Hello Everyone,

My problem of hard starting has escalated into engine Hydrolocking from how much fuel is leaking from the injectors into the cylinders.

I am really in need of some advice or ideas from the members as it is really getting frustrating now, I will highlight the events for your reference:

Hardware:

1. Start up problem was there since day one of engine rebuild, car had Bosch 1650 injectors put in with the rebuild, we suspected they were leaking.
2. Swapped the 1650 injectors to ID1700x (SET 1), the problem remained, we started investigated the Tune and ECU, no matter what adjustments we made to the ECU it would keep dumping fuel.
3. I used a borescope to look in through the intake manifold and visually saw injector 2 dripping fuel, I removed the injectors and had them tested at a shop which said they weren’t leaking.
4. Reinstalled the same set into the car and instead of only having 1 injector leaking I now have a hydrolocked car and inspected with the borescope to discover 4 cylinders filling up with fuel!
5. I unplugged the injector plugs and the injectors were still leaking so I canceled out electronics at this stage, I had the injectors tested at another shop and they were indeed leaking.
6. I once again removed the injectors and sourced another set of ID1700x (SET 2) which I could use to test my car, the injectors were not made for the 997 so I used my SET1 top sides and swapped them over to SET 2, I had the loaner injectors cleaned and tested to 3 Bar and only had 1 leaking, we cleaned the leaking one and tested again all flowed perfectly and no leaks.
7. Installed the new set into my car and guess what? I have 4 cylinders leaking again and fuel filling up in the cylinders.

Electronics:

1. On the stock ECU I would get 12V to power and 3.5V to ground; we spent around 10 days testing wires and removing any modifications we made to the harness, the only way to get ground to 0V on the stock ECU was by removing Fuse F3 on Row D which is terminal 30, we really believed it was an electrical issue as from the reading we made on injectors we understood that ground should be 0V as the injectors are triggered by ground.
   
2. I wanted to cancel out if it could be the stock ECU that has the issue, and decided to plug in the Syvecs, on the syvecs I was surprised to see that we are getting 12V to power and 0.05V to ground?! At this stage we decided to stick with the syvecs as the ground was nearly 0V and believed it has to be a hardware issue (At this point we tested SET 1 and sourced the loaner SET 2)

Notes:

1. Cylinders fill up with fuel but all I see with the borescope are fuel droplets collecting on the injector tips (Like a dribble)
2. Car has a 5 Bar FPR
3. Priming fuel pressure initially holds 4 bar for 10 seconds and drops gradually.
4. My car has had the same issue with 3 sets of injectors now!!

At this stage I am really open to any ideas no matter how silly or crazy they may be, as we are running out of ideas here lol.

Just to get the ball rolling I'll start with some questions:

1. Is it correct that we should be getting 0V at ground?
2. Why do I get 0V to ground when I remove the terminal 30 fuse?
3. Can the fuel rail somehow cause the injectors to leak? Say if it isn't aligned correctly somehow?
4. Can my 5 Bar FPR be too large for this set up?

 

tareq that sounds like a huge headache.. definitely shouldn't be any volts on the grounds, first step i would check the dme/ injector relays and see if volts change when you pull it our swap it. car cranks and runs? lastly have porsche tech check resistance from ecu to injector cylinder that your getting the leaks on. looks like injectors are just getting power from ecm two wires, power and ground. maybe clean check all grounds and power before throwing a new ecu at it. I can send you good engine performance wiring diagram from mitchell1 if you need just email me.

good luck.

 

Hydrolocking? I wouldn't start the car for fear of blowing head gaskets or worse, breaking a rod.

 

Hey Buddy,

Thanks for the advice, Before the hydrolock the car would crank and drive, Did not attempt to crank after the hydrolock, however I would remove fuel fuses and plugs and crank to remove hydrolock so I could monitor the leakage after any changes we made.

I just did some electric testing will post it in a separate post maybe you guys can have a look and let me know what you think.

I haven't cleaned the grounds but made sure they are connected properly and visually inspected them.

Would be great if you can forward me the diagrams, I PM'd you my email.

100%, Once we discovered it was hydrolocked we did not start it again. I have read of the potential damage.

 

Well I just stepped outside and swapped out my 5Bar FPR to a Proto 5Bar FPR my friend had lying around, the injectors still leak.

I did some electrical tests by testing voltage after removing some fuses, I used the engine mount bolt as the ground for the tests and tests were done to injector wires of cylinder 1 with the injector plugged in (P is for Power, G is for Ground):

All fuses plugged in:
Ignition On
P 12V G 12V
Ignition Off
P 0.2V G 0.2V

Terminal 30 Fuse unplugged:
Ignition On
P 12V G 12V
Ignition Off
P 0.2V G 0.2V

Terminal 30 and ignition coil/injectors unplugged:
Ignition On
P 0.12V G 0.12V
Ignition Off
P 0.12V G 0.12V

What do you guys think?

 

Hey T, speak to your tuner buddy.

 

So I think we finally might have found the problem.

We removed the injectors off the engine again (5th Time with the engine in the car) and took them to an injector testing shop. The last time we tested we want upto 3 Bar, this time I told them to test them upto 5 Bar as my car primes at 4.4Bar with the 5 Bar FPR installed.

We had 6 injectors leaking at 5 Bar, we tried it a few times and confirmed they leak at 5 Bar, Dried the injectors and retested at 3 Bar and no leaks.

So it could be that the ID1700X aren't able to hold 4.4Bar of pressure from the rail side as my car builds 4.4Bar on priming. I am thinking of installing an OEM 3.8Bar regulator tommorow and see if that solves this headache.

I'm baffled as to how so many people run a 5 Bar FPR and have not faced this issue previously...

Does anyone know if running a 3.8 FPR affects the performance of the car?

Note: Before taking the Injectors to be tested we installed the stock injectors on cylinders 1,2 and 3; the stock injectors did not leak, I am assuming because the stock injectors are longer the internals can withstand more rail side pressure? I may be wrong..

 

One thing I hate is dealing with finding gremlins or ghost issues...drives me crazy!!


I am glad that you are finally getting to the bottom of this issue!