i have a s4 n/a, stock everything except header/exhaust.

it will start (every time), idle smoothly. when in load, no power to be found. no load it sound like a two-step is coming on immediatly. in load, trying to drive it will go, slowly and try to step on the gas it falls on its face badly, almost dies(i think it would die if not rolling already). checked timing, no vac leaks, fuel pump works(key switch wired). when pulled the plugs they were very black from the rich fuel
the only thing i have not checked was comprssion.

all of this started after a bad main relay. when it went out my tach was jumping from 500 to 1.5k+ and poping and backfiring badly

just needing some help! thanks

 

How did you conclude that the Main relay was problematic?

 

connected a good/working one and when i turned the key the tach flickered and it started.

i could never get power coming out of the relay, only going into the relay


what else to look for? engine ran fine/good untill then(when relay went bad)

 

Lets say the replacement relay might still be the problem for whatever reason. To bypass it, which is very easy, just disconnect the 4 wire plug to it and jumper B/G to B/Y and W/L to B/W and see if their is a rats worth of difference.

 

main relay still working good. still have rich issues. swaped out AFM, main coil, plugs...
swapped fuel pump and it ran great once, spun in 1st, still going in sec, after that pull it started acting up again. one time when i was checking timing i left the jumper wire in and it ran better than after i pulled it out? any sugestion?

 

BUMP? i need help

 

test the range on the tps

, or you may be able to start and run without it? i cant remember.

if there's nothing wrong with the tps, or the car runs the same with it plugged in, do a fuel pressure test. just to eliminate it.

 

I know it sounds stupid but make sure you have L1/T1 going to the plugs on the front of the motor and L2/T2 going to the plugs on the back of the motor. I had the same symptoms and that is what it turned out to be.

Ron

 

This happened all sudden. only thing changed at first was the mainrelay

 

Wasn't sure when in the process you had pulled the plugs.

Ron

 

Disconnect the vacuum hose from the Pressure sensor, cap the disconnected hose, disconnect the TPS and take the car for a drive to see if there is any difference.

 

when doing so, what should i notice?