RangeRovers.net Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
Hey,

Just finished putting a fresher 3.9 with new cam, lifters, seals, and gaskets in. Got it running, pumping oil, pushing coolant around, etc. It will not restart when hot. My friend (Rover tech) and I have triple checked the timing. We've tested fuel delivery, injector pulse with noid lights, spark, each wire, etc.

We have found that it's over fueling on a hot restart and flooding. When we pull the tach input to the ECU wire off of the "-" terminal on the coil it will sputter then crank. If I touch that wire on and off of that negative terminal while cranking it will start then I can put the wire on the coil and leave it running. It'll be really rich then settle right into idle.

We have tested the ICV, idle is set right, timing is at 10degrees (here in Colorado that's a good setting).

I put a new MSD Blaster 2 coil in it today and that didn't make any difference. I'm using Rover wires and NGK copper plugs. I've also swapped O2 sensors, coolant temp sensor, fuel temp sensor, TPS switch (from engine that was pulled out of my rover that ran pretty well inspite of low compression).

Any thoughts as to how leaving that "-" from the coil to the ECU. This is the White wire that joins the MAF wires in the loom back to the ECU. Labled as going to 162 in the Rave Workshop manual schematic. It's labled as "Coil Negative(engine RPM input to ECU). I think it's flooding and by pulling this wire it's cranking and sparking without additional fuel so it clears out and sputters then by putting the wire on and off quickly as it cranks I'm giving it enough fuel to start but not too much to flood. Once running I can connect and it runs fine.

Thanks in advance. I've been searching all over for a solution to this issue.
 

·
Registered
Joined
·
330 Posts
Even though you swapped the fuel temp sensor, put a meter on it next time to be sure.
Also put a meter on both the MAF and the wire going to the ECU. There's a resistor in line (aka chicklet) and maybe that is acting up when hot.
 

·
Registered
1995-2002 Range Rover Classic
Joined
·
1,413 Posts
Even though you swapped the fuel temp sensor, put a meter on it next time to be sure.
Also put a meter on both the MAF and the wire going to the ECU. There's a resistor in line (aka chicklet) and maybe that is acting up when hot.
fuel temp sensor has nothing to do with flooding, it monitors fuel temp to avoid fuel evaporation this is on the fuel rail it self.

on the other hand, the ECT or electronic coolant sensor is located on the intake manifold, near the thermostat. this unit is what controls fuel feed, the o2 sensors control air...those two combined control fuel air ratio mix, the white wire on the MAF harness is what controls the fuel injector pulse rate, as the engine speed varies the injector pulse goes along. disconnecting it stops the injectors from firing thus clearing your flood.

same result if you hold the throttle wide open while cranking, the TPS has a built in dead spot where WOT stops the injector from firing so engine starts with the excess fuel in chambers during a flood, allows air to enter in order to complete combustion while the WIDE throttle clears the excess fuel. hence your excessive black smoke upon start up.
 

·
Registered
1970-1995 Range Rover Classic
Joined
·
372 Posts
fuel temp sensor has nothing to do with flooding, it monitors fuel temp to avoid fuel evaporation this is on the fuel rail it self.

on the other hand, the ECT or electronic coolant sensor is located on the intake manifold, near the thermostat. this unit is what controls fuel feed, the o2 sensors control air...those two combined control fuel air ratio mix, the white wire on the MAF harness is what controls the fuel injector pulse rate, as the engine speed varies the injector pulse goes along. disconnecting it stops the injectors from firing thus clearing your flood.

same result if you hold the throttle wide open while cranking, the TPS has a built in dead spot where WOT stops the injector from firing so engine starts with the excess fuel in chambers during a flood, allows air to enter in order to complete combustion while the WIDE throttle clears the excess fuel. hence your excessive black smoke upon start up.
I was actually going to chime in on this. I recently failed emissions due to a bad ECTs. I also had some hot start issues due to excessive gas. Plug gaps were worn, and engine was running close to normal otherwise. I didnt throw an ECT code until i change to properly gapped plugs.
 

·
Registered
Joined
·
330 Posts
FTS from WSM.... "The fuel temperature thermistor (sensor) is located in the fuel rail forward of the ram housing. The thermistor sends fuel temperature data to the E.C.U, the E.C.U on receiving the data will adjust the injector open time accordingly to produce good hot starting in high ambient temperatures." That is why I suggested.

Regarding the ECT... I always suspected that for hard cold starts more than hot restarts. Both are simple enough to check & rule out.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #8
Turns out I have finally figured it out and have concluded I'm a knucklehead. LOL

I had plugged the Injector #1 connector into the coolant temp sensor that is about 2" from that injector that uses the same connector. I did notice the plastic on the coolant sensor is more of a grime covered dirty which which is easily confused with the grime covered dirty gray the injector plugs are. LOL I should have labeled plugs better on disassembly.
 

·
Registered
Joined
·
374 Posts
At least you've got it now. You're not the first to do that as far as I know, and guess you'll not be the last as it's quite easy to do. Probably a British trade union joke in there somewhere!
 

·
Registered
Joined
·
7 Posts
Discussion Starter #10
LOL. We were joking about this yesterday on the trail. It's not like the Rover doesn't already use a ton of different type connectors. They just couldn't mix it up on this one.
 
1 - 10 of 10 Posts
Top