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Hi all, new member, I am having some slight issues but nothing I searched for seems to jive with exactly what is going on with my car. its a 99 LS400, Ive had it for about 5000 miles and it now has about 103k on it. Idk if these are related, but when I try to accelerate from a rolling stop (5-15mph), there is a very noticeable hesitation followed by a burst of acceleration. The tranny shifts seamlessly and the idle is fine. Also, whenever I accelerate from giving it no gas to depressing the gas pedal, no matter the speed, there is a very slight "thud", but i cant seem to pinpoint the location, might be the rear end but I cant exactly tell. The tranny mounts and engine mounts were replaced by Lexus about 10,000 miles ago, along with a "rear end service" (im assuming thats just changing the fluid). any insight would be appreciated.
i know every one on forums like pics, so here is one, '99 silver jade metallic
I have same year and color...Looks like the one that was for sale in Palm Desert, CA a year ago...
Look under "Sticky" section for commonn problems.
At 100K and 18 years, if not replaced, , (depending on your mechanical background...if not then have mechanically inclined person who uses a torque wrench) suggest the following;...
Uss only OEM or OEM vendor aftermarket parts.
1.) Spark plugs (Purchase from Rock Auto) If original then they are tired. Be very careful when removing connectors from spark plug coils..they tend to get brittle. .
2.) PCV Valve, PCV Valve grommet and both PCV hoses.with clamps (4)
3.) Pre-catalytic converter oxygen sensors (Rock Auto....wiring not as robust as OEM but a fraction of price) DO NOT use aftermarket brand here.
3.) Coolant temperature sensor and crush washer...resistive element gets tired with age....noticeable improvement ...do not use aftermarket.
4.) Check all battery connections and negative ground points....read my forum posting.
5.) Clean your airflow sensor with CRC Airflow sensor cleaner.
6.) Clean your throttle body and manifold airflow passages (check forum posting on particulars for 1998-200 LS400)...
7.) Drain and fill (but do not be talked into a "flush")your transmission with Toyota type IV transmission fluid. (About 3 quarts) I do this whenever the engine oil is replaced....do not reuse crush washwe.
8.).Check all engine vacuum hoses....they become age hardened and can leak at clamps...replace clamps
9.) Air filter ....a few bucks more for Toyota but seems better fitment over random aftermarket stuff
10.) Using synthetic engine oil???
11.) Valve cover gaskets and spark plug tube seals....the tube seals are likely rock hard and not holding vacuum...
Probably left a few things off....
Check out my "Extrude Hone" posting...this made a HUGE difference in mine.
As an aside....please PM me should you come across a spares car in same body color and agate interior.
at 90k it had all spark plugs changed, timing belt and water pump, rear diff and transmission service and at 96k it had all shocks replaced along with motor and transmission mounts. doesnt seem as if anything from your list could be causing the symptoms with my car, but perhaps it could be a throttle body or vacuum issue, but it really doesnt feel like it. anything else you could think of? When accelerating from a rolling stop its almost like it's revving and then catches itself instead of accelerating smoothly.
at 90k it had all spark plugs changed, timing belt and water pump, rear diff and transmission service and at 96k it had all shocks replaced along with motor and transmission mounts. doesnt seem as if anything from your list could be causing the symptoms with my car, but perhaps it could be a throttle body or vacuum issue, but it really doesnt feel like it. anything else you could think of? When accelerating from a rolling stop its almost like it's revving and then catches itself instead of accelerating smoothly.
You are familiar with how items listed could affect input to engine/transmission ECU?
UPDATE: so after a while the acceleration thud was getting a little more noticeable, this was also accompanied by a pretty hard "clunk" when shifting from R to D or vice versa. i took it into my mechanic, suspecting some kind of rear end or tranny mount issues, and he said there was serious play in the rear end. I then took it to a rear end specialist and he said he never has had to rebuild a Lexus rear end, however he did reiterate that there was something seriously wrong with the differential. Instead of having it rebuilt, which would have run around $1500, i found a 69k mile rear end from Car-part, had it shipped over and installed, got out the door at $575. all issues or problems with acceleration or shifting are now gone and the car feels brand new, especially since this has been going on pretty much since i bought it. i know i have read plenty on these and other forums about acceleration issues and shifting from D to R clunks, and in my case it was a bad rear end.
UPDATE: so after a while the acceleration thud was getting a little more noticeable, this was also accompanied by a pretty hard "clunk" when shifting from R to D or vice versa. i took it into my mechanic, suspecting some kind of rear end or tranny mount issues, and he said there was serious play in the rear end. I then took it to a rear end specialist and he said he never has had to rebuild a Lexus rear end, however he did reiterate that there was something seriously wrong with the differential. Instead of having it rebuilt, which would have run around $1500, i found a 69k mile rear end from Car-part, had it shipped over and installed, got out the door at $575. all issues or problems with acceleration or shifting are now gone and the car feels brand new, especially since this has been going on pretty much since i bought it. i know i have read plenty on these and other forums about acceleration issues and shifting from D to R clunks, and in my case it was a bad rear end.
Did the mechanic replace all rubber differential bushings?
What about differentisln pinion and side seals?
Half shaft rubber boots?
Were half shaft CV joints lubricated?
If not by mileage, then age of lubricants and the rubber parts..
Instead of having it rebuilt, which would have run around $1500, i found a 69k mile rear end from Car-part, had it shipped over and installed, got out the door at $575. .
all your diff fluid must have leaked out? I've got nearly 300k on mine and its original.
Originally Posted by Scraape
ebay has even better deals for used diffs.
on my 98 my diff went bad, and I bought a used replacement with 150k on it for $80 shipped, never gave me any issues.
The diff on my 99 might not be in the best shape either
There were no leaks. Something internally went wrong. Bought it from a 1 owner senior female driver. Unless her son (who was in his late 40s) was out beating on it in the meantime, its a mystery.
I checked ebay but almost all units had well over 100k, the ones that didnt were $400+
06-24-17, 05:18 PM
99 LS400 acceleration issues
