Hello all, I believe I may have a somewhat serious problem that I can’t seem to find the fix for. I daily drive my rx8 and last Thursday after work it didn’t start, it started and drove normal when I went to work. It cranked but wouldn’t start. I called out the RAC and they identified the problem to be the crankshaft sensor (eccentric shaft sensor) so I had it towed back to my house after replaced the ESS. This however didn’t do anything. As mentioned in the title I still have the crankshaft sensor code as well as U1900. I have checked the wiring from the ESS and didn’t notice anything, checked the ground under the airbox which I have seen mentioned on other threads and although it may be flooded, it definitely isn’t the main problem here. I have also attached a video of me trying to start it if that helps and I know it doesn’t sound right. I am at a complete loss and thought I may find some help here. Any information is greatly appreciated.

 

Your rpm needle barely budges when you crank. It does a little blip and falla back to 0. So either the ECU isn't reading rpm from the ESS or the ECU is not alive at all. The fact that you're able to crank tells me it's alive and the immobilizer has allowed it to crank, so I would look for damage between ECU and ESS. If you connect an OBD data reader, does it show normal cranking rpm? Maybe the cluster is what's losing connection. Is the engine actually cranking (check visually).

 

I just went and checked and the OBD reader is a
saying about an average of 200 rpm cranking and going down to 150 for a second occasionally and the timing belt is moving so everything is trying to start but it won’t. I don’t really know where to start for checking all the wiring between the ECU and ESS. Also, is it normal when having trouble starting for the cranking to be cranking like it does. I mean how it cranks 4-5 times and then stops for a split second and does it over and over again?

 

So if the ECU is getting RPM signal your ESS is OK. The gauge cluster isn't connected to the ECU though. Loose plug maybe? That explains the U1900.

Next question.. are the spark plugs firing? Have the coils been changed recently?

 

I just replaced the ESS thinking that was the problem so that’s definitely fine now even though there is still a code for ESS for whatever reason. The last owner changed the coils and spark plugs at most 18 months ago so they should be fine. I’m thinking it has to be a wiring problem but I am not sure as well as I’ve got no clue how to sort that out.

 

It would be good to validate that the spark plugs are actually firing, with a light or spark tester. Have you tried deflooding it? Does the exhaust smell like fuel while you crank? Are the spark plugs wet? It might not have been flooded when this started, but it might be flooded after the attempts

 

I would assume it’s flooded and I tried deflooding it using the accelerator peddle way and nothing changed. I don’t believe that’s what stopping it from starting as the ECU is still reading a problem with the ESS. I haven’t checked whether the spark plugs are firing but I wouldn’t see why not and again I don’t believe that’s the main cause of concern. I can deflood it when it’s actually able to start.

 

Well the spark plugs would confirm that it's getting an rpm signal. Otherwise it wouldn't fire. Does the ESS code come back if you clear it?

If the OBD reads a consistent rpm signal, the ESS is working.

 

I have already cleared the code and it didn’t come straight back but it has come back after reading the car again earlier. The OBD does read a constant reading although it fluctuates quite a bit.