No IGT ?
I have No IGT signal to cylinders 1 & 2 ? (cylinders 3 and 4 normal) Fault #P0335 sets when cranking also. I have attached scope files for missing IGT signals and Cam/Crank waveform. diag.net/file/f7ggr96x3… At one point with the key on but not cranking and my pico leads hooked to cam and crank wiring the ignition system started firing rapidly (i had a spark tested on the #1 coil) ?? This made me think somehow my scope must be providing a ground?? So i added a secondary ground to the Crank sensor NE- (just a jumper wire to ground) Now i have spark to all 4 cylinders?diag.net/file/fw2d5de1i… I have included scope pattern as well. Can someone please explain to me why adding a ground to the crank sensor causes this change??
Have you load tested the wires from the sensor to the ECM?
It seems like a wiring or shielding issue to me. Since VR sensors create their own voltage (which is low) the circuits are very sensitive to wiring issues. It does not take much resistance to have issues, or if the shielding is damaged or not grounded you can have similar issues. I would unplug the wiring at the sensor and PCM, apply power to one end with a test light on the other. Measure
This is a fabulous puzzle that can be answered by a circuit simulation (coming up). I do have a question (or may be yet another puzzle) to the experts in driveability, though. With the CMP having 3 notches it looks like the car computer can control ignition to three cylinders from the CMP signal alone, but chooses not to (only cylinders 3 & 4 are reported to have spark)…
This is a known good 07 Camry 2.4 CMP, CKP, notice the CMP, CKP sync CH A CKP CH B CMP CH C is the B+ wire to COP 1 which shows each cylinder's COP's voltage drops There is a TSB 0192-12 for an updated intake cam gear Or remove the valve cover to and look for a broken or missing thrust journal at the number 1 intake cam bearing. The thrust journal limits the cam end play. The broken or
Ray thank you so much for that know good Cam/Crank waveform! The engine is obviously out of time. This poor Camry has been beaten around... neither me or my customer have ever heard it run...
Incredible information that actually helps to fix the vehicle, Ray! Does it also explain the electrical behaviour Bill observed?
The P0335 fix information doesn't explain the ignition system firing with the key on, not cranking.
Ray - you are correct and i am still curious about that too... Does anybody have a idea or answer??
Kind of a shot in the dark here, but depending on how the harness is routed for the IGT wires (are they bundled together, and do the run near where you were working?) , is it possible there is a rub through in the harness causing them to ground intermittently? Mentally I can picture that this would essentially act the same as ECM triggering, but I may be completely off base here. Just a quick
It was definitively grounding through the Pico somehow?? The spark was constant and rapid like the engine was running or cranking it did not stop until i disconnected my Pico leads ???
Just had a chance to pull up your original Pico files. Waveforms are pretty hashy, though I'm no Pico expert. I am wondering if you had a high enough resistance ground that whatever the input impedance is, it is less than that of your ground? Even then, you would need a pulsed (on/off) IGT control in order to fire the coil(s) more than once. So just adding a ground to the cam/crank sensors
My wild hypothesis is that: - The scope leads pick up some interference (like the 60Hz hum from shop lights), and the CKP input circuitry interprets it as a semi-valid CKP signal and tries to pulse ignition coils based on it. - Grounding CKP sensor makes its signal unusable, and the car tries to pulse all ignition coils based on the CMP signal alone (does the car pulse ignition coils with the
Bill, Did you happen to have a battery charger hooked up to the car or to the computer the pico was hooked up to? I am thinking along the lines of Dmitriy's 60 hz comment, but feeding through car battery and/or ac input of computer running pico.
I did have a power supply hooked up to the battery. My laptop was not plugged in. Maybe I could make it again but I am worried of possible damage to my Pico?? Certainly not worth that. Thanks for your continued thoughts.
I wonder if you remove the ckp sensor and then with the key on, wave a screwdriver near the tip of the ckp sensor, to see if one or more COPs would fire?
Ray, Perfect answer. Bypass ignition test so to speak. I can confirm that will work on a lot of systems. I've used that in a pinch before. It's definitely a possibility for why it was firing without cranking, although I'm thinking more internal fault of the sensor.
Ray, great share, thanks for your contributions to the industry! I used one of your known-goods from another site to diag an Accord 2.4 a few hours ago! Both cams were out, crank was lined up to cyl 1 tdc. Used engine was installed, crank no start.
Bill, Any updates on the car? Any more funny behavior from it?
Chris --- Ray supplied me a know good cam/crank pattern and proved the vehicle is out of time. My customer has been advised and quoted a timing chain / gear job (used car lot) and the vehicle sits covered in snow in my parking lot still..... Chris -- What is "Science of Diagnostics" that title sounds fun :)
That's my company name for my mobile diag business. It's a rip off of Sherlock Holmes. He always called what he did the "science of deduction". I'm not at his level, but it is a goal to aspire to.
I love it :) --- Thought it was a school or training center....lol I read your input regularly and enjoy it Chris. If i can ever be of help let me know. I specialize in imports
Shhh... you'll let my secret out. One day maybe a school, that requires alot more knowledge and alot more funding. I'm always open to help as well. I'm a jack of all trades, master of none. I dont do many imports so I may very well be taking you up on the offer.