Rob2084

So I am trying to get my S5 to start. The car started before with no real issue and is now not starting after I have done some work to it. The engine is rebuildt by a professional (i.e 20 years exp). and has almost no runtime and when I did the sparkplug removal unflood the sounds from the compression sounded equal and puffed the same amount of gas out the plugholes. So compression should be good. Getting that out the way.

I removed UIM and checked the injectors. And what I found was that rear rotor injectors where both wet. And the front rotor only the primary injector was somewhat damp. The secondary was dry more or less straight through. I reseated everything thinking it might came loose as I was doing a clutch replacement and had the engine lifted some (don't have a carlift).

I put in brand new sparkplugs BUR9EQPs. And still she wouldn't even attempt to start. So many forumsearches later I did another deflooding, this time by removed EGI fuse, cranked for 20s, put the fuse back and turned the key. She sounded like she almost wanted but still didn't fire up.

So pulled the plugs yet again. This time I sort of got a clue what might be the issue but I am not sure. The front rotor plugs where completely dry. So my guess is that the injectors in the front aren't firing.

I've checked the Fuel Pump relay under the intake housing. Seems fine. The fuelpump starts when cranking and does build pressure (I heard it "slow down"). And there is fuel in the rails.

What I have still not tested is the injector plugs. But would it be likely that both primary and secondary not fire. Or will the secondary not fire during startup?

I heard clicking when I set the key to ON. I assume this is the main relay. I haven't done the continuity test yet.

I've checked all vaccumlines. Also measured the sparkplug wires. Seem to have the correct resistance.

Lastly replaced the oem pump as it was a coralreef inside the tank. So it's got a new tank and a DW300 pump (340l/h). I don't have FPR other than the stock one. I don't have the means of testing the pressure atm. Could the pump be to strong?

I haven't done or touched anything else in the enginebay. The car has been sitting with old gas. And was running on this before I attempted to start her again after the clutch job.
She has been started on starterfluid but didn't seem to have any rev or power. The oilpressure and temps were as expected after being warmed up. Wouldn't start if turned off on her own.
I know old gas can clogg injectors. But would this prevent the car from starting at all if the front rotor wouldn't get fuel?


I have Hayne Manual and have used the FSM for troubleshooting. But I can't seem to get anywhere now.



Any pointers where to continue would be appreiciated. Also I am not very well versed in acronyms yet. And sorry for the long post but I figure more info the better

diabolical1

iTrader: (3)

welcome to the board.

the first question i need to ask is what "work" did you do between the time the engine ran the last time and when it started it's current "no-start" condition?

1. check to see if your fuel lines were reversed

2. at this point you may as well dump the old stuff and get fresh fuel in the tank. make sure to check and/or change your filter if you have not already done so.

3. if there is doubt surrounding your injectors, then check the connectors, and then the injectors themselves.

Rob2084

Thank you!

I replaced the fuelpump and tank. The pump is now a Deatschworks DW300 (340lph). Fresh 98 in the tank. I also replaced the fuelfilter with a new OEM.

The other thing I've done is replace the clutch (inc. bearings etc).

1. I don't believe they are reversed. When the pump started first time it did do the pressure slowdown sound.
2. Fresh 98 is in the tank

3. I measured the injectors and they all had 17-18ohms
Also no leaks.

I have done some more troubleshooting and suspect there may be a grounding issue relating to the ECU. So I checked the wiring harness and it has been hacked up by the previous owner. There were tons of spots held together with tape. So ill have to go through it all.

I have 2 loose black wires that I cant seem to place. One is the grounding wire from the transmission bellhousing ( where its connected at one end) . And the other seems to come from the downpipe. But that is likely a sensor for eg. Not sure as I cant find the info on it in neither the FSM nor Haynes.

Hope this gives some clues.