1995 Ls400- Lunges Or Lurches Forward.

[averona]

Even when car is warm, when put into gear, neutral to drive OR neutral to reverse,

The car lunges or lurches forward in almost a dramatic jerking movement.

Can this be made a little more gentile?

1995 LS400

[eatingupblacktop]

Wait for the car to warm up a bit more and the idle to drop.

[don corleone]

check your throttle cable. very common issues. if the throttle cable is forward a little then the car thinks you are pressing the gas pedal. hince the lurch and maybe even a thump! here is the procedure for a 90LS your may be different

transmission_servicing_at.pdf

[eatingupblacktop]

Yeah, averona, I totally misread that this happens even when the car is warm. What is it idling at when this happens?

[averona]

Yeah, averona, I totally misread that this happens even when the car is warm. What is it idling at when this happens?

hi, it lunges pretty hard even at lower rpms (500-1000). i usually let the rpm's go down before i put it into gear, just to let it "warm up." anyway, that's why it's so suspicious. any ideas?

[eatingupblacktop]

How is the fluid level/condition/age?

[averona]

check your throttle cable. very common issues. if the throttle cable is forward a little then the car thinks you are pressing the gas pedal. hince the lurch and maybe even a thump! here is the procedure for a 90LS your may be different

godfather, i here a thump when i start the car as well. when it ignites, it sounds like a kick from inside. could that be the throttle cable too?

[nc211]

check your throttle cable. very common issues. if the throttle cable is forward a little then the car thinks you are pressing the gas pedal. hince the lurch and maybe even a thump! here is the procedure for a 90LS your may be different

godfather, i here a thump when i start the car as well. when it ignites, it sounds like a kick from inside. could that be the throttle cable too?

Nope, that's not the throttle cable, that's your driver's side motor mount, guaranteed. It's a low sounding, thump/kick right when the engine engages isn't it. Your mounts are simply worn out. You have three of them that probably all need to be replaced. Two for the engine that are circular "like a bagel", and the transmission mount "also referred to as the rear engine mount" I suggest you buy them online from a place like www.parts.com or any of the others. The transmission mount "rear mount" is around $30-$50" bucks, and you can do it yourself, as it's quite easy "do a search for the proceedures". I would then take the two motor mounts down to your local shop and ask them to install them for you for a $100 bucks. Unless you're quite handy, I wouldn't attempt the motor mounts yourself, as the driver's side is a real pain to get at. Once you do this, I promise you you'll notice an amazing difference to the car in general, specifically to your original question. The lurching won't go away completely, as it's just part of a 14 year old car now, but the new mounts will tighten everything up, and will also make a quiet car, even quieter by a mile!

I had the exact same thing on my 95, and the mounts fixed it.

The throttle cable adjustment can be felt the most when shifting gears with the a/c on. After the car has warmed up, put on the a/c and go for a gentle drive around the neighborhood. Do you feel the car kick when shifting to 2nd and 3rd gear? If so, then it's an easy fix with a single turn of the little hex bolt tensioner on the throttle cable at the point on the engine where the cable meets the flywheel. Just back it off a single turn, and go for a drive. The guys are correct, if it's just a bit too tight, then it tricks the transmission computer into thinking you're asking for a more powerful shifting pattern, then you really are.

[averona]

the mechanic says it's the idle control valve that is causing the lurch forward and the thump sound when engine fires. does that sound good to you?

check your throttle cable. very common issues. if the throttle cable is forward a little then the car thinks you are pressing the gas pedal. hince the lurch and maybe even a thump! here is the procedure for a 90LS your may be different

godfather, i here a thump when i start the car as well. when it ignites, it sounds like a kick from inside. could that be the throttle cable too?

Nope, that's not the throttle cable, that's your driver's side motor mount, guaranteed. It's a low sounding, thump/kick right when the engine engages isn't it. Your mounts are simply worn out. You have three of them that probably all need to be replaced. Two for the engine that are circular "like a bagel", and the transmission mount "also referred to as the rear engine mount" I suggest you buy them online from a place like www.parts.com or any of the others. The transmission mount "rear mount" is around $30-$50" bucks, and you can do it yourself, as it's quite easy "do a search for the proceedures". I would then take the two motor mounts down to your local shop and ask them to install them for you for a $100 bucks. Unless you're quite handy, I wouldn't attempt the motor mounts yourself, as the driver's side is a real pain to get at. Once you do this, I promise you you'll notice an amazing difference to the car in general, specifically to your original question. The lurching won't go away completely, as it's just part of a 14 year old car now, but the new mounts will tighten everything up, and will also make a quiet car, even quieter by a mile!

I had the exact same thing on my 95, and the mounts fixed it.

The throttle cable adjustment can be felt the most when shifting gears with the a/c on. After the car has warmed up, put on the a/c and go for a gentle drive around the neighborhood. Do you feel the car kick when shifting to 2nd and 3rd gear? If so, then it's an easy fix with a single turn of the little hex bolt tensioner on the throttle cable at the point on the engine where the cable meets the flywheel. Just back it off a single turn, and go for a drive. The guys are correct, if it's just a bit too tight, then it tricks the transmission computer into thinking you're asking for a more powerful shifting pattern, then you really are.

[averona]

the mechanic says it's the idle control valve that is causing the lurch forward and the thump sound when engine fires. does that sound good to you?

check your throttle cable. very common issues. if the throttle cable is forward a little then the car thinks you are pressing the gas pedal. hince the lurch and maybe even a thump! here is the procedure for a 90LS your may be different

godfather, i here a thump when i start the car as well. when it ignites, it sounds like a kick from inside. could that be the throttle cable too?

Nope, that's not the throttle cable, that's your driver's side motor mount, guaranteed. It's a low sounding, thump/kick right when the engine engages isn't it. Your mounts are simply worn out. You have three of them that probably all need to be replaced. Two for the engine that are circular "like a bagel", and the transmission mount "also referred to as the rear engine mount" I suggest you buy them online from a place like www.parts.com or any of the others. The transmission mount "rear mount" is around $30-$50" bucks, and you can do it yourself, as it's quite easy "do a search for the proceedures". I would then take the two motor mounts down to your local shop and ask them to install them for you for a $100 bucks. Unless you're quite handy, I wouldn't attempt the motor mounts yourself, as the driver's side is a real pain to get at. Once you do this, I promise you you'll notice an amazing difference to the car in general, specifically to your original question. The lurching won't go away completely, as it's just part of a 14 year old car now, but the new mounts will tighten everything up, and will also make a quiet car, even quieter by a mile!

I had the exact same thing on my 95, and the mounts fixed it.

The throttle cable adjustment can be felt the most when shifting gears with the a/c on. After the car has warmed up, put on the a/c and go for a gentle drive around the neighborhood. Do you feel the car kick when shifting to 2nd and 3rd gear? If so, then it's an easy fix with a single turn of the little hex bolt tensioner on the throttle cable at the point on the engine where the cable meets the flywheel. Just back it off a single turn, and go for a drive. The guys are correct, if it's just a bit too tight, then it tricks the transmission computer into thinking you're asking for a more powerful shifting pattern, then you really are.

[nc211]

Nope. Sounds like the wrong diagnosis, ESPECIALLY on the thump. Ask your mechanic how in the heck an idle control valve can "thump"? You have a bad, driver's side, engine mount. Whether if it "looks" ok or not, I know it's that mount. That is the mount that takes the weight of the torque of the engine when you accelerate. The engine wants to lean to the driver's side when it's under pressure. Simply put, after 14 years, it's leaned enough on that mount to permenatnly compress that rubber to create enough of a gap to cause the thump. I would simply buy the mounts online, and take them to a mechanic and ask him/her to install them for you. Otherwise, you run the risk of getting exactly what you just got, which is a mechanic with a lexus in his garage with a bad engine mount "typical repair on all cars" with the idea that he'll make some money off of you. Replace the mounts before spending anything on the car.

Furthermore, I would make damn sure he doesn't mess with that idle control valve, period. Watch your idle speed now, make sure it is the same as it was before he looked at it. Adjusting that thing is an easy way to make someone think there are bigger (and more expensive) problems with the car, than there really is. But, simply ask him how an ICV can thump, and please post up his answer here. I'd love to hear this. Is this an indi mechanic telling you this, or are you at the Lexus dealership?

[averona]

The mechanic said the mounts look fine, and that the thump sound he heard sounded hydraulic related. He said it may have been due to a real cheap oil filter that was used affecting the oil pressure. Also, he was able to clean the idle control valve, but warned me that the cleaner could get on the little motor on the valve and damage it. Who the hell knows? He wanted to keep it over night to let it cool completely and test it again. We'll see.

Nope. Sounds like the wrong diagnosis, ESPECIALLY on the thump. Ask your mechanic how in the heck an idle control valve can "thump"? You have a bad, driver's side, engine mount. Whether if it "looks" ok or not, I know it's that mount. That is the mount that takes the weight of the torque of the engine when you accelerate. The engine wants to lean to the driver's side when it's under pressure. Simply put, after 14 years, it's leaned enough on that mount to permenatnly compress that rubber to create enough of a gap to cause the thump. I would simply buy the mounts online, and take them to a mechanic and ask him/her to install them for you. Otherwise, you run the risk of getting exactly what you just got, which is a mechanic with a lexus in his garage with a bad engine mount "typical repair on all cars" with the idea that he'll make some money off of you. Replace the mounts before spending anything on the car.

Furthermore, I would make damn sure he doesn't mess with that idle control valve, period. Watch your idle speed now, make sure it is the same as it was before he looked at it. Adjusting that thing is an easy way to make someone think there are bigger (and more expensive) problems with the car, than there really is. But, simply ask him how an ICV can thump, and please post up his answer here. I'd love to hear this. Is this an indi mechanic telling you this, or are you at the Lexus dealership?

[Marklouis]

The mechanic said the mounts look fine, and that the thump sound he heard sounded hydraulic related. He said it may have been due to a real cheap oil filter that was used affecting the oil pressure. Also, he was able to clean the idle control valve, but warned me that the cleaner could get on the little motor on the valve and damage it. Who the hell knows? He wanted to keep it over night to let it cool completely and test it again. We'll see.

Nope. Sounds like the wrong diagnosis, ESPECIALLY on the thump. Ask your mechanic how in the heck an idle control valve can "thump"? You have a bad, driver's side, engine mount. Whether if it "looks" ok or not, I know it's that mount. That is the mount that takes the weight of the torque of the engine when you accelerate. The engine wants to lean to the driver's side when it's under pressure. Simply put, after 14 years, it's leaned enough on that mount to permenatnly compress that rubber to create enough of a gap to cause the thump. I would simply buy the mounts online, and take them to a mechanic and ask him/her to install them for you. Otherwise, you run the risk of getting exactly what you just got, which is a mechanic with a lexus in his garage with a bad engine mount "typical repair on all cars" with the idea that he'll make some money off of you. Replace the mounts before spending anything on the car.

Furthermore, I would make damn sure he doesn't mess with that idle control valve, period. Watch your idle speed now, make sure it is the same as it was before he looked at it. Adjusting that thing is an easy way to make someone think there are bigger (and more expensive) problems with the car, than there really is. But, simply ask him how an ICV can thump, and please post up his answer here. I'd love to hear this. Is this an indi mechanic telling you this, or are you at the Lexus dealership?

Averona, nc211 is right about the thump. my 95 LS had the same issue, replaced the mount and problem solved...my old mount "looked" ok, but it was compressed and dry compared to the new one. this mechanic you are dealing with doesnt sound experienced with the technical repairs of an Lexus. like nc211 said, if it is still driveable, i would take it somewhere else, buy the new mounts and tell them to replace the old ones. trust us, it will save you time and money. good luck. B)

[curiousB]

Time to find a new mechanic. Either he is guessing at the problem or worse he is just fishing for expensive repairs. nc211 and marklouis comments on the mount scenario seem to have a much stronger problem cause and effect story not to mention direct experience. Compare that to your mechanic who suggest a device designed to keep a steady idle speed do the motor while resting as the cause of a lurch. I know who I’d believe…..

[nc211]

Further more, if the ICV goes bad, I believe it will trip the check engine light. You don't have that do you?