Confusing no spark issue

[gotlag]

Am currently working on an 99 Eclipse GS. Was running the car and it suddnly sputter then died. Would not restart. Pulled codes and showed intermitent cam signal. Replaced cam sensor, no more code, yet still no spark. Have replaced cam sensor,crank sensor, and ECU. Have Checked all wires from sensors to ECU.

Here is the confusing part....
Using a scope, the cam and crank sensors both have great patterns. Even probed into the ECU to be sure the ECU was recieving the signals, and it is. The injectors are being pulsed. The coil has power, and a solid voltage signal to both coil triggers (pins 1 and 3), but no break to cause the coils to discharge. Stranger still, if you disconnect the cam sensor and run it with the crank sensor only, then it starts to produce spark and tries its best to start, but still won't. Plug back in the cam sensor and all spark dies.

Has anyone else ran into this issue. I did go over all mechanical aspects such as cam timing and they are all good. I just can not figure out why having the cam sensor in place causes a loss of spark.

Any ideas greatly appreciated,
Andy

 

[Eclipse45150]

Check your battery vlotage when you try to crank it, sounds like mine did, when under load it was only gettin 9.4 volts, if the battery is not pushin higher than 9.6 under load then it won't go. Lemme know if this works

 

[gotlag]

Thank you for the input. Feared that earlier, and verified it did not drop below 11.4-11.6.

 

[BigRand]

Try to jump the car, and see if it cranks.


Also if you can get your hands on a verified working coil pack, you should probably swap it out.

I'm assuming your getting spark across all four wires, if not you might not be getting it to the two that need it to fire up in the right order.

 

[gotlag]

Thanks for the input so far.
I guess I should be more clear on the issue I am trying to fix. With the cam sensor installed and verified via a labscope to be working correctly, the ECM no longer triggers the coils to fire. It powers the circuit completly, just does not ground pulse the coils to fire. Remove the cam signal, then it does. Using a Modis I can input the trigger signal and the coils fire then as well. I easily have 12+ labor hours going over this, and I feel it has to be something simple, yet over looked.

 

[Jungy]

I had a weird prob like this with my car too when i first baught it... I never could find any problem with the wiring, dis-2, or anything for that matter, but I ended up rewiring the coil pack wires from the ecu to my dis-2 and the dis-2 to the coil and it has ran great since. So my question is are you getting anything from the coil signal wires at the ecu?

 

[slow96rs]

I just went through same thing with my car replaced cam sensor because of oil leak, crank sensor had no continuity replaced it, replaced coolant temperature sensor, still no start, checked fuel pressure and found good(make sure to check fuel pressure) after all that started unplugging misc. sensors pulled manifold absolute pressure sensor check engine light came on then vehicle cranked terrible idle won't rev above 4000 rpms will replace when dealer gets part in check this maybe same problem with your car. I know it doesn't say much about my expertise on DSM's but I am a technician at Honda dealership. I worked on problem for over 10 hours with no help from Honda boys.

 

[gotlag]

Problem solved, and I thought I should share what it was. The dowel pin on the exhaust cam sheared and the cam was about 40*'s retarded. It was hard to spot because the marks on the gears all lined up, and looking beind the cam gear bolts I could see the pins. It wasn't untill I removed the valve cover with everything lined up that I could see that the holes drilled in the cam was not facing straight up. Pulled the cam, reinstalled a new pin and put it back in, and now the car fires right up.
I am confused as to why the scope read OK, but at this point it dosn't matter anymore.

Thanks for the helpful suggestions.

Andy R

 

[Locke]

Not a common problem, by far. Glad you noticed it, got it figured out. Hope 40 degrees isnt enough to cause valve damage, with all that cranking.

Good information though, who'd have thought. Good job.

 

[dr1665]

Points given. Such excellent sharing of trouble shooting proceedures. There is a LOT of information in here for anyone tracing a no-spark scenario in the future. I would have never suspected the dowel myself. So random!

 

[gotlag]

Thank you both.
Lucky for the owner of the car, it has aftermarket dished pistons (going for a turbo upgrade) that the valves made no contact.