CAM Sensor causing no start (1zz)

You will wear out the spark plugs without a cam sensor and have decreased engine performance. When the cam sensor goes bad the car has an ingenious strategy of preventing you from having an accident by an immediate shut down of the engine. It does this by firing the spark plug multiple times so that it will time it Where it’ll catch At the right time of combustion. You can get by temporarily but long term damage might happen.
you should run a diagnostics of the cam sensor wires, I believe it should read 5 V if I’m not mistaken.

I forgot what the normal values for the TPS sensor is but for sure it is not 100% at full throttle. I think I remember it being near 90 but it’s been along time since I’ve recalled.

@dev  Thanks very much DEV!

I knew it would hurt performance, but was unaware of the multi-fire scenario/operation.

I will check for 5V and peer into the BGB to see if I could have messed up the wiring.

Then switch back to other cam sensor and see if that works. 

I also switched the TPS was back when I installed the JDM engine.  It was newer, so I thought why not. Not sure what type of car it was out of.

Switching back is a little bit of a pain, but may test it out as well

Hopefully before the holiday weekend. So that I can enjoy the sun without hurting the car.

Appreciate the info - Have  a Great 4th!

The cam sensor should have a 5v power, a ground, and a signal wire.  You would need an oscilloscope to test the signal wire while the cam sensor is installed.  I don't have my service manuals near me, but I'll check them tonight or tomorrow and get you the wire colors.

On the TPS, I would check that the trottle stop screw is properly adjusted and lets the butterfly close completely and also that your throttle cable is adjusted properly lettting the butterfly open completely.  Take off your intake  and with the key on, engine off, open the throttlebody by hand in the engine bay and see if the TPS value will go higher, Like dev said though, it won't read 100%, somewhere in the 90s(I'll have to reference my service manual again for exact specs).  If it does, your throttle cable has slack and isn't opening it up all the way.  Lastly, I'm pretty sure the TPS sensor is slotted a little around the screws to fine tune adjustments.

Cam sensor shows mV with ignition on, and 12 mV when running.

Looks like I can go to Connector #E4 pin 15 on the ECU to check for continuity with my splice - but where do I pick up 5V if I have to bypass the wiring harness?

I really don't want to undo more of the harness.

I hate old wiring.....not sure what else could have caused this?  

I also switched out CAM sensor (before I got voltages) of course - no change.

Hope your 4th is going well.

thanks again for any input.

Rdawg

By the way NoCoolName - my Cam sensor only has 2 wires? Black and white.

I will try to check teh TPS later this weekend, but the low voltage on the Cam PS is now the top priority.  I found a link to a Toyota service procedure that says the two wires to the CPS should have 10K ohms to ground - so checking that next looking for a short in the circuit.

Thanks for the TPS info

so the signal wire (white) has greater than 20K Ohms resistance to chassis ground - so I think my splice and the wiring are good? But will check resistance thru harness

The grnd wire has only a few ohms resistance to ground - so also good. 

I cant see how this happened while fixing my coolant leak - but I guess my 20 years old harness didn't like being pushed out of the way when I removed the intake. and the battery was removed while I did all of this - hoping that somehow the ECM isn't the issue.

Posted by: @rdawg

so the signal wire (white) has greater than 20K Ohms resistance to chassis ground - so I think my splice and the wiring are good.

The 5V wire has only a few ohms resistance to ground - so I have found my culprit.  Problem will be tracing the fault.  

I cant see how this happened while fixing my coolant leak - but I guess my 20 years old harness didn't like being pushed out of the way when I removed the intake. and the battery was removed while I did all of this - hoping that somehow the ECM isn't the issue.

 

Hopefully you found the source.    

@dev nope - still digging in. didn't have much time on Sunday night to work thru. Its a daily driver when its happy, but I have a spare vehicle to hold me over.

Really hate diagnosing wiring, but I found the Cam and Crank sensor circuit in the BGB and the ECU checking.

Anyway - checking that ECU pin and the power at the CkPS is next on the list.

I put the car back up on stands - and hope to get to CkPS to check pinouts of that connector.  MR2's are a blast...when not broken

Sorry to hear. I wish I could help but all I remember is 5 volts when you probed the wires while the car is running. 

I have edited earlier posts.  The reason I hate wiring is because I am stupid...I was mis-reading the circuit posted above.  Need to recheck a few things (Signal wire to ECU thru harness) and stop chasing ghosts.

So -  a final post on this  

So I am reading up on ways to get the pulsed Cam Sensor reading and on the other site...and there IT is...

https://www.spyderchat.com/threads/help-with-start-up-i-searched-new-engine-block.123178/page-7

Roughly the same type of problem and the solution buried in the thread - and unfortunately it was in the options list from my original post but I got so tied up in checking continuity, etc...I never thought tp go back and just try it.

The JDM Engine must just have a different color code to CPS.  So, my splice was good - and all systems are fine... I just backed the wires out of the connecter - swapped locations - plugged it in and runs like a top.

What a pain, and worse  the 8 days I spent jacking around with this will make the MAF mod further down the priority list negotiated with the better half...Painting the bathroom and completing taxes have risen to the top!  The head gasket swap on the 2zz - way down the list  now.

Just glad it is back on the road and humming a long... Maybe someone else will learn from this after a JDM Swap

Posted by: @rdawg

So -  a final post on this  

So I am reading up on ways to get the pulsed Cam Sensor reading and on the other site...and there IT is...

https://www.spyderchat.com/threads/help-with-start-up-i-searched-new-engine-block.123178/page-7

 

Roughly the same type of problem and the solution buried in the thread - and unfortunately it was in the options list from my original post but I got so tied up in checking continuity, etc...I never thought tp go back and just try it.

The JDM Engine must just have a different color code to CPS.  So, my splice was good - and all systems are fine... I just backed the wires out of the connecter - swapped locations - plugged it in and runs like a top.

What a pain, and worse  the 8 days I spent jacking around with this will make the MAF mod further down the priority list negotiated with the better half...Painting the bathroom and completing taxes have risen to the top!  The head gasket swap on the 2zz - way down the list  now.

 

Just glad it is back on the road and humming a long... Maybe someone else will learn from this after a JDM Swap

 Happy for you.   

 If it is true that there is a different color code for the wiring for JDM harness  that is quiet relevant as someone else reported something similar long ago.  I remember that thread, full of misinformation and a lot of angry directed at me. 

@dev

to me the issue is the service manual. Maybe I need to go through it better - but I was surprised at the lack of detail for circuit diagrams.  

Still a little goofy idle, but hopefully that will settle as trims start to build up.