Fuel Injection Question on a Range Rover - Stumped

[wobbiest]

I have been hunting down an issue with a 1997 Range Rover running very rich. I work on these trucks every day so this isnt the Rover cryptic box of fixing things. I tried a more than a few tests and concluded to just try a few of the peripheral swaps to see if there was any changed.

Had replaced:
o2
coil pack
plugs
wires
fuel temp sensor
coolant temp
cps
FPR
injectors
rail
MAF
TPS
IACV

Still running rich.

So tried a new ECU/BeCM combo. Nothing. Tried a new fuel pump and filter. Nothing. New Crank sensor. Nothing.

Then I found that if I unplug injectors 4 and 6 there is no change in idle or run condition. I can not hear them clicking either. However, the injectors are good ( I swapped 4/6 and 2/8 and 4/6 still arent firing). And they have good resistance. Also the leads are getting 12V as all of the injectors are getting. So there is no break in the wires. Just to double check, I peeled back the wiring and found no breaks.

So I have 12V going to all the injectors, the injectors are good and two different ECUs make for the same exact problem that 4 and 6 arent firing. I found some minor cracking on one wire on the camshaft sensor but the wire is intact and wasnt touching anything else. I have reset adaptions and I run Testbook on it. It throws no codes either.

I am lost. Any help would be appreciated.

[JeepsAndGuns]

Have you tried a compression check and cylinder leakdown test? There are times where the problem could be internal engine and not the FI system.

[EagleMark]

The 4-6 injectors not firing is causing the ECM to add fuel to others VIA fuel trims. What are your fuel trims doing in Scan tool?

The injectors should have power to them and the ECM grounds to fire them. So it could be a bad ground wire from ECM to engine. Also changing the ECM for same number ECM? Was ECM correct to begin with or was it maybe a four cylinder ECM and not have enough drivers for all injectors...

[wobbiest]

Have you tried a compression check and cylinder leakdown test? There are times where the problem could be internal engine and not the FI system.


New HGs and good compression. Also wouldnt explain only two injectors IMO.



The 4-6 injectors not firing is causing the ECM to add fuel to others VIA fuel trims. What are your fuel trims doing in Scan tool?

The injectors should have power to them and the ECM grounds to fire them. So it could be a bad ground wire from ECM to engine. Also changing the ECM for same number ECM? Was ECM correct to begin with or was it maybe a four cylinder ECM and not have enough drivers for all injectors...

I dont recall trims but O2s were rich. Rovers work on a 0-5V with 0 being rich and they are around 1V.
Hmm so if i check across the plugs they show 12v across the plug. Wouldnt that be a grounded circuit? I would think I wouldnt seee 12V across the plug with a bad groud? There are 8 leads with a ground that splices into a common ground into the ECU.
Swapped ECU and current are both OEM and correct.

thanks for your thoughts guys