Buckvr6

i have a 2000 Boxster base 2.7. This was a complete running vehicle with no issues before the swap. I recently completed a 3.4 swap from the same year Carrera. I used all sensors and MAF from the 2.7. The intake and throttle body are from the 996. I have not remapped the ECU.
The engine turns over great but won’t start. I’ve narrowed it down to a no fuel issue. So far I’ve replaced the fuel relay, ignition switch, crank position sensor with no results. If I pull the fuel relay and jump the terminals the fuel pump will run but the injectors won’t fire. If I spray starting fluid in the intake the engine will fire for a few seconds.
I would appreciate any input or advice.
Thanks

Schnell Gelb

Wow , you did this without ever Posting on Rennlist or Renntech ?
Did you test the fuel pressure ? If you don't have a gauge and live dangerously, just crank for a nanosecond with the Schrader valve removed.
A cheapo gauge may be a good investment in case the fuel pressure regulator is failing.
During the rebuild your fuel may have gelled and clogged the regulator or filter.
You probably need a Durametric or substitute. It is the best way to get the attention of experts(not me!) because they will need all sorts of data to help you.I just speculate based on my previous mistakes ! Hope it helps.

Buckvr6

Thanks for the reply. I have not tested the fuel pressure yet because the fuel pump and injectors don’t seem to be getting
a signal to run. The pump will run if I pull the relay and jump the terminals but the injection won’t fire. I’m getting spark. I’ve double and triple checked all wiring and grounds. I even added an extra heavy gauge ground wire from the block to the body. The fuel filter is also new.
I guess I’m going to have to break down and buy the Durametric.

Schnell Gelb

Or find an Indie with PIWIS. Unless there is a Fuse issue? I mention that because it seems the DME is not transmitting a signal ? Suggest you also research "Initialization" . When the battery has been disconnected for a long time there is a specific procedure to follow.

extanker

i would confirm that you are getting fuel to the injectors then using a noid look to see if they pulse at the injector connection. you could try to disconnect the maf and try to start ......i tend to think it maybe an ecm issue not recognizing the data from the engine......cps etc

Schnell Gelb

good plan. I found the Harbor Freight Noid light kit had the correct adapter for the Boxch injectors and is very inexpensive.It is easy to use and see from the driver's seat. Unrelated - You can use it to test the wiring for the Variocam solenoids also
https://www.harborfreight.com/11-pie...set-97959.html

Buckvr6

I wasn’t aware of the initializing after battery disconnect. I followed the procedure and I can now actually hear the fuel pump prime when I turn the key! However, still won’t start. Fuses are good. Tried to start it again by jumping at the fuel pump relay... still nothing... just cranks. Then I sprayed starting fluid in the intake again and it fired right up and died.
I going to see if anyone local can rent or loan me a noid kit and fuel pressure tester tomorrow.

Schnell Gelb

just remove the Schrader valve as previously mentioned - Careful !

Macster

With fuel pressure at the fuel rails the only thing between the fuel and the combustion chamber is the injector.

It reads like the injectors are not being triggered.

While extanker touched upon this in his post, it was possible you missed it.

The DME must receive a valid signal from the crankshaft position sensor (CPS) or it won't know where each cylinder is and it won't trigger a fuel injection pulse in this case.

So, be sure the CPS is connected.

Also, the CPS can be loose or possibly mounted too close to or too far from the flywheel tabs.

The CPS can also just be bad.

Be aware if you test the fuel pressure at the test port on the fuel rail the cap is not supposed to be reused.

Buckvr6

There is most definitely fuel in the fuel rails. I disconnected the supply line and fuel poured out of the rail. When I bypass the fuel relay with a jumper wire to make the pump run I can feel the fuel pumping thru the pressure regulator and return line. I stated in my original post I’ve already replaced the CPS. I don’t feel the CPS is the issue since it will start and run with starting fluid.
I agree the injectors are not being triggered. Just can’t figure out why. All sensors and wiring are from the original motor which had no issues. Basically only the long block, intake manifold, and throttle body are from the 996.
I don’t think I’m getting fuel pressure or injector signal during cranking.

Macster

Missed that you had replaced the CPS.

Fuse C2 (30) controls fuel injection, inginition, and oxygen sensor heaters.

There is a relay in the injection, ignition, and oxygen sensor circuits. The relay is in panel 2 which is located in the rear trunk. Relay 2 is the fuel injectors, ignition coils, oxygen sensor heaters.

That you state the engine runs with starter fluid strongly suggests the ignition is working. This then sort of lets the C2 fuse and the #2 relay off the hook.

Don't know which DME you have in the car: 7.2 or 5.2.2.

But based on my review of the wiring diagrams it makes no difference: With either DME there is no fuel pressure input to the DME.

There only input I can see that is fuel related is fuel status which is used to control the low fuel level warning light.

I find it hard to imagine a scenario in which the engine is allowed to crank, spark is triggered, but not injector pulses. This doesn't sound like a security module gone amuck.

The behavior does hint at a wiring problem with the injectors. However, I'm at a loss to explain how the wiring to 6 separate injectors could get screwed up. That would require some kind of failure that's for sure.

That's all I can come up with. No much I'm sure.

Schnell Gelb

Maybe check the connector in the harness where all 6 injector circuits feed together. In other words an assembly error or a damaged connector

Porschetech3

Check the wiring connectors for crank position sensor and cam position sensor on bank 1 near the AOS. They are color coded black and white, but I have seen them swapped a few times. The connectors are right next to each other and will plug up to the wrong sensor. I have seen one of the techs at the dealership do this and also a friend of mine on a DIY rebuild did this. It will not show a fault code and can only be seen with a oscilloscope of the sensors. The easiest thing to do is check the color code, the white connectors male and female are for the crank sensor.

Schnell Gelb

Amazing ! There is only 1 other M96 guy I know who would have thought of that ! Well done.

Porschetech3

Thanks for the compliment, I hope that it is indeed the issue with the OP's no start issue. It is one of those "simple, but ever so difficult" things to diagnose.