Triumph

I'm 400 miles post replacement of water pump and timing belt and my car has decided that it wants to periodically shut down. Ten minutes after starting with a cold engine I'd be driving along at 40 mph engine light comes on and car has died. I'll shift to neutral restart go a short distance and the process will repeat three more times until I limp home. This has also occurred when I come to a full stop or take a right hand turn.

Some history: This problem happened about two years ago. I had the ECU rebuilt and the problem went away. Last week I sent the ECU back to the repair shop and they reported back that it checks out ok.

The mechanic who replaced the timing belt has since moved but prior to his departure he said the
IACV and vacuum were ok plus the idle isn't rough at all, no smoke from rear. I don't know what the default codes are yet but they usually seem so general on this generation.

I'm not mechanically inclined so any help would be appreciated. I've driven tthis car for 22 years and it's still in amazing condition. I hate to say goodbye to it but sometimes that's the answer. Thank You

dicer

Check the codes. I would suspect the cps.

Triumph

Thank You for responding. I'm waiting for my ecu to be shipped back.
Once it returns I'll follow your suggestion. One thing I neglected to mention
is that prior to the engine cutting out the engine runs very smooth and quiet.
I thought, based on other posts, that a compromised cps would have a rough
engine. Is that true? Thank You

dicer

A car that very commonly has a cps problem is a clk430 Mercedes, and it can run just fine and smooth, it just starts dying occasionally and then the day comes it just won't start and issues a crank position sensor code. And it is kinda hard to access for replacement.

Triumph

Now I'm really going to show how stupid I am. Got the ecu back today, installed it and the car started fine.
Here's the dumb part...Where can I find instructions on how to get default codes on '94 LS400?
what does CPS stand for? How many are there? Can an idiot install it (plug and play) or do I need just any mechanic
or a early Lexus mechanic? Are you familiar with any mechanics near Cape Cod Massachusetts.
Thank You
Dave

dicer

http://www.lexls.com/tutorials/intro/codereading.html

CPS ---------> Crankshaft Position Sensor
also the cam position sensor can be abbreviated the same.
Some times crank position sensor is abbreviated CKPS


If you just installed and all is good then there may not be any codes set, especially if the check engine light has not come on since the new install. Just drive and be happy.

Triumph

As a refresher, prior to the timing belt /water pump change 400 miles ago my car would idle around 800-900
now it idles at 600. I'm afraid to drive it very far from home so in an effort to get a check engine light I let it
idle for 20 minutes then took around the block with sudden starts and stops. The engine light did not
come on but when I backed up a few times in idle over garage floor lip the idle would drop to 200 then recover.
I apologize for being a haunt but I want to share these things just in case they mean something.
Have a great weekend.
Dave

timmy0tool

iTrader: (7)

this is purely conjecture so please correct me if I am wrong. if the battery was pulled during the TB change, the car has to relearn the fuel maps, one of them being idle. it takes driving around a few miles for the car to adjust to your driving style and situation.

Yamae

Regarding the relearn procedure, attached document below may be useful to know more. It is for a 1991 MR2 but almost the same contents are used for most of Toyota cars manufactured in 90s and later.

dicer

Re learn. Any car I put in my garage I disconnect the battery. I never on any LS400 have had any sort of problem just starting it up and driving after the reconnect.
Have any codes been extracted yet?
Things that need looking at are ECT, O2 sensors, egr, and idle control motor, if the bearings start locking and since they get pretty rough and dry it is highly suspect. If your ecu is now known good
the sensors etc are then next target.
Oh and if the o2 sensors have never been changed, change them. Your idle drop idle motor !

Triumph

Hi Dicer,
Thanks to all who have replied. I agree with Dicer in the 22 years that I've had this LS400. I've had 3 timing belt changes,
multiple battery disconnects and never experienced an RPM drop or anything out of the norm after reconnecting the battery.
What is blatantly obvious is the car came back a different animal then when it went into surgery for a new water pump and
timing belt. The RPM drop was apparent immediately after the new parts were installed. I'm not sure if the mechanic made
a mistake but I'm not a fan of coincidences.
The wires leading to the CPS were very close to the accessory belt but the sleeve over the wires appeared ok. The sleeve did not continue
to cover the wire bundle as it came closer to the cps. I moved the wires away from the belt as best as I could.
I have not received any error codes yet primarily because I'm afraid to drive it. Appears that at age 73 I'll have to get over that fear.
The only parts that have been replaced in 22 years other than normal maintenance items are: power steering pump (2x), water pump,
traction control sensor (10K ago), throttle sensor (10K ago), and ecu repaired (10K ago and recently confirmed as ok).

The parts you suggested I looked up on partsgeek and if I did it properly I'm suffering from sticker shock.
ECT= Not sure what it is.
O2 Sensors = W0133-1605030 @ $106.48
Crank Shaft Position Sensor = W0133-1617494 @ $75.48 and up
Throttle Position Sensor = W0133-1617542 @ $156.48 similar item??? 7553-05064677 @ $67.33
EGR Temp Sensor = W0133-1739519 = $227.48
Idle Control Valve (Motor?) = 7553-05492328 @ $810.33

If these are in fact the correct parts then i guess I'll have to get smarter about finding an error cod. The last
time I followed an error code it led to replacement of the throttle sensor and traction control sensor which
didn't need to be replace because the culprit then was the ecu