, i am overdue for inspection, it was up in february, so much help is appreciated.

the first has nothing to do with the second, when cruise control is on the car runs normal a/f ratio 14.8 to 15.4 give or take a few

 

bump please some help

 

bumping agian i can't afford to take it in to get fixed and i was hoping i could get some help maybe someone has had this problem and can help but im out of options.

 

they dont have to tune for a bigger fuel pump really, but if it was tuned on a weak pump that wasnt up to the task and had spots in the RPM range that were limited by pump output, and then you put a big pump that can put out as much fuel as the FPR and injectors are willing to allow into the engine, that would cause you to run rich.

the first problem sorta sounds like a wastegate problem or something.

have you vag-com'd it yet? whats the timing and fuel trims look like? and what year engine is it? i assume your a/f gauge is wideband right?

 

2000 a4 1.8t i dnt know anyone around my area with a vag-com, what do u mean by the fuel trim. and yes it is a wide band (aem), last night was one of the worst, it kept jumping back and forth for lean to richand when i say rich my meter goes to 10.0, well if it could i think it would go lower, it only last for like 10-15 min but it is hell during that time, especially when im just trying to go, even lightly pressing the gas pedal it wants to boost and boost more and more while im not moving my foot and then BAMN it goes into limp mode, im coming from a bosch 034 motorsports pump to an inline walbro with the stock unit in the tank.

 

if you had a scan tool you could see the LTFT (Long Term Fuel Trim) it adjusts your A/F when your STFT(Short Term Fuel Trim) goes to far out of wack I don't know that much about tuning or turbo's but getting a higher cap fuel pump shouldn't make your PCM unable to adjust fuel pressure or injector pulse width any MIL?

 

2000's dont have wideband o2 sensors stock, so the ECU doesnt really make corrections to fuel injection based on the o2 readings nearly as much as a 2001+ would. its mostly just based on MAF readings. if the only thing you changed was a fuel pump (and your car was used to your old, weak, fuel pump) more fuel would mean running rich. if you can do some A/F Ratio logs you can tweak the fuel settings down a little with lemmiwinks, that is if you had vagcom.