In the last several weeks, my LR3 is having trouble in lower gears. The engine revs higher, and the car doesn't have the typical power. At first, it was off and on, now more frequent. Then I then noticed that the AC also quits during this time, and I can tell when full power has resumed when I feel cool air again. It's been warmer the last few days--almost 90, and I think that is making it worse.

I wanted to see if there was a general cause I should be aware of before talking to the dealership.

 

The ECM can command the AC compressor to disengage if there's an unusually high load on the engine (WOT, etc) - probably an overheat as well. Are your temps normal? There an entirely different ignition map and protocol the vehicle will use if any component is overheating. A similar situation may occur if there's excessive knocking detected by the ECM, though I'm not sure it would impact the AC operation unless it retarded the timing to the point where it was no longer making any power and had to disengage it? This is all speculation, you'd need to talk to one of the engineers to know exactly what would happen in a specific / unique situation - but that's the basic concept. Those modes usually report "Reduced engine power" and chime on the info display, and sometimes throw CEL.

I'm guessing you probably have on the order of 20-30 codes stored in various modules. I'd get those read and report back to us! Keep in mind the basic OBDII rental units will only be able to pull data from the engine - you really need everything, as this could also be transmission related (or at least some sensor fault that reports to the TCM only).

 

Thanks for all the information--didn't know that about the different mode, and perfectly describes the situation. I haven't see any error messages in the dash, but I'm having it scanned today. I'll report back when I find out.

 

Failed knock sensors, or really (REALLY) bad fuel as well might also do it.

If it's not misfiring (not running rough but rather just a large loss of power) then that narrows things down considerably. Shouldn't be too difficult to figure out at all.

I also remember reading about just how many sensor failures the ECM is able to handle while still keeping the motor running - you can even unplug the MAF and it can use the MAP and other sensors combined with a base/conservative tune. No power, but still runs. Same with any VVT failures (cam position/angle sensors for example) - it can just disable VVT and lock them into a conservative value (and again, a baseline ignition tune) which would definitely kill your power.

All of those should generate stored codes - but again, most detailed faults are only readable with the more serious scanners/computers.

 

I only made it half-way to the shop before a white cloud emerged from under my hood. I immediately stopped, got a tow, and the shop later discovered a t-connect (or of sorts) had failed and disconnected the hose from the radiator. They said they got the hose to reconnect securely enough, but the radiator connector is now slightly broken and might require a new radiator if it fails to stay connected.

...it looks like you were right. I'm surprised I didn't get any warnings, dings or anything--not even the temperature gauge. I drove with this off-and-on for a few weeks, surely there would be some radiator light or something?

My wife was trailing me to the shop when this happened, and just before the white smoke she saw a puff of black smoke from underneath the car. The shop inspection didn't reveal any specific reason for that.

 

Sounds like it got beat up on pretty good - hate to say it..

Definitely the starting point when you're worried about the continuity or safety of your vehicle should be to check all the fluids - if the tee is the one I'm thinking it is, then coolant would release rather quickly.


When mine went, I actually smelled a slight hint of coolant and was concerned enough that I pulled over and pulled the engine cover, to see the cracked bleeder tee spewing coolant everywhere. I quick-fixed it where I was, and later replaced it with a brass tee from a local auto/hardware store that can't fail. Vehicle never lost significant coolant and temp was never impacted.

In your case, if what you say is true and it is an overheat, then that's kind of alarming. Like I said, it'll reduce power and change some ignition parameters but at the end of the day (I guess for safety reasons) it WILL let you run that engine into the ground till it's cooked.

No idea why the temp gauge didn't move. That should have indicated an overheat, chimed, reduced engine power / overheat message on LCD (I'm pretty sure) AND the coolant level sensor should have also chimed and gave you an LCD warning on message center for low coolant. Sounds like all of these failed?

Logic would tend to dictate (regarding vehicle diagnostics) that that's unlikely, so it MAY be something else that's to blame. Perhaps you were experiencing an unrelated issue when your bleeder tee finally let loose on the way to the mechanic. If you still have the original plastic one on there, it WILL fail.

Good luck - give me some more info and I can diag a little further if you'd like - though it sounds like it's now in the hands of the mechanic. Let me know what he's doing or wants to do.

 

Thanks for the feedback and suggestions.

The whole incident really has me puzzled. Unaware of the limited power mode, I was confident the transmission was going out (which was not fun to ponder).

I drove the Land Rover dealership crazy asking them to validate and double-check everything. Getting out of this situation under $300 just doesn't seem right. So far the original issue hasn't returned--full power and driving just fine.

I am concerned that something else was damaged and/or the sensors are bad, but until I discover what those are I'm left with divine intervention as the only rational explanation.

 

Had a few of those myself lately.... God is good.

 

Wait so they didn't touch ANYTHING electronic; computer codes, resets, plugs, sensors, etc?

There's like a 2% chance what you described in your OP had anything to do with a coolant hose lol.

Then again, I guess I wouldn't be complaining!

Like I said, if it starts doing anything funky, just let me know and I'll try to connect the dots. I'm sure there's a few dots just waiting to be "connected" with this one!

 

After a week of driving, it acted up again, back into low power mode. Took it back in and they discovered the pump was bad. They said this also explains why the temperature gauge was ineffective.