chadr

A couple weeks ago our 93 ls400 suddenly lost power and would barely be able to accelerate. I pulled off the road and had the car towed home where I decided it would be good to do the maint stuff I've been putting off -

fuel filter
timing belt
crankshaft seal
timing belt tensioner
timing belt pulleys
fan mount
water pump
thermostat
change coolant
distrib caps and rotors
valve cover gasket set w/ spark plug hole gaskets, and bolt seals
cam seals
air filter

plugs and wires were replaced 1 year ago

With that work done the car starts up and runs exactly like it did before. Turn the key and it fires up right away, but runs badly. Seems like some cylinders are not firing since the engine vibrates and nearly dies unless I press the pedal to keep the rpms up.

I disconnected the drive side coil connector and the car would not start. So it appears that side is working. Have not done the same check with the pass side coil yet.

I disconnected the air flow sensor with the engine running and I didn't notice the behavior change a bit.

There is no check engine light on. Are there still codes that may be stored?

Any suggestions on what to check? I did check the resistance of the throttle position sensor, crank sensor, cam shaft sensors, coolant temp sensor. All of these were in spec.

I'll look in the manual for hints on checking the air flow sensor.

Suggestions and question welcome. Thanks.

deanshark

It sounds like the timing is off. When you changed the T-belt, before you removed it were all the timing marks lined up? And when you put the new T-belt on, did they line up right? I hate to ask that but it is possible to put it on one tooth off. What you are describing is exactly how mine was running when it jumped time. (It jumped 6 teeth) I don't think it could be from your AFM b/c if it was bad and you unplugged it the ECU would go into fail safe mode and would run good. But then again, anything is possible. I would check the timing marks. Remove the top timing covers, turn the crankshaft pulley to 0, and see if both camshaft timing marks line up. If they don't try spinning the crank pulley around one turn. If they don't line up then the timing is off. Also, is it possible all that gunk you have is messing it up.

chadr

All timing marks lined up before and after the timing belt swap.

etex

Did you use OEM parts, or other?

chadr

Which parts are you asking about? I use some Lexus/Toyota and some aftermarket.

etex

Timing belt in particular.

LiCelsior

iTrader: (32)

i think ur car jumped timing, happened to me felt like the car weighed 8000 lbs and didnt want to move. crazy hesitation and found out my timing belt tensioner went bad. had to take apart everything in my friends driveway and re align that sonuvabish.

remove the spark plug covers and take a look at the teeth markings.

chadr

lexus/toyota

chadr

when the car acted up I tore everything apart to replace the belt and everything else. The timing marks lined up exactly where they needed to with the old belt. Car behaves the same way now.

Later I plan to check the pass side coil and take some readings on the air flow meter.

DonCorleone

iTrader: (6)

Because your car might have jumped timing before you did the work, when you did the work you put the belt on exactly like it was before, your car is going to run the same because you have it on the same incorrect timing.

etex

I have to agree with this. New belt must be aligned with cam and crank marks.

chadr

with the crank at 0 degrees the marks on the camshaft sprockets line up with the mark on the back plates. I checked this before removing the old belt, and after I put on the new one and rotated the crank about half a dozen times.

I was able to find someone locally who can test my air flow meter in his car later this evening. I can't get past the fact that when I unplug the air flow meter there is no effect on the engine behavior.

PureDrifter

iTrader: (10)

sounds like one side isnt getting spark...

sethjon

Good for you. The myth about all Toyota parts being better is such BS.

deanshark

Check that other coil when you get a chance. I still think it's a timing issue but, it could be anything. Here's the specs on the AFM along with other sensors. https://www.clublexus.com/forums/sc-...on-issues.html