No_Pistons_13v

for starters,i have spent over a week searching and havn't found anything near whats goin on with my car.alright this is complicated.i owned a 87 s4 na and it got totaled,so i picked up what was suppossed to be a 87 shell but was an 88 shell.i swapped over my engine,trans,ecu,wireing harness,a ton of sesors and relays not found on the 88 model,my main fuse box and inside fuse box (under dash).during the swap,i removed all emission controls from the car and added on a 2.5ft racing beat header.the car wouldn't start at first,so i double checked my fuel pump (wich is new) added new spark plugs (NGK's) replaced my spark plug wires (NGK's) checked to make sure all 4 coil packs were fireing and still nothing.i checked the fuel injectors and they get power but no ground.out of curiosity i used a gas can with gas (93 octane always) and added a vacuum line from the intake into the gas can the car fired right up.my buddy used the light tester and a wire to ground out the fruel injectors by grounding the light tester realy fast and shorted out the system and the car fired right up.once the engien fired up it ran fine.but once i shut it off,it wouldn't fire back up without be grounded out again.all 4 injectors are new,double checked all the sensors and relays for the injectors and still nothing.i thought maybe my ECU was bad.but first,my brother decided to check all the wires comming from the ECU,so he pulled each wire apart in the wire harness and along with checking each wire,i would turn the key over to get proper signal.about half way through the wire harness once a wire was checked and i turned the key over,it fired right up without a problem and continued to run perfectly fine for about 2 months and then all of a sudden back to square one again.it i use a gas can or short out the injector using the light tester and wire it fires up.when u use a light tester on the injector plug,it doesn't have a ground signal (yes,even when the key is turned over).do u think it's my ECU or do u think theres a more simple solution?

p.s:i did double check my wire harness for broken wires and didn't find any

please any suggestions or ideas would be appreciated

jgrewe

iTrader: (1)

First, welcome.

Second, break things up a little with punctuation, spaces, caps etc. it was tough to read the big blob of letters.

It does sound like you ECU is suspect. The ECU is where the ground comes from to fire the injectors, they get 12V + when the ignition is on. Do you have the engine grounded to the chassis well? If you have a good ground strap and the wires all have continuity try to find an ECU to swap out. You may have some luck digging around on the forum here for stock ECU problems and how the act. I do stand alone aftermarket stuff only so I'm only partial help on the stock stuff.

Good luck.

No_Pistons_13v

ok so im a shadetree mechanic without all the fancy electronics...wich means that the ground was there but not enough to show up on the light tester....my problem didn't lie in a ground issue like i thought it did.my problem was a bad fuel pump that was pulsating instead of staying on.my fuel pump was pusling power.? it would work and stop work and stop,so when i would check it it would be working but not long enough to fire up the car....weird?anyways as said before,it was new so i warrantied it out......im guessing defective.but anyways,thanx alot guys....................