I need a little help. I have a 2007 mini cooper s. I just completed a rebuild of the engine and the fuel injectors are apparently not firing. I am getting fuel to the HPFP at 70psi. The HPFP is new and I tested it on another mini of mine so I know it is working. I verified that I am getting pressure to the rail. I am also getting spark at the plugs. It will crank but not start. If I spray a little starting fluid into the intake it will fire up, but then die when I stop. How do I go about checking the signal to my fuel injectors? They are OEM brand new replacements. There doesn't seem to be a relay or fuse since the signal and power come from the ECU. What should my next steps be? Is there anything that could be telling the car not to fire them? I do not see any abrasions in the wire harness and yes it is all connected properly. I do not own an oscilloscope. I have every other damn tool but never learned to use that or purchased one. Any help would be appreciated.

 

Have you found out the solution?

 

 

Popcorn :P

 

I have! This reply might be lengthy but hopefully it will help others in my same situation.

The main problem was a fresh rebuild that was not wanting to start. New pistons, rings, connecting rods, bearings, gaskets, seals, all sensors, valves and everything in between.

I checked for spark the old fashioned way by grounding a plug to the block, using a spark tester, and checking for constant 12v and signal with a test light and multimeter. Ialso checked all fuses and relays with a relay tester. Then checked the relay receptacles. So I know I had spark. I even tested it all with another new set of plugs. All of this rules out the ECM/DME as being an issue as far as spark is concerned.

I checked the low pressure fuel pump (at the pump) for power and ground. By doing that it rules out the JBE as being faulty. I then checked the pressure from the LPFP to the HPFP and it was at 70psi. So the LPFP was good.

The fuel rail pressure sensor was showing 250psi plus at the rail so I knew the HPFP was attempting to do it's job. When running it should be at 750psi at idle. If it was 100psi then that means the DME is attempting to put the car in limp mode, which it wasn't.

So far this all meant I was getting spark and fuel to the rail.

At this point I wasn't sure if fuel was making it past the injectors. So I sprayed some starting fluid into the intake through the driver's side PCV hose and it fired right up. Making me think that fuel was in fact not making it past the injectors.

I replaced the injectors with another set I had just to test, but the problem remained. I thought maybe they were not getting signal and wasn't sure how to test that. After calling a specialist I was told that that you can check with a multi meter or a test light. It's simple really, just two wires. You can choose the simplest of routes and connect your test light to a ground (not to a positive) then probe the two wires while starting. I did have signal.

Since I had signal to everything and it was all new and passed compression tests it made me feel lost. So I started going back through live data and noticed that my coolant temp read 220 something degrees even though the engine had not been ran.

THIS IS WHERE I GET TO SOUND LIKE A DAMN IDIOT. I thought my brand new temp sensor was bad so I bought another one and traded them out with the exact same results. I was about to set the car on fire or go crazy at this point. I decided to look at smooth one of my minis as an example and found out that I had plugged the temp sensor wire into the connection on the turbo inlet, and vise versa. Yes they are interchangeable, but it throws off the entire system without triggering a fault code. Since the car thought the motor was hot, it wasn't sending a much fuel as required to start a cold engine. That's it. I'm dumb. Hopefully my mistake might help someone else.

 

Nice sleuthing!