I have a 2003 Discovery 2. It will fire up just fine but almost immediately die out. I started by replacing the crank sensor. This did not fix the issue. Checked the fuel pressure and it is steady at ~50psi. Sprayed starter fluid into the intake and the vehicle will stay running as long as I supply fuel. I went with a new battery (the old one was weak to start), no change. Thought it might have been that the BCU and ECM got out of sync, so bought a nanocom evolution and performed a resync. Still a no go. Thought that the BCU might be fried. Swapped for a known good unit and synced to the ECM, no change, Then swapped out the under dash fuse panel thinking the IDM might be corroded. No change. Finally, swapped in a known good ECM/BCU pair. Still the same. I am really running out of ideas on this one.


Couple questions.


Does the 2003 have the immobilizer coil around the ignition switch? I took off the surround to check on it and there is only a plastic light holder where I would have expected to see the coil module.


Any other thoughts on what would cause this? It really behaves like the passive immobilization is engaged.


Also, the vehicle started and ran fine prior to this. Meaning, I did not just inherit a vehicle that didn't work from the beginning.


Thanks for any help you folks can give on this.


Tony

 

wow. that's a lot of troubleshooting.
i think. cps can stop spark or fuel or both. good guess there. did you double check to see that the new one was properly installed?
fire- check, it lights the starter fluid
fuel- maybe, i assume you took a few different readings at the rail
air- we know it had enough air to light starter fluid. ...but fuel mixture? i would think you'd get some codes if it were a mix issue (sensors/maf)?
have you cleaned throttle body?
i think your led will be on if you are immobilized. also passive i think pops up a 1668 or something like that

 

Double checked for codes. None present, but will have to check for pending codes that haven't tripped the MIL yet.


CPS is installed correctly. Thought "maybe the replacement one is bad" but the tach gauge works and the nanocom shows RPM just fine so I'm not leaning that way just yet.


To answer the question about the immobilizer coil... I took the circuit board out of the key to my other 2003 Disco (yes I know having two of these is really asking for trouble but everyone should have a spare vehicle for just such an occasion). Then I left the board in the house and went outside and started up that vehicle without the fob guts. It fired up and ran fine. This means to me that there is no immobilizer coil circuit on the 2003. Just on the earlier ones I guess. BTW, this is the known running setup I used to test the vehicle I'm having problems with. After testing, I put everything back into the truck it belongs to.

 

Did you maf swap between the two?

 

haven't swapped MAF yet. But wouldn't that prevent it from running on the starter fluid?


I'll give it a shot tomorrow anyway and see what happens.

 

BCU to ECU synchronization problem. Maybe the wire is messed up? a loose ground somewhere? Your on the right track. It's 100% synchronization problem.

 

The ecu is turning the injectors off. so it will continue to run on spray.

 

Thanks for the reply Chris. Any idea how I would check the wire on this? Since it is a comm protocol, just looking for voltage wont tell me if the signal is corrupted. I can say that swapping in the working ECM/BCU combo from my other D2 did not change anything with the troublesome one. They are synced together, but the vehicle would still shut down. Swap them back to my running one and it still fires up and runs.

 

Should set a code for the synchronization if that's the problem.

 

I know how you guys love it when old threads get brought back to life. But I thought I'd post the solution to this particular issue.

I finally broke down and towed it the two hours to the stealership to see what they thought. They were as stumped as I was for a couple of days then it fired up and ran like crap on its own. After looking things over the tech realized that he had left off a vac hose and it was drawing unmetered air into the engine. So he opened up a couple more lines and it began to run better.

Before you say it, there wasnt a rag in the intake or anything like that. According to the LR guys, the MAF (should have listened to Dusty above) was returning bad data to the ECM. The air leaks were able to correct the mix just enough to run. All of this with NO CODES thrown. They could not explain it, but ordered a new MAF sensor and after plugging it in the vehicle fires up and runs like a top. I drove it back rather than tow and had no issues with it at all. They said that since the battery was on its last legs that the lower voltage or higher charge rate from the Alt might have fried the original.

Crazy eh?

Hope this helps someone else out there who might be going through the same issue that I was.