Update: I swapped the fuel relay under the hood and tried to start the LR3 today and it actually struggled and then caught and ran. For a few minutes it just poured out white smoke from both pipes. Not a sweet coolant smell.

eventually it subsided and the exhaust was normal. It idled steadily.

i eventually turned off the car and tried to restart it, and just like that it wouldn’t start. The same struggling, sputtering, and dying.

I changed all of the spark plugs, but that didn’t help. There are no engine codes at all, and everything is plugged in properly.

what in the world could be the problem? What to do next?

of course this happens when the snow and cold weather finally arrives.

 

With all that you've done, if you are sure all the vacuum lines are sound and connected, I'm wondering if you had a fuel delivery issue in the first place. The fact that you swapped fuel relays and it did run for a short while might point in that direction.

​​No codes is a head scratcher, but she ain't running.....

 

I cleaned the MAF today and tried to start it, and again it started with billowing smoke out of the exhaust for a few minutes, and then it subsided and idled totally fine. When it was all warmed up I turned it off and tried to start it again and it wouldn’t start, same symptoms of stifling to start, then catching and then stalling out.

thats twice now where it started cold and smoked for a while and then seem to run normally, only to not start again afterwards. No codes once again.

To recap: I replace the coolant temp sensor because there was a code for it, the truck was pulsing at idle, and there was a misfire in cylinder one.

It was after buttoning everything up that the no start began. The only thing I did was give the throttle body a bit of a wipe, moving the butterfly. Since then I have replaced the spark plugs, cleaned the throttle body properly, cleaned the MAF, and erased the adaptations.

 

Update:

I used the GAP tool to read some test values while I tried starting the LR3. I used fuel temp, throttle body, mass airflow, and the coolant temp.

all of the numbers fluctuated except the coolant temperature which stayed static at -1C. That’s strange because the engine was still warm from running for a half hour, so I figure that there is no chance that is a correct reading.

maybe the new sensor is not functioning? Could a dead coolant temperature sensor cause this problem?

 

As the sensor impacts air/fuel mixture, and your numbers are fluctuating erratically, the new sensor could be bad. It the new sensor OEM? As painful on the wallet as it sometimes is, I try and stick with OEM.

 

I am waiting for the replacement coolant temp sensor to arrive, but I am still concerned as there were no codes to indicate that the new sensor is faulty.

I read in another thread that perhaps I have flooded the engine? Is that a possibility?

Another owner with the same problem as I have said that his fix was a mechanic identifying a flooded engine and somehow the mechanic was able to put the engine in flood control mode or something and clear everything out.

Does that even sound reasonable? Could moving the butterfly in the throttle body have caused a flooded engine?

I’m at an absolute loss here as there are simply no engine codes to track down.

 

clear flood mode is just holding gas pedal to the floor as you crank engine. im pretty sure its the same on any OB2 vehicle. summit 5280 is correct. if your ECM thinks the coolant is o degrees and its really 50 degrees F it will over fuel it and it will have hard time starting. ambient air temp sensor will have same effect. basically with a dead cold engine all of these sensors should read close to the same. ambient air temp/intake air temp/coolant temp. if you unplug the coolant temp sensor does the value change? this is an easy way to see if its wiring or a sensor.

 

Update: so I finally gave in and took it into a mechanic. I told them that I had replaced the coolant temp sensor with two new ones at this point.

He said that he tested the installed sensor and it was toast. They checked the wiring harness and said it was good. I told them to go ahead and order another one and so they did, but get this, the sensor arrived and the mech decided to test it before installing it, and he said it was reading at -40! Said the sensor wasn’t working properly straight out of the box.

He suggested they get another sensor from the dealership and test/install that one. It was $100, so surprisingly cheap from LR, but it will take a week to arrive.

He said that essentially that the truck was just dumping fuel into the cylinders at all times thinking the engine was a frozen block the whole time it was running.

Makes sense, and matches what some of you guys were saying.

now I wait and see if this will get my truck back on the road. This has been the only thing that has laid up the LR3 for this long since I’ve owned it.

Thank you for all of your help so far.

 

So at long last I had a dealership coolant temp sensor installed and the LR3 starts and runs properly now.

who knew that three separate sensors could be faulty!

Thank you for everyone’s help in here, looks like it’s OEM for sensors from now on.

 

Thank you so much for this write up. I am wondering if you can advise me on replacing the sensor. I have not been able to find a good video on the steps. I want to replace it because of the error below. If I ever get it replaced, I will certainly remember your post if it has trouble starting. My truck surges on startup but goes away after 10 minutes or so. P0116-24 (36) Engine coolant temperature - circuit range/performance - General signal failure - signal stays high