LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Delayed Engagement

Old 07-16-16, 12:58 PM
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Najeeh
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Default Delayed Engagement

Hello

My 1990 Celsior has a delay of about 1 to 2 seconds in engaging drive from park or neutral. It also jerks / jumps / lurches sometimes while drive or reverse is engaged or otherwise a harsh engagement into drive but relatively less harsh on reverse, see video below. It shifts smoothly into all gears while driving. Only the 1-2 shift seems a bit delayed when accelerating hard and if I manually shift from L to 2 it gives a surge upon shift.

Things already done are an oil flush with Toyota T-IV and I've also adjusted the TPS sensors and throttle cables. This did have an effect. The harsh engagement has half the intensity right now before the flush.

Old 07-16-16, 02:40 PM
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dicer
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Isn't this the same post from months ago?
Old 07-16-16, 08:26 PM
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Its the same problem. I haven't been able to find a solution. I thought that the 1-3 second delay in engagement was how these autos work but after driving a Toyota Crown with an A340E I found out that shifting from park to drive or neutral to drive has almost no delay. Same with reverse to drive
Old 07-16-16, 08:35 PM
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And you did fluid changes? Screen is clean and clear of debris? Was there any junk in the pan? It could be an internal leak or a restriction. If none of the easy fixes work then you will have a choice. Live with the delay or rebuild / overhaul the transmission, starting first with the valve body looking for restrictions and sticky or sloppy valves.
Old 07-16-16, 08:55 PM
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I did a fluid flush once (removed the oil pan, let the oil drain out and top up). I have to do that again as right now the fluid is pinkish brown. The filter was clean. I would also like to mention that before we bought the car, it had sat for 3 years driven only 1500 miles.
Old 07-16-16, 09:41 PM
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Yamae
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Sounds like the line pressure is not sufficient. I don't have the detailed pressure spec for a A340E but here is the spec for A341E used for a Celsior. It's from a JDM manual and probably figures are close.

You need to read those Japanese characters but figures can be understood. These two words are important for you. Ask me if you have any difficulties to understand the contents.
アイドル=idle, ストール=stall

According to shop owners, the low pressure is sometimes caused by the clogged cooling lines or the pump itself. When the strainer is badly clogged, you also need to clean cooling lines too using a compressor.
Attached Thumbnails Delayed Engagement-at-pressure-spec.png  
Old 07-17-16, 01:02 AM
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I'll check as soon as I can. Is there any way to check the shift solenoid operation?

Could low pressure also explain why
sometimes drive engagement is smooth to the point where I can't feel it and sometimes it's so harsh as if the car got rear ended?
Old 07-17-16, 04:13 AM
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Originally Posted by Najeeh
I'll check as soon as I can. Is there any way to check the shift solenoid operation?

Could low pressure also explain why
sometimes drive engagement is smooth to the point where I can't feel it and sometimes it's so harsh as if the car got rear ended?
Shift solenoids can be checked easily electrically measuring the current driven by the ECU. A current probe and an oscilloscope will provide you the measuring result quickly. A layer shorted solenoid consumes more current than a normal one.

Without knowing the pressure and its stability, it's not easy to step and assume further more. To measure the ATF temperature is also important.

The blockage of the cooling line is also the suspect as long as the ECU is properly controlling solenoids but this can be checked measuring the pressure of the in and the out.
Old 07-17-16, 04:27 AM
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I'll check the pressure as soon as I can get my hands on a pressure gauge. Could you tell me what the two rows on the table mean and what will be the required procedure. Do I just have to start the car and check the pressure or do I have engage it in drive or reverse?
Old 07-21-16, 08:19 PM
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Originally Posted by Najeeh
I'll check the pressure as soon as I can get my hands on a pressure gauge. Could you tell me what the two rows on the table mean and what will be the required procedure. Do I just have to start the car and check the pressure or do I have engage it in drive or reverse?
Regarding an English service data, I only have this for a 98-00. But this might be convenient for you to read.
Attached Files
File Type: pdf
AT service data.pdf (10.3 KB, 133 views)
Old 07-23-16, 01:01 PM
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Thankyou for the data. I'am going tomorrow to a transmission shop. I'll post my findings.
Old 07-23-16, 02:08 PM
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I already know the findings of a transmission shop. IT NEEDS A REBUILD.
Old 07-23-16, 03:54 PM
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Pinkish brown is still pretty dark. How did the ECU check out?
Old 07-23-16, 10:17 PM
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The fluid will be flushed again as I only took out the filter and filled the amount of oil that came out, about 4-5 litres. The ECU capacitors have recently been changed, they had not leaked as of yet and did not show signs of degraded performance. One other thing I noticed is that the engagement is very smooth when the car is cold. As soon it gets up to operating temperature or is near operating temperature, the engagement is harsh and jerks.
Old 07-24-16, 02:23 AM
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And what did the shop say?

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