4WDrift

iTrader: (3)

long story sumd up fast is i got a used half bridgeport 13bt with a ap engineering pfc. When it starts it wants go into "limp mode" as in when i give it throttle off idle it will rev for half and second and cut fuel then rev then cut fuel so on so forth. i noticed my vta1 (narrow) is reading 4.99 volts constantly even when pressing the plunger in with my finger. going to look for a short in the wiring cause it said at 4.99 volts when it was un plugged but could this be the source of my limp mode?

arghx

iTrader: (3)

the PFC doesn't really have "limp mode" but clearly you aren't getting a signal on the full range TPS wire, probably due to your previous owner's wiring mistakes.

4WDrift

iTrader: (3)

just who i was hoping would respond^

ok so i was hasty to say that it stayed at a constant 4.99 volts. at idle postion it reads 4.2-4.4 volts when off idle it goes to 4.99 and it highlighted. does this sound like what could be causing this issue? i did some resistance checks on the wires but for pin 2g i got two wires both br/w from the tps's that read .7ohms and the rest are reading Kohms and all wires to pin 2f where kohms....strange. will do some more digging tomorrow just throw out ideas.

arghx

iTrader: (3)

if the TPS voltages are not in spec then the computer won't be able to properly calculate how much additional fuel to inject as the throttle opens. What are your VTA2 voltages?

You do have an s5 TPS right? This is an AP Engineering PFC in an s5 car?

4WDrift

iTrader: (3)

correct and correct. voltages on vta2 are around 2 at idle (alittle high) and 4.80 at wot. Also there is a **** just after art that i believe is fuel temp that i dont have that reads 4.99, and the omp is deleted reading .07 and o2 sensor is .01 but turned off i believe since there isnt one

arghx

iTrader: (3)

first test the resistance sweep on the TPS plungers using an analog multimeter.

4WDrift

iTrader: (3)

installed another set of tps sensors, I plugged them in and watched their voltages change across the range to make sure they were good, installed them and adjusted. turns out since i am running a half bridge and the idle is set at over 1200 the narrow range never gets used. Either way the car stopped doing its "limp mode" now its just getting my warm start injection taken car of. thanks for the help

4WDrift

iTrader: (3)

thought i would update this alittle bit. If your running a high idle around 1500 or so, i found you have to remove the spring for the narrow range tps adjustment screw to get it to read in spec. havent warmed the vechile up and readjusted but just throwing it out there

arghx

iTrader: (3)

yeah that's mostly an s5-specific issue. the FD TPS is like a 90s Honda TPS and is adjusted differently. The s4 TPS is narrow range only and just has one adjuster screw.

thewird

iTrader: (8)

The PFC does have some sort of limp mode. If the TPS goes out of spec, the car starts crackling in the exhaust (not sure exactly what its doing) and the check engine light flashes (on a rhd FD). I experienced this once when tuning a RHD FD where the TPS would go out of spec with more then 1/2 throttle or so. It seems like some sort of fuel and/or ignition cut but it feels and sounds weird and unhealthy.

thewird

4WDrift

iTrader: (3)

its a fuel cut, i could watch my wideband and see the fuel completely lean out to nothing, then come back, then nothing

arghx

iTrader: (3)

Well I would expect it to run like complete crap but I guess "limp mode" isn't the term I'd normally use for that. It would be interesting to unplug the TPS and take a log with the Datalogit to see what is happening.

4WDrift

iTrader: (3)

i will work on that once my datalogit comes in

dougiepants

ok so lets say you are having this issue on the S4? the motor idles but you can tell it is just getting to much fuel. the vta1 is at 4.99v and the vta2 works perfect from .6v-4.86v thru the sweep. Im curious how to sending a signal to the vta1 or how to fix this issue please...

Banzai-Racing

iTrader: (11)

Pretty simple, just follow the installation instructions. http://www.banzai-racing.com/S4_PFC_install.htm

-The short 8" unterminated wire marked FRT allows you to install a full range TPS (S5 or FD).
-If you are using the S4 TPS, splice the FRT wire to the 3F wire

Finally figure out that you adjust the TPS with the screw on the throttle?