schematics and diagrams: Engine stumbles and shuts off in forward gear on Toyota Land Cruiser?

Its a common problem,noticed on many Toyota car drivers.

It is possible that the transmission is acting up in drive and doing some things with the torque converter locing up and other things that will casue some stalling o stumbling for a second or two. Also it is possible that the EGR is failing.

Also in some cases the problem is engine harness being shorted out on the egr feeder tube from exhaust (buried underneath firewall)...this grounds out two wires when engine is hot and slight movement [right turn/moving off from a stop] these wires causes shutting down the engine only when car was in drive mode.

Try troubleshooting as described below :--------

You may have a problem wiht the EGR system on the toyota. Have you had it checked for OBD or fault codes? They can often help track things down. I will try to give you testing for the EGR system after the procedure to get the codes.

Toyota Trouble Code Info

96 & later are OBD2 systems and require a scantool
Note: We are finding that some 94 & 95 Toyota vehicles are
OBD2 compliant and require a scan tool.
Check your emissions decal under the hood to confirm
if you have an OBD2 compliant vehicle.

See the diagram shown below:-------

RETRIEVING CODES for vehicles before 96

NOTE: Not all trouble codes will activate MIL (CHECK ENGINE light)

Before proceeding, make sure the:
CHECK ENGINE light circuit is functional. It should be ON when the ignition switch is ON with the engine stopped.
Battery voltage is above 11 volts.
Throttle valve is fully closed (Throttle Position Sensor IDL points closed).
Accessory switches (A/C, etc.) are OFF.
Engine is at normal operating temperature (if possible).
Turn ignition switch to ON position.
Do not start the engine.
Place a jumper wire across TEl and El terminals in engine check connector.
Count number of flashes from CHECK ENGINE light.
If system is operating normally (with no detected faults), the CHECK ENGINE light will blink continuously
and evenly about 2 times a second.
Otherwise, the light will blink a number of times equal to the trouble code as follows:
The light blinks only (.5 second ON, .5 second OFF) when indicating a number.
The light will be OFF for 1.5 seconds between the first digit and the second digit of the code.
If more than one code is stored, the light will be OFF for 2.5 seconds before the next code is displayed.
Once all code(s) have been displayed, the light will be OFF for 4.5 seconds and then the whole sequence will repeat.
The diagnostic code series will continue to repeat as long as the check connecter terminals TEl and El are connected.
When finished, remove the jumper wire.
After repairing the malfunction, clear the codes from the ECUs memory.To test this you may need to rent a vacumn gage from a parts store. Most will rent them for free with a deposit.

1FZ-FE Engines

1.Check the filter in the EGR modulator for contamination and clean using compressed air.
2.Using a 3-way connector, connect a vacuum gauge inline between the valve and vacuum pipe.
Check that the engine starts and idles smoothly.For accurate system testing, the coolant temperature should be below 117°F (47°C).

3.Accelerate the engine to 2500 rpm and verify that the vacuum gauge reads 0 in. Hg.

4.Check that the EGR pipe is not hot.For accurate test results, the engine coolant temperature must now be above 127°F (53°C)

5.Check that the vacuum gauge reads low vacuum at 2500 rpm.

6.Disconnect the vacuum hose from port R of the EGR vacuum modulator and connect port R directly to the intake manifold.

7.Check that the vacuum reading is high at 2500 rpm. As large amounts of vacuum enters the engine, the engine idle quality may be adversely affected.
8.Remove the vacuum gauge and reconnect the vacuum hoses in their original locations.

9.Apply vacuum directly to the EGR valve with the engine at idle.

10.If the EGR valve is operating properly, the engine should misfire, run rough and possibly stall. Reconnect the vacuum hoses in their proper locations.

This details will help.

Thanks.

See below latest transmission related solved problems :--------