07 LR3 seems to be braking while accelerating

[Rmeekdesign]

We just purchased a 2007 LR3 SE a few months ago. We’ve had a suspension fault message since the beginning, stemming from a bad ride height sensor that is in the process of being replaced, along with recalibration. This doesn’t cause us any issues except for lowering overnight, compressor raises it right up once it’s started up. We have had the control arms and all inspected, with no issues reported. The problem that is puzzling us, is that on occasion (0-2 times a week), we have loud bumping when turning sharp right into or out of the driveway/a parking spot. It happens very rarely. Today, after experiencing the bumping, it was followed by loud grinding sounds and the car essentially braking while I was trying to accelerate slowly. I waited and tried again, still happened, waited again and the car was fine. Any ideas on what to look at? Our indie shop couldn’t recreate it.

 

[Rmeekdesign]

Would like to add- no warning lights come on, we do not lose power, and brake pedal gets hard but is still able to stop.

 

[Houm_WA]

Here is what I think:

1. You have more wrong with your EAS than a bad sensor. Generally, if a sensor is bad or out of calibration you will get "cross-articulation faults" that put you down at a lowered height above 50 MPH. So the fact that it doesn't cause you any issues makes me think it's not a sensor, but probably a leak somewhere like a valve block.

2. I think you have a bad bushing, either in the lower control arms or the anti-sway bar.

3. Just sounds to me like you have HDC inadvertently engaged, resulting in the crunchy sound, stiff brake pedal and inability to recreate it (since you don't know what it is). You have to be going downhill for it to kick in, and off the throttle.

 

[Rmeekdesign]

Rear valve block rebuild is on my husband’s to do list, as we figured it could be part of the problem as well. The rear passenger side is lowering more than the driver side, with no leaks using soapy water test detected, thus leading him to diagnose as sensor. I should have included the rear valve block, as we are aware of it. We also notice that on occasion the lowering happens much faster while in the driveway, like a gasket is seating and unseating itself, creating a bigger leak. The sound and behavior from the car is just so jarring when it makes the grinding sound, and it no longer allows me to accelerate, but then goes away and operates normally for weeks at a time. Do you think the knocking and grinding could all be caused by the suspension issue? The bushings have been inspected by our mechanic, and we don’t have any bumping going over cobblestone or bumps. How would I be engaging the HDC? I’ll look around, as I’m sure that answer is easily found. Thank you!

 

[Rmeekdesign]

Looked into it and I don’t think I’m hitting the hdc button on accident, as I would have noticed the light on in the dash. We were considering it being a brake issue, but we’re still green and that’s just a shot in the dark.

 

[Rmeekdesign]

Now that I’m thinking about it, we usually have the HDC fault/ special programs unavailable message on startup. It isn’t putting that message up now, but earlier today when the grinding occurred, the message came up before it began working again. So, I think you’re right, the HDC is engaging (again, without the light on the dash), as what I’m reading about the HDC system when working properly is what this sounds like. So, some sensors need replacing maybe?

 

[Houm_WA]

I'd have to see it first-hand. I can only tell you what your symptoms describe. Swim upstream all you want; I've had an LR3 for 13 years and have been reading message boards for 12 of those. I've seen it all.

You had HDC on, you have a worn bushing, and you have a leak somewhere in your EAS.

 

[Rmeekdesign]

I have no desire to swim upstream, trust me. And I appreciate your knowledge, and trust it from those of you who have owned these cars as long, we love ours and hope to see 13 years with it! We tested it out this evening, the grinding is definitely an HDC sound. Thing is, my husband drove it down the street, made sure it HDC was off, and it kicked in on its own (flat surface). Once the fault came up and shut down HDC and special programs, the grinding stopped. What could be the cause of it kicking on by itself with no dash light showing? All suspension issues will be worked on this weekend, including the valve block. We are going to take it to the other indie shop to have them look over the bushings for a second opinion.

Thank you again, I would have never guessed the HDC, granted I didn’t know much about it before having this car.

 

[Houm_WA]

Well the traction control has a similar feel to HDC but it's momentary and there is a dash indicator.

Go drive down a hill with HDC on and let it kick in.... While it's engaged, step on the throttle, step on the brake...see if it matches what you are experiencing.

 

[Rmeekdesign]

Unfortunately, we’re in Florida! No hills! I’m hoping the mechanic can get it to do it, and has enough experience to tell which it is. You’ve been such a help, these boards are amazing, and a big reason why we purchased the vehicle.