Rx400H Engine "shake" Upon Start-Up

[cduluk]

Hey guys,

For the past few months or so, i've noticed what i'd describe as a rather violent "shake" every time the engine starts in my '08 Rx400h (when the car's at rest). If i am sitting with the ignition "ON" (in P or D) while in a parking lot or at a light, it's very obvious when the engine starts. I've always noticed a minor shake, but it's become increasingly more violent as time goes on. When the engine starts, i can feel the shake and the entire car will "rock". However while driving, i don't notice when the engine kicks in, at least no more than i did before. It's only when the car is at rest.

Any ideas as to what the issue could be? It's A 2008 with about 80k miles. I still have the extended warranty on it (up to 100k miles), so do you think this would be covered?

Thanks in advance for any input!

[RX400h]

Ours does that to some extent but I haven't felt that it's been getting any worse. I'd imagine that if a motor mount was loose, it would aggravate the intensity of the rocking but I doubt that is the case.

[maseace]

That's normal, mine does it too.

[MeryLexmas]

I think the engine mount comment it on the right track. You may have a broken one. In a non hybrid you can just put the car in gear with the hood popped and have someone brake torque it in reverse and drive. You will see the engine roll back and forth excessively if a mount it bad. Not sure how much you can brake torque a hybrid. Also bad or low octane gas can cause it. Most engine knock occurs on start up, so if the knock sensor hears knock, it's going to !Removed! timing which will make the start up less smooth.

[lenore]

Try the ISC reset....Mine smoothed out after doing it recently....

[cduluk]

Also bad or low octane gas can cause it.

Thankfully i've always used premium gas, either 91 or 93 depending on the station.

Try the ISC reset....Mine smoothed out after doing it recently....

That's a good idea lenore, i'll try that out this afternoon and see if it makes a difference.

[lemon]

What did you ever do about your leaky inverter? I doubt it's causing the shake, but you would (hopefully, if the technician know what he is doing) get the ISC reset done properly (via the diagnostic computer) when the new inverter was put in.

Are you due for new spark plugs, air filter? Make sure your tranny is not leaking where mine leaked (twice) - just look at my old posts for the pics..

[cduluk]

I tried the ISC reset procedure but it hasn't eliminated the shaking, unfortunately.

And lemon, i never showed the Dealer the inverter leak... I could tell the leak was definitely "old" and i know the response from the dealer would be to wipe it away and see if it reappears. I never wiped it clean but the leak isn't getting worse.

I might be due for spark plugs- i know they've never been done. And i've had the oil, oil filter, and air filter replaced twice a year (the last time being done in July).

Are the sparkplugs easy to get to on this engine? I'll take a look.

Thanks for the continued help guys!

EDIT: I should also note that i'm still having the "buzzing" noise when the A/C is on. Whenever i have the air conditioning button activated and set the inside temperature below 70, i get this "buzzsaw" noise coming from the engine compartment. It literally sounds like a buzzsaw. The sound continues until i set the A/C off. I've been so busy i haven't made it to the dealer. Could the noise be related to the engine shaking?

[lemon]

EDIT: I should also note that i'm still having the "buzzing" noise when the A/C is on. Whenever i have the air conditioning button activated and set the inside temperature below 70, i get this "buzzsaw" noise coming from the engine compartment. It literally sounds like a buzzsaw. The sound continues until i set the A/C off. I've been so busy i haven't made it to the dealer. Could the noise be related to the engine shaking?

If it wasn't a hybrid, a bad A/C compressor (bearing etc.) might contribute to engine shaking (or a faulty idle up switch that failed to increase engine idle speed when the compressor was running), however, in the 400h the compressor is electrical, powered by the traction battery. It would not cause engine vibration.

Mine was also making a buzzing noise, but only for the first few minutes upon startup. After a short run time, the noise was reduced (but not completely gone) The dealer (as expected) said it was normal, even though I mentioned that it never made the noise when I first got the vehicle.

[Swiftly]

I'd like to focus on the OP's statement...and the entire car will "rock".

I'm still getting used to this car. For the first time today I decided to leave the engine on while waiting in a parking lot for partner to finish up in a store; first snowfall, I needed heat, and wanted to keep windows clean. A minute later the car turned off but the heater was still running and I was listening to some tunes....all systems normal, Captain. Some time later the engine started with a coincidental lurching forward motion that was alarming enough to startle my reflexes to get my foot going for the brake with all due haste. In that split second I realized the car wasn't going to go anywhere, my heart skips a beat, and the foot goes back to the floor....whew, that wasn't a tractor beam, Scotty. The motion can be described like this...think about driving a manual tansmission and you pull into your driveway and stop the car, you turn off the key but you let out the clutch before the engine finishes turning completely and the car lurches forward a bit. OR it can also be described like this...think about driving an automatic transmission and you pull into your driveway and stop your car on a slight down hill, you put it in park and turn off the key, let off the brake and the car rolls forward until the play in the trani is taken up.

My wait in the parking lot was long enough for this to happen a few more times...(she never stops shopping when she promises!)...and this forward motion was repeated upon each startup. It does take some conscious will to keep your foot from heading for the brake pedal. So, how much lurching is normal? Is it just another idiosyncrasy I need to get used to?

Thanks for the replies.

[cduluk]

I'd like to focus on the OP's statement...and the entire car will "rock".

I'm still getting used to this car. For the first time today I decided to leave the engine on while waiting in a parking lot for partner to finish up in a store; first snowfall, I needed heat, and wanted to keep windows clean. A minute later the car turned off but the heater was still running and I was listening to some tunes....all systems normal, Captain. Some time later the engine started with a coincidental lurching forward motion that was alarming enough to startle my reflexes to get my foot going for the brake with all due haste. In that split second I realized the car wasn't going to go anywhere, my heart skips a beat, and the foot goes back to the floor....whew, that wasn't a tractor beam, Scotty. The motion can be described like this...think about driving a manual tansmission and you pull into your driveway and stop the car, you turn off the key but you let out the clutch before the engine finishes turning completely and the car lurches forward a bit. OR it can also be described like this...think about driving an automatic transmission and you pull into your driveway and stop your car on a slight down hill, you put it in park and turn off the key, let off the brake and the car rolls forward until the play in the trani is taken up.

My wait in the parking lot was long enough for this to happen a few more times...(she never stops shopping when she promises!)...and this forward motion was repeated upon each startup. It does take some conscious will to keep your foot from heading for the brake pedal. So, how much lurching is normal? Is it just another idiosyncrasy I need to get used to?

Thanks for the replies.

That's exactly how i'd describe my experiences, also. It's a violent "lurch", the same lurch you get when you put it into park before you're totally stopped. That "rocking" back and forth does not seem normal to me. It seems to do it more often when it's cold, that i do know. From standing outside of the car, you'd swear there was "something seriously wrong" with the car.

I'm thinking it's something to do with age. I seriously abuse my 400h (it's a workhorse for sure) but i'd like to be able to fix it.

[katzjamr]

I have had this issue with my 2006 400h that has 91,000K on the odo. I describe it more as a lurch or more rough startup that shakes the vehicle, but it is random and usually starts and stops smoothly at rest. At 60K my dealer wanted to clean the throttle body but since it was not warranty work, so i said no. At 90K it was clearly dirty in there and i had it done, it helped make the engine starts smoother when starting at rest. Your spark plugs should go well over 100K in the 400h and i dont think that is the source of the problem. still in love with this car seven plus years later.

[cduluk]

I have had this issue with my 2006 400h that has 91,000K on the odo. I describe it more as a lurch or more rough startup that shakes the vehicle, but it is random and usually starts and stops smoothly at rest. At 60K my dealer wanted to clean the throttle body but since it was not warranty work, so i said no. At 90K it was clearly dirty in there and i had it done, it helped make the engine starts smoother when starting at rest. Your spark plugs should go well over 100K in the 400h and i dont think that is the source of the problem. still in love with this car seven plus years later.

I have had this issue with my 2006 400h that has 91,000K on the odo. I describe it more as a lurch or more rough startup that shakes the vehicle, but it is random and usually starts and stops smoothly at rest. At 60K my dealer wanted to clean the throttle body but since it was not warranty work, so i said no. At 90K it was clearly dirty in there and i had it done, it helped make the engine starts smoother when starting at rest. Your spark plugs should go well over 100K in the 400h and i dont think that is the source of the problem. still in love with this car seven plus years later.

katzjamr,

My 400h is still under warranty (cpo) so do you think they'd clean the throttle body for free? I haven't shared the issue with my dealer, but i have a feeling they'd simply deem the shaking as "normal" and blow me off... And since it doesn't always shake, it'd be hard to duplicate the issue for them.

[katzjamr]

I waited until the tech showed it as an area of concern when they rate the condition of the components on the car on the lube oil filter report. My dealer has a green, yellow, red box that they check when they look everything over. You can ask your dealer about covering it however i think it is normal maintenance. They clean the fuel injectors and throttle body, it runs about $300 in seattle. My guess is that the randomness of the lurch on startup at rest is a result of the postion of the engine internally when it shuts off. My dealer says the new models do it as well

[katzjamr]

I waited until the tech showed it as an area of concern when they rate the condition of the components on the car on the lube oil filter report. My dealer has a green, yellow, red box that they check when they look everything over. You can ask your dealer about covering it however i think it is normal maintenance. They clean the fuel injectors and throttle body, it runs about $300 in seattle. My guess is that the randomness of the lurch on startup at rest is a result of the postion of the engine internally when it shuts off. My dealer says the new models do it as well

I also wanted to mention that i think this is partially a gas issue also. back in 2005 when the whole idea of this model was alot newer we were experimenting with regular gas, rather than premium in these vehicles. The regular fuel results in lower mpg, and a less responsive engine, however i remember the startups being noticeably smoother. I use premium because the engine was designed for it, i like the quickness, and the better mpg makes the price difference amost nil. do you always use the same brand of gas? If so you might consider three tanks (it takes 3 to notice a change )of another brand and see if that helps. Just a thought...