3RZ No Spark

Info
1998 Tacoma
Regular cab
4 wheel-drive
2.7 3rz-fe
280,000 miles

Problem:
Engine will crank, but will not spark. There is no spark to cylinders 1 and 2. I have not checked cylinders 3 and 4

My engine blew through its main bearings a few months ago. I had the crank machined, block machined, installed new bearings and put the engine back together. I took extreme care to make sure engine timing was correct. Dropped engine in, plugged everything up and it will not start. The engine cranks fine.

New Parts
Crankshaft position sensor
Spark plugs
All gaskets/seals
Bearings
Rings
Battery

I am currently missing a knock sensor;however, the engine should start without that. I am getting voltage to the ignition coil connectors

Below is a diagram on the ignition coil connectors (2) and their voltage readings with the ignition switch in the on position (Its a poor diagram)

T1 T2 T3 T4
12v 0v 6v 0v

The secondary resistance between the two high tension terminals on the coils is 13k ohms which is within the range specified in my Haines manual.

I am stumped. Any suggestions?

 

The ECU may not trigger the coils without something from the knock sensor.
That sensor impacts timing.

 

I'll go digging around my garage for it. I lost it in the tear down process. Is it typical for a knock sensor to keep an engine from starting?

 

I installed the knock sensor. This did nothing, I've also confirmed that the knock sensor is not start critical. Any suggestions anyone?

 

Spark is triggered by 2 sensors. The crankshaft sensor, and the camshaft sensor. The camshaft sensor is in the cylinder head, underneath the throttle body. Make sure that the sensor was connected properly, because it is THAT signal that actually triggers the spark timing, while the crank sensor lets the ECU know where the engine is in it's rotation.

 

I'm about to go out and test connection/test it, do you know what the resistance values should be for it? Can't find it in the Haynes manual and I only have a 96 FSM. Thanks, this is the one thing I havn't checked.

 

Camshaft position sensor resistance is 835-1400 ohms when engine is cold and 1060-1645 when engine is hot.

 

The resistance values for the camshaft position sensor were within the range for a cold engine. The connector was shot;however I rewired it. No improvement in condition. Still cranking with no spark. Any other ideas?

 

After rewiring it, did you confirm that the connector at the ECU could read the correct signal from the CMP? Just mentioning it because sometimes a wiring repair won't always make a proper connection.

IF all of this is good, and you still have no spark from the coil then we can progress from there. First, did you check to see if you had spark on the other coil? One coil sparking and the other not will lead us down a different diagnostic path than BOTH coils not firing.

 

By the way, on the coil connector, terminal 1 is the 12V positive feed (Coil charge) and terminal 4 is the ground for this circuit. Terminal 2 is the "trigger" and terminal 3 is the diagnostic and ground path for the trigger.

 

Well I finally went the back end route and I've got a bad ECM. I'm buying a compatible used one off ebay and putting it in. Thanks for your help so far. Any tips for the ECU installation? Again, Thanks!

 

Get one that matches your truck 100%. Same engine, transmission. From what I have recently heard in another thread, those ECUs are swappable.

 

Alright, hoping this thread isn't dead and someone is still paying attention. So i've tried two replacement ECU's that have been tested and verified good. It has not changed the status quo. Still no spark to any plugs. Any ideas?

 

I will be in my shop again tomorrow, although I won't actually be open. I will do a bit more research then.

 

We will assume that the ECM was not bad then in the first place. Run some checks please. Check fuel pressure, and check spark on all 4 spark plugs. Then run a compression test, and a leakdown test. All of these procedures should be in the manual. We need to start with the basics.

Was any work done on the heads? If you replaced the piston rings I am going to assume you removed the heads to do this. So was any work done to the heads themselves?

 

I've got decent fuel pressure, I have checked spark on all plugs (new plugs) and have no spark on any of them. I have not checked compression, but replaced rings and pistons and cylinders are well within spec so there should be no problem.

The only thing I had done to the head was have it leveled so it would sit right on the block after the rebuild. There was not any warpage. Otherwise the head was just cleaned of carbon buildups.

I'm going to check whether the computer is reading the signals from the sensors and i'll get back to you.

 

The most important signals I am concerned about are the crankshaft sensor and the camshaft sensor. Those are used to time spark and fuel. Let me know what you find.

 

Please Please tell me someone found an answer to this!

I have the same truck and am having the exact same problem

I just pulled the engine and installed a crank kit.

No fire!

Please Help

Thank You

 

Hello. I have a 3rz-fe and ive got a similar issue. Mine will only run on one coil. Second coil wont fire. Replaced cam, crank and air flow sensors. Replaced coils, leads and plugs. Still no good. I have 12v on the main. 6v on the dig like yet the signal wire from the ecu is 0v to the firing coil and 1.5v to the non firing coil when the ignition is on. Any idears?

 

Check ground circuits and ohm the sensors. It is possible to receive a bad sensor. Also check the loom for and chafing which could lead to shorts.