mfpthebronze

Car in question is a 99 manual with 93,000mi on the clock. Bone stock except for an unidentified header.
Newly installed DIYPNP MS2 with updated firmware (MsExtra 3.4.2)

With the help of forum members I was able to fix a flawed voltage circuit on the MS, and am now making 14v -- High voltage on NB1 alt output, new megasquirt install.

Since that time, however, I have been chasing a few issues that may be related:
1. Idle hunting once warmed up
2. Different A/F ratios on subsequent starts
3. Lost Syncs (31-cams not seen and 32-0 cams seen)
4. Car settling into a poor idle and then dying

Weirdly, I experienced none of these issues when the voltage regulator circuit was NOT working and sending 18v through the system, leading me to think I may have fried something.
I also noticed that when sitting at idle if I test the Idle Valve via CAN bus test, that the car will lose sync and die (this was not happening during first install/setup when the car was making 18v unbeknownst to me)
I took many composite logs, and none showed the loss of syncs except on startup - though there were occasional gaps where no data was recorded of Cam or Crank. Also, the cam signal was read in several different ways over the course of testing; seemingly not affecting the running of the car but maybe pointing towards a failing CAS?

I've done more in an attempt to track down the problem like tune settings, physically checking for vac leaks and removing and checking / cleaning the EGR and IACV.

I've attached my tune file, log and composite log, as well as a few pics of the different cam readings in composite logs. I understand all of you have your own projects to work on, but any help or pointers as to what I am undoubtedly missing in my .msq or in my troubleshooting would be appreciated!

Lexzar

iTrader: (2)

Check fuel pressure.

mfpthebronze

When the car dies it's an abrupt and clean shutoff, as if spark has been cut or something similar. No sputtering and stumbling. That being said, I'll go ahead and check fuel pressure just in case, as it's not going to hurt to start eliminating variables.

stefanst

iTrader: (1)

You're losing synch. There are two instances where your rpm drops. In both cases your "lost synch count" goes up. MS reports error code 31, but that doesn't really tell you anything. It's a cam or crank signal problem.

ByteVenom

I had a similar issue. I cleaned the Cam sensor and the crank sensor. My cam sensor had some junk on it from over 170k miles of use, and my crank sensor had metal shavings all over it. Also check the gap on the crank sensor. It should be about 1 credit card thickness away.

mfpthebronze

Ran the car again today, and took both a datalog and composite. Car was idling fairly fine, and then just flat died. Happened multiple times.
I am able to confirm that as soon as I begin testing the IAC valve in "output testmode", I can make the car die. You can see at the very end of my log where I play with the valve % and then it shuts off. Not like I make the idle slowly drop to dying or something, but like I've got solid idle, and it just quits. I've looked through all the data but can't seem to find anything that would tell me why the car is just simply shutting down. I must be missing something or operating under some incorrect assumption(s)

Please someone take a look at this log. I'm really struggling to understand what this could be.

I noticed that, but it seems to happen once the RPMs have all but died, making me think that those lost syncs are a symptom, and not a cause. I've taken about 20 min of composite log now whilst running and during probably 10 random shut-offs of the motor, and have never once caught an error or failed sync in the composite :/


Have already pulled, inspected and cleaned the cam and crank sensors. Cam was visually fine, crank was a bit dirty, but otherwise fine and gapped correctly with a feeler gauge. Both show no failures in composite logs either before or after servicing and the car is still dying unexpectedly.

mfpthebronze

Switched out the Megasquirt and installed the factory ECU today after work. Car ran great without any hiccups, drove fine, no idle drops or stalls.
I guess that means that there is an issue with settings or hardware on the megasquirt, but I am not sure which it is.

Anyone with a '99 have an MS2 .msq I can use? I would like to just try to idle on it and see if I still get the stalling and dying. If I don't, then that will at least tell me that it is a tuning issue, and something I can handle.

I'm in over my head if its a wiring or physical failure on the Megasquirt, as I am not nearly educated enough to know how to troubleshoot it correctly.

ByteVenom

I can post up my .msq once Im back home in a couple of hours. My idle isn't perfect, but the car runs and drives fine.

ByteVenom

Try that, it definitely works on my car, and I have a 2000.

mfpthebronze

Awesome, thanks for that. I'll have a snoop through the settings before I load it. Are you running COPs, Sequential injection, or anything fancy?

ByteVenom

Nope, I do not have a MAF in place however.

mfpthebronze

So, it doesn't seem that the tune was it, but maybe I'm getting closer to the problem.

I have been able to cause the car to die (hard and suddenly, no stumbling) every time I try to test the IAC in testmode. Also, whilst using ByteVenom's tune, I adjusted the fueling at idle and the process of burning the change caused the car to die in the same sudden fashion. Now, I have dealt with the "burn stumble" before, but prior to my voltage problems (after which the dying began) it always resulted in a quick recovery by the car. Post-voltage fix, I had to retune my fueling accordingly, and then the problems started.

I am thinking that tunerstudio is sending burns or signals to the Megasquirt that is causing it to momentarily check out of the whole making the car run game. That combined with an admittedly NOT dialed in idle tune could be causing the shut-downs. To test, I took the car for a drive without the laptop plugged in (I have always logged before) and never had a single hard die. Idle would dip silly low when coming to a stop and oscillate a little, but I expect that because my tune is not squared away down at idle yet. I'm going to continue testing this theory with more tuning of the idle and fueling, and then test driving without the laptop hooked up.

If you've had similar experience or insights, please chime in.