Oldie but Goodie
Ive not had the luxury of scoping many old school Toyotas so I am not overly familiar with the ignition pattern. The first file is the IGF/IGT trace. Yellow is IGF. Red is IGT.
From what I can gather that is a good pattern. Yes?
Second file is the igniter ground to the ignition coil. This looks suspect to me because it does not appear to be going all the way to ground. The igniter itself is grounded to the chassis. I added a redundant ground,but there was no change in the pattern. I may be chasing ghosts here, because if there were a problem here,I would think I would see it in the IGF,yes?
The vehicle starts,runs for about a second and stalls. It will immediately set a P1300 code upon stalling. The final file is the CKP signal. (I know ,I have an 8 channel scope and Im using 2 channels at a time. These are the practices of the scope noob....)
IGT is ignition trigger. That is what makes the ignition coil fire. IGF id ignition feedback, think "distributor reference on a GM". The next step should be the scope the primary coil voltage and current, and coil output voltage. It is a simple ignition system, built the Toyota way.
So you see no problems with the files I posted so far?
Hi Rudy, the IGF signal looks good -- at the point where you are probing. But does the signal get all the way back to the PCM?
Riiiiiight!! Forgot that point. I am checking at the igniter,but maybe the signal is not making it to the PCM. I will check and report back.
This is from a 96 Camry 2.2 The blue CH A is the CKP The red CH B is the IGF The green CH C is the IGT The tan CH D is the coil neg with no grd voltage drop and 1.6ms spark time
Hmmmm so I should not be concerned with my coil negative then? The fact that it is not going all the way to ground is not an issue?
You should be concerned that there is a 1 volt ground voltage drop, when the module grounds the coil negative CH A CKP CH B IGF CH C IGT CH D, the voltage to the coil measures 14v and the module is pulling the coil primary winding voltage to ground for 3.3ms. The spark time measures 1.5ms
what sotware are you using to create those notes?? thank you
Not sure about Ray but screenpresso.com is my new best friend for marking up diagrams and waveforms
from where you took the capture the wave for igf and Igt are good , are you loosing spark? as default that system if the pcm does not detect igf , does not send out the fuel injector pw control, being said that it behaves like this : start stalled only start for a second or 2 , ecm is expecting igf as result injectir shout off occured. some how in the ecm something fail when you know are
Alldata shows this code occurs when the ecm does not see igf signal and shuts off the injectors A simple test is to probe the igniter out to the ecm, if your signal is there then go to the ecm and see if it's there, if it is, it probably a bad ecm, I just finished a 99 Lexus with a bad ecm, capacitor inside went bad causing a stalling at times.
Yeah getting to the PCM isnt easy on these old turds,but that is definitely on my list next week.
I think the old Camry PCM are in a great spot. Just drop the glove box door and pull the enclosure. All the PCM connectors are right there, (nice and CLEAN) and you can set your scope or meter right on the carpet next to your wiring diagrams and connector pin-outs. Nice and comfy! :-) (I had a 94 Camry just the other day.)
Im crazy busy and probably wont get back to this car until Monday or Tuesday. I did some more quick captures of the coil ground command from the igniter,when compared to Rays, definitely looks like a problem there. Its is not pulling all the way to ground in the short time that it is running. diag.net/file/f11z0hpu3… Looks like its only going down to .5v and even then not for
Well I could not explain the seemingly poor ground pulse from the igniter. I decided to refocus on the code for now,which resets immediately after cranking. As someone pointed out, the code sets when there is "no IGF signal for 4 consecutive IGT signals." I have never lost my IGF signal. The vehicle cranks,runs for a seond or 2 and stalls. IGF/IGT are present the whole time. I removed the
Just to follow up, a new computer fixed it.(yes it was sitting in the lot this long,waiting on a new ECM) ***As a side note I scoped the Igniter ground signal again with the new ECM installed and it looked exactly like it did above. Additionally I also scoped the igniter signal of a known good 1998 Camry and it also looked exactly like the pattern above. Im glad I did not spend too much time…
Rudy, good work on the fix. This capture is from a 96 Camry 3.0 CH A, the module pulls the primary coil winding voltage of 13.54v down to ground or 0v CH B IGT1, CH C IGF
Ray, this is quite intriguing that all Camrys you test pull the voltage to ground, and all the ones Rudy tests don't. Is it possible the modules for those California cars are different somehow? If I had to guess I'd say that the 0.7V voltage drop looks like a diode (for reverse polarity protection?), but I probably shouldn't even try!
Hi Dmitriy, a voltage drop in the power or the ground in the primary coil winding circuit, will lower the primary coil amperage draw, which could cause a short spark time across the spark plugs. This capture is from an 08 Volvo XC90 4.4 with some COPs misfiring caused by some COP ground voltage drops. CH A is the COP 6 ground wire with a 3.5v voltage drop, CH B is the COP 5 ground wire with…
Hi Ray, indeed, this resistive-type voltage drop in your waveform will disrupt the coil operation. However, there are other types of voltage drops, for example, in semiconductors. I have a few such components at hand and can demonstrate it on an artificially constructed circuit. But, if you are interested, we can get together and stick them into the ground path of a real ignition coil and see…
Hi Dmitriy, this capture shows a normal ground voltage drop thru a PCM driver. I am cycling the key on, off a few times. CH A is the output voltage of the relay to a solenoid, with zero voltage drop. CH B and CH D are the 2 feed voltages to the relay. CH C is the PCM grounding the relay coil winding and the normal ground voltage drop thru the pcm driver is 630mv
So, here the voltage drop is "normal" and does not affect the operation. Is there any rule of thumb to distinguish it from the "bad" voltage drop, or is it only possible with the amp-clamp?
The "rule of thumb" is to check power and ground voltage drops to any circuit that you are working on, before replacing parts. If you have a poor ground to a MAF or MAP or FTPS, you'll have sensor codes. A bad ground to a PCM will cause all kinds of problems. Crazy CAN waveforms and no comm on a GM truck could be caused by a bad block to frame ground strap. An engine that is cranking over…
I think my question got misunderstood. I don't think anyone here would recommend not to check power and ground voltage drops. But once the waveform is collected, what to look for? When is 630mV drop normal, and when it is not? Which drop matters most -- at the point when the coil is turned on, or when turned off? These types of questions. Well, I think I should not hijack this thread any…
Yes, start a new Discussion and explain what your capture is from.