so have you driven around and logged the ignition and tach signal when it cut out yet?
Brian
so have you driven around and logged the ignition and tach signal when it cut out yet?
Brian
Originally Posted by turbovanman
I've tried, but I can't get the triggering to catch it. I need to get a screen capture program on this laptop. I'm going to investigate adding some better grounds today. It does seem like it was running significantly better yesterday after I changed how the alternator was grounded. Perhaps that was coincidence, but it has never run so consistently well for as long as it did after doing so. I think I used close to half a tank yesterday chasing this.
ETA: Cleaned up the ground locations very thoroughly with a wire wheel on the drill. I also drilled a 1/4" hole at the battery ground and used a 6mm bolt. It is holding the terminal much more firmly, and I'm sure has formed it to the contour of the body for better surface area. The area on the firewall actually had some paint flaking when I removed the ground there. It doesn't look like there was very good adhesion in that spot of the engine compartment when it was repainted after the fire. In all truthfulness, that was a less than ideal ground at this point. As my grounding improvement yesterday may have made a difference, I'm hoping this might finally solve the problem. It's back to the scope otherwise.
Last edited by cordes; 06-19-2023 at 03:09 PM.
OK, I'm going to let the car cool off and get ready to log the tach signal, key power, and the two HEP signals. Hopefully that sheds some light on something. I'll get a screen capture program too.
ETA: I'm using a grounding scheme such as the one in the attached image. It has made no difference, nor has removing the tach wire.
Ch1 Ignition on J2 feed
Ch2 Tach feed
Ch3 Ign reference sensor signal
Ch4 Fuel Injector Sync Pickup Signal
I'm not sure why one signal is so dirty. I adjusted the ground location of the "probe" to be with the rest of them and it made no difference. Could this noisy signal be the root of the problem?
Skip ahead in this video. A few seconds before the end of this video, the car cutout pretty hard relative to the current state of affairs. I don't see anything of note though.
This video shows the car running right as rain. I messed with the time a little in case that might help people.
If anyone has triggering ideas or any other how-to info, it would be highly welcome.
Last edited by cordes; 06-19-2023 at 09:00 PM.
Looking back at previous screen captures from the scope, I'm fairly certain that the scope didn't auto calibrate the channel with the "dirty signal". I tested again last night, and even with the key on, the signal was very rough. That doesn't make sense to me since both signals use the same power and ground. I guess this HEP could be bad, but I'll check on other cars first to be sure.
The next thing I'll look at will be the rad fan output. That's the one thing I've left that's not technically needed. Could flyback voltage be inducing a problem? Could the relay have a short in the winding causing just enough amp draw to freak out the LM? We'll find out!
When I zoomed in on the Fuel injector sync signal wire, it didn't look like noise, but a wave. I guess I should look at a known good signal to compare.
ETA: It wasn't the fan relay wire.
Last edited by cordes; 06-20-2023 at 11:04 AM.
The Daytona looks a little different. A saw wave I guess. Would this make a difference? I guess I could once again pull the computer and PM for another swap.
Not surprisingly, the Minivan has a different look to it. I presume this is due to the SBEC nature of things being sequential injection and all.
At this point, the only things I haven't replaced are the injectors, coolant temp sensor, charge temp sensor, and the fuel pump. Is it time to replace any of that? I'm at the end of my rope here.
no codes? LoL... seriously tho, if a sensor (or wire to a sensor) are flaky would think it would trip a code?
guessing you already tried these...
injector harness ground to manifold on fuel rail mount bolt?
intake to firewall make sure clean aluminum on intake not paint?
check all fusible links?
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I would think it should trip a code to for how bad it breaks up when it's at its worst. It won't store a code for the event though.
I have a good ground going from the bolt with the fuel rail grounds directly to the firewall. I have checked the fusible links and they all looked very good. One interesting aspect of all this is that it does the same thing regardless of which wiring harness is in the car.
I just put the LM/PM out of the Daytona in the Lancer with a cal I made to match the 2 bar +40s. It runs very well, but still cutout once on a 16mi drive. I'm going to see if there is an option in T-LM to not have a charge temp sensor. I highly doubt that's it, but it would be an easy way to tell. Then I would be down to the injectors, coolant temp sensor, and fuel pump for things I haven't changed.
I think I'm going to reinstall all of the pins into the LM connectors, as that clearly wasn't the issue.
ETA: If nothing else, I've finally found a bad component. The charge temp sensor was bad. I would initially give a value on my meter, but then instantly show an open condition. It wasn't the problem though. It never threw the charge temp sensor code, which is interesting. The sensor itself looks period. On with the search.
Last edited by cordes; 06-20-2023 at 05:42 PM.
Hi Brian,
I am on a fuel pump kick (long story) so if the fuel pump or its power is acting up no code is shown.. Yes I had this issue, bad feedthough at the pump hanger. Repair at a rest area on Interstate 71 while I was visiting a foreign country :-)
I still have the occasional cutout that I will checkout after SDAC
Regards,
Miles
DD '87 Sundance T1, SLH with rear disks
'87 CSX #432 2.5 CB TII, SLH
That is interesting. I'm down to that and the coolant temp sensor. Since it's fed by the Z1 circuit it could make sense that an insane fault could be freaking out the PM and disrupting the ASD or something.
If you unplug the coolant sensor does it act up in limp mode?
Regards,
Miles
DD '87 Sundance T1, SLH with rear disks
'87 CSX #432 2.5 CB TII, SLH
I haven't tried that, but I will tomorrow. Right now, I'm thinking the fuel pump is my next realistic target. It's on the Z1 circuit at least.
Agreed. Fuel pump issues won't throw codes. But if you can log secondary ignition, and the fuel pump cuts out, you should see a change in the firing line of the ignition when it goes lean... This is how I diagnosed a random cutout issue on my charger. When I saw two companion cylinders go lean.... It made it pretty obvious it was an injector driver. I was able to parade the cylinders and input the firing order into the scope, so I knew which ignition pattern belonged to which cylinder. I used and old school scope lol. I learned early on when I got into automotive, fuel pump issues don't throw codes. That has changed with technology now as a lot of cars have fuel rail pressure sensors.
I wouldn't be very concerned about the signal "noise." Sometimes that is just how things look on a scope imo.
Thanks for all the feedback. When I zoomed in on it, I wasn't concerned at all. There's no way it would be that consistent on two vehicles if it were a signal problem. In my highly amateur estimation of course!
I used this scope. Not very mobile but I was able to get it to act up in the bay by blocking the wheels and loading letting the clutch out in gear.
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Not mobile indeed. So far, I'm thrilled with my scope. It's lightyears above the super cheap tiny job that I picked up years ago. It hardly worked. Now I can run down the road logging fairly well. I'm sure if I was actually trained on how to use it, I would think it's even better; or perhaps that it sucks. I'll stay blissfully unaware.
I looked it up on Amazon. I don't think it sucks lol. Scopes are tricky and take a lot of time to learn. Does yours have a pickup for secondary ignition?
I think it does. It's what I was measuring the primary ignition with. It's the HT-25 probe.
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