Help finding trigger of huge stumble at higher RPM

[jsmcortina]

- Clewett cam sensor to MS3...this wire runs all the way to the ECU under the passenger seat, where I believe I grounded it to the chassis...I'll check on that when I get home.
- 2 Bosch knock sensors to the chassis ground in the engine compartment
- The TPS wire, grounded to the same chassis ground in the engine compartment...this is the one I added just before this issue started and will try removing today

Olivier

Ensure that all sensors are connected to the Sensor Ground return wire ONLY. i.e. not to the chassis.

James

[ohecht]

Thanks James...I'll check again, but I'm almost certain I ran all the sensor ground to a common line running to Pin 7 on the MS3. I have run all the shields to chassis ground, though...do those also need to go to the sensor ground?

I really thought removing the shielded cable from the TPS would solve the problem after seeing the impact disconnecting the TPS had while the ignition advance was oscillating on Friday. I did that Friday night, and had about 45 minutes of uneventful driving all the way up to redline Saturday morning. Just when I thought the problem was fixed, it happened again in 3rd gear. Once it happens once, it seems to happen again easily, so there might be a temperature component to this somewhere. After studying all the recent logs again, I still think it's something related to the TPS. I need to take some time measurements in the log and calculate my own TPSDot in a few places, but I swear I see placed where the same amount of change in the TPS reading is not resulting in a TPSDot reading change for whatever reason, and I wonder if that's causing AE issues somehow.

My plan today is to do some more troubleshooting to try to eliminate causes...cleaning and repositioning the VR crank sensor, disabling AE to see if that prevents the problem, disabling knock retard, and checking the electrical connections for the fuel pump circuit to make sure there isn't an issue providing enough fuel at a stable pressure under certain conditions...there are a lot of relays in the circuit and I wonder if one of them is limiting the output of the fuel pump somehow.

I'm also looking at switching to a CNP setup using LS2 D585 "truck" coils to eliminate EDIS from the system since it's hard to diagnose any issues within the coils or modules...can anyone confirm that I can run two of these coils off of a single MSX ignition trigger? I've seem a few posts indicating it should work, but I haven't seen any confirmation from someone running a twin-plug setup with LS2 D585s...

Thanks again,

Olivier

[billr]

I'll take the easy one...

Yes, shields should be connected to an MS ground pin.

[ohecht]

OK, thanks Bill...I'll move the shield grounds and see if that solves the issue. The shield from the VR sensor goes to the EDIS module shield pin...is that OK?

I did some more testing today as I had more time than during my commute, and I think the issue is definitely some sort of RPM signal drop out. I've attached a log at idle...I was able to remove the ignition advance oscillation by turning off the Idle Advance and Idle RPM Timing Correction. Once those were turned off, the timing was steady at exactly 15 degrees and I started this log. The RPMs as shown on the tachometer were very steady even as the RPMs in Tunerstudio oscillated between 700 and 1300. The MAP was also fairly steady, staying between 43.8 and 46.The fuel pressure oscillation was much worse today...no idea what's going on there but it didn't seem to affect the car when the other oscillations were not happening. I'm not sure how to address fluctuating fuel pressure like that...I'm just monitoring it through the MS3 and not trying to control it.

I've also attached a Composite Logger file from when the idle was oscillating. I can't see any issues in this but maybe an expert can...one of the reasons I'm thinking about getting away from EDIS is so I can see directly what's going on with the crank signal...I think the EDIS module "masks" that data from the MS3 loggers since it only send the PIP signal to the MS3.

So, it seems that the timing oscillations were caused by the perceived RPM fluctuations...I'm now looking into the VR sensor and EDIS modules. I don't have the SAW wire from the MS3 to the EDIS shielded since I read a few posts saying that only the PIP wire needed to be shielded.

Olivier

2015-11-22_15.49.27 rpm flux MAP tach and timing stable.msl

2015-11-22_15.42.47 oscillating idle.csv

2015-11-22_18.46.43.msq

[billr]

I know nothing about EDIS, but am guessing termination of the VR shield there is appropriate, as it's my understanding that the EDIS module is where the (crank) VR signal is detected/processed.

[jsmcortina]

EDIS is a reliable autonymous ignition system and I would suggest that you'll likely encounter more problems if you remove it.

Do you get stable timing with the SAW wire unhooked? Confirm this.

James

[ohecht]

OK, it happened again...not on the way to work...the car was smooth all the way to redline on the way in. It always seems to happen during the second drive of the day, and it happened on the drive home, almost 10 hours later, though...

The problem is definitely something with the RPM signal. In the log snippet below, the actual engine RPM is not fluctuating, even though the reading in the MS3 and TS is all over the place. This oscillation in the RPM signal is causing all the secondary effects with timing advance, etc. I have no idea what's going on with the fuel pressure...that massive oscillation (down to zero repeatedly) started yesterday but I don't think the fuel pressure is actually oscillating that much, and it's certainly not going to zero. This signal is oscillating even when the car is driving perfectly smoothly, so I think that level of actual variation in the fuel pressure would be very obvious. I've tried driving without the fuel pressure sensor connector connected to see if that made a difference...it did not, but now I'm wondering if I should just remove the entire circuit. It is one of the two things I added the night before all this started (the other being the shielded wire to the TPS).

James, I think you're right about sticking with EDIS for now, and I checked the timing with the SAW wire unplugged (I removed the diagnostic jumper)...it was perfectly steady at all RPMs at 10 degrees. I also confirmed that the timing with the SAW connected is changing appropriately as commanded by the MS3. I also had the engine in it's bad oscillation mode and tried removing the SAW jumper...no change to the oscillation although the range of the RPM oscillation moved a little bit.

Still stumped...is there any way to verify the crank VR signal in an EDIS setup? I'm not sure what would make that signal so steady up to all RPMs sometimes and then cause it to get stuck in the oscillation mode).

Thanks again to all the experts out there...hoping to figure this out soon!

2015-11-23_17_modified.msl

[Matt Cramer]

Not much you can do to check the VR to EDIS signal without an oscilloscope.

Any chance either rhe sensor or the module is getting too hot?

[billr]

Maybe I am way off-base here (no experience with EDIS), but doesn't the OP already have most of a "non-EDIS" system in place? Already having 36-1 and sensor, MS3X, and waste-spark coils, couldn't the OP just add a coil driver module? Just for test purposes, that may be a worthwhile effort.

[kjones6039]

Maybe I am way off-base here (no experience with EDIS), but doesn't the OP already have most of a "non-EDIS" system in place? Already having 36-1 and sensor, MS3X, and waste-spark coils, couldn't the OP just add a coil driver module? Just for test purposes, that may be a worthwhile effort.

That's all I had to do, when I switched! I just used my existing EDIS coils and added one of Jeans driver boards. Very inexpensive change over, btw.

Ken

[ohecht]

Thanks...I may look into that option just to see what's really going on with the VR signal and eliminate the EDIS modules from the equation. I don't think heat soak is an issue as the modules are far away from the engine (where the CDI coil originally was), and the issue will always reset itself with a restart no matter how hot the engine. The issue also starts even when the car is almost completely cold and certainly not anywhere near temps that would start to cook electronics.

I found the source of the massive fluctuation in the Fuel Pressure signal...now it's back to just a lot of oscillation (varies from 30-40 psi at idle but I still don't think the actual pressure is oscillating). The issue was that I had turned on the debug data in the knock settings when I was looking at knock as a potential cause of the issue, and that started communicating the knock sensor data for one of the cylinders on top of the fuel pressure sender signal, since I had that sensor set up as Generic Sensor #1.

Last night, I didn't have time to do too many major changes, but I moved some wires around to try to get less noise in the VR and other signals. I moved the crank sensor wires to a spot where they're as far away as they can get from other wires and nowhere near any high voltage wires...they had been bundled with the 12v power wires going to the EDIS coils. I also rerouted the cam signal wires to make sure they were not near any of the spark plug wires.

So far today, the issue has been different in two ways: 1) it's started to get triggered at idle and at far lower RPMs. It happened briefly just leaving my driveway this morning, and the engine has been stalling at lights now despite having a rock-solid idle and well-behaving idle valve up until today, and 2) it just happened again at higher RPMs in 4th gear on the highway (log snippet attached), but this time the RPMs were absolutely stuck at 2509 RPMs while I was still driving with the engine near 4k RPMs. I could see it clearly in TS and the engine didn't recover until I dropped the RPMs back to 2509 and then everything went back to normal. Before this happened, I had two separate trips on the highway going near redline without issues and thought the trigger of the entire thing had somehow moved from high RPMs to low RPMs somehow.

This tells me that moving the wires did somehow change the characteristics of the issue, even though it's still there...hmmm

Olivier

2015-11-24_12_modified.msl

[kjones6039]

I have tried to refrain from comment here because I know absolutely nothing about MS3. But, I did find something that is distressing to me, in the last log you posted!

During a time period of some ~79 seconds, several traces never change. (show no activity)

RPM remains at 2509.0 even though TPS varies from -39 to 1.8 over the same time period
MAP remains at 81.1 during that entire time (ain't happenin' in the real world.............)
Spark Advance @ 24.3 which doesn't surprise me too much since engine load never changes
Did you notice that PW never varies either? 4.577 throughout.......... (another one that can't happen....)

My opinion (that no one asked for).......... I think you have more than one issue as opposed to a single one, such as noise or whatever.....

Sorry that I can't offer a solution for an MS3!!

Ken

EDIT: another issue in the same log.... RPM goes from ~3500 to ~1600 within about half a second.... Not too likely either!

[ohecht]

Thanks Ken. I only noticed the RPMs doing that but I haven't had too much time to study that entire log yet. Could something like that be caused by a failing component on the board itself? I've had someone suggest to me outside this forum that a failing voltage regulator on the MS3 board could cause such an issue.

I just rewired the crank sensor and PIP wire to make the shielding as good as possible and separate all the wires as much as I can...I'll see tomorrow if it makes a difference and keep looking at other options if not.

Since EDIS doesn't send the actual crank signal to the MS3, are the trim pots for tuning that signal useless, or could I still adjust those to get a cleaner PIP signal from the EDIS modules?

Olivier

[ohecht]

Just an update here for everyone that's been helping. I'm sure the issue is noise in the PIP signal to the MS3. I can induce the issue at idle by changing the R52 and R56 pots and then "cure" it, but I haven't been able to find a combination that keeps the issue from occurring completely. I'm waiting to get an oscilloscope I ordered to read the signal directly as the composite, trigger, and tooth loggers aren't helping me enough so far.

I've also read in this article that says adding a 10k or 20k resistor to the crank signal wire could clear up "high RPM breakup", and I might try that.

http://www.diyautotune.com/tech_article ... _index.htm

Despite being convinced this is a noise issue, I'm still not sure how it could have started so suddenly. There was no hint of this issue at all for weeks driving the car and then it was just there permanently one day...that seems like a strange way to have a noise issue like this start.

Olivier

[ohecht]

I used a scope to get the PIP signal as clean as possible, but it didn't see too sensitive to the pot adjustments and the problem remained.

After reading some information about "Tach Period Rejection", I finally looked at the Noise Filtering menu under Ignition in TS. I don't think I've ever touched that menu and definitely should have looked at it sooner. I turned all the noise filters off, and the problem definitely changed and got a lot better. The car is now smooth 99% of the time all the way to redline, with only an occasional dropout in the RPM signal that instantly recovers...see time stamp 44157 in the attached log snippet. I hope this cures the issue, and wanted to see if anyone knew the best settings to use in the Noise Filtering menu if I want to turn it back on and screen out whatever's causing the occasional missed signal. I also had one log after making this change where the RPM signal indicated 15k RPMs for one record.

What's interesting is that, in the documentation, it says that "the Noise Filtering menu option is disabled if "EDIS" or "EDIS multispark" have been selected as the Spark Mode". I'm definitely set to EDIS for Spark Mode, so it seems like this entire menu should be inactive, but it was active and the filtering was turned on.

Does anyone have any ideas for settings I could try if I want to reactivate the noise filtering to get an even more stable signal, either in the software alone or with hardware changes like adding a resistor to the PIP wire and/or the VR sensor wire(s) to the EDIS?

Olivier

2015-12-02_08_modified.msl

2015-12-02_09.32.58.msq

Input at 5k rpm after adjustments.BMP

[ohecht]

Here's the scope trace of the PIP signal at idle...

Input at idle after adjustments.BMP

[ohecht]

Here's the latest:

Turning off the noise issue has made the issue much better...it has not gotten caught in the RPM signal oscillation since. What it does now is almost always have a period where the RPM signal drops out for a single record in the log, always under heavy load such as full throttle acceleration in 2nd or 3rd gear and around 5k RPM. You can see that issue in records 88 and 110 of the attached log. MSQ is also attached.

I also caught the issue on the Trigger Log...see record 39 of the attached Trigger Logger. I spent hours adjusting R52 and R56 yesterday with no improvement in this issue. I've put a scope on the input signal, but I don't see much change in the shape of the signal with the pot adjustments. It definitely looks like the system is missing another tooth on the 36-1 wheel other than the actual missing tooth. I have the VR sensor about as close to the trigger wheel as possible...less than 1 mm. I don't think the software-based Noise Filter would help with this, as it seems to be just about filtering out probably noise signals based on their timing and duration, and I think my issue is that a real signal is being missed occasionally.

I'm also curious about some of the settings I've always had in the Ignition Options menu and whether they could be part of this issue. I've had "No Prediction" instead of "1st Deriv Prediction" set under "Use Prediction" in the Ignition Options menu. I also had Dwell Type set to "Fixed Duty" instead of "Standard Dwell" which is the setting to use for most installs according to the documentation. Not sure if that matters at all for EDIS, though...

And something really weird: I tried switching the "Spark hardware in use" setting from "JS10 spark" to "Tacho". I didn't change any connections or hardware at all and didn't expect it to work, but it fired right up like that. (It also worked on "Falling Edge" and "Going Low", which surprised me). Anyway, I tried it and the RPM drop seemed to go away. I had to spend about 30-40 minutes retuning the VE table but each time it pulled very smoothly all the way to redline. I also noticed that all of the readings in TS were "changing faster" than they used to...the entire screen of gauges seemed like it was more active, almost like the actual processor itself was working more quickly. I also had to adjust all the PID settings for the WBO2 and CL idle, too, so it really seems like the sensitivity of the whole system was increased. Throughout the whole tuning process, though, the RPMs were smooth all the way to redline. I did notice some very small dips in the RPMs on the way home, but it was happening far less often then when using the JS10 Spark setting.

Olivier

2015-12-05_09.48.21.msq

Before Pot changes - see record 39.csv

2015-12-05_09_modified.msl

[hobieboy]

Not much help but I am monitoring very closely... I had the exact same issue back in the Spring with very similar set up (930 engine) and I also had miss under high RPM & load.
I was never able to solve that. I have the entire set up out right now since she somehow developed a grounding issue (after I changed an exhaust gasket) to a point where she won't even run.
Good luck & hope someone can help.

[Dennis930]

If you decide to switch over to LS-2 coils, I can confirm that the MS3X card will handle two LS-2 coils paired together for dual plug operation. The input impedance of the coil logic circuit is high enough to not overload MS3X components. Hope you get it figured out.

[ohecht]

Thanks Dennis and Hobieboy. It is incredibly frustrating. I'm going to try another VR sensor under the theory that the signal is actually missing a tooth on it's way to the EDIS module, since nothing I've done on the MS side has made the slightest difference with this issue. I drove about an hour today and the issue is still there, so all the changes from late yesterday didn't make a difference.

Dennis, thanks for confirming that about the LS2 coils...I have a mind to just switch to that setup since I was thinking about it anyway and hopefully it would change out enough hardware and the setup to eliminate whatever this issue is. Where to mount all those separate coils is one of my concerns...as I'm debating centralizing them vs. locating them close to the plugs as a "CnP" setup. If you have a 930 as your user name suggests, do you have any pictures of how you mounted the coils?

Thanks again,

Olivier