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Here we go again...most bizarre problem yet


jacob80

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Just wanted to put in my 2 cents. A few months ago a friend of mine had issues with his ms that I installed for him. He had similar symptoms and it ended up being a broken solder joint on the DB connector(ground wire). Might want to check there, if you used a DB connector with the solder pots.

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Are you talking about the ground you have to solder for the megasquirt? I'm running a relay board, so there is a ground, switched 12v, and straight fused 12v that had to be soldered. Like I said, I will be going through all my grounds and possible just resoldering everything.

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Did you read the sticky on reset problems yet?

 

Yes I did, and I went through the entire thread. I'm going to go through it again and see what I can carry over to my car. That aside, I did find that my ground for my dizzy was questionable, so I went ahead and resoldered that connection and datalogged it. Here are the datalogs, the first one is starting it completely cold:

 

http://www.mediafire.com/file/izz2vinmyye/1-19-10 (1).xls

 

http://www.mediafire.com/file/dg1kywdey2z/1-19-10 (2).xls

 

Well, here is the first voltage drop to 7.9v. I will say that I noticed no resets this time just by sitting in the car. Here it is:

 

9003b7e3816331e5331a85af517512d55g.jpg

 

Here is a second drop, except this one is a drop down to 8v. Is this a normal behaivor? There seems to be no other variables affected by this voltage drop:

 

609cac7fa8269b39d32c0205c45a473b5g.jpg

 

As for the first datalog, those are really the only voltage drops, with 7.9v at the lowest point, is this okay?

 

On the second datalog is when a reset happens, although I did not notice it by sitting in the car. Here is the first reset/voltage drop:

 

3ce9823772edd8d08e3238b3d127ca545g.jpg

 

Does this look normal?

 

On to the next one. On this one, it isn't a reset, but it is a significant voltage drop. I believe I punched the gas pretty good and fast, but didn't seem to affect the variable there after:

 

67cbbe5ad1b50eb4eb98303191766d2e5g.jpg

 

Another one, looks like I hit the gas pretty good. Doesn't look like a reset but just a big voltage drop:

 

4cbe0bf97369d03f59ec155f750dfa045g.jpg

 

Let me know what you guys think, maybe I fixed it? My only question is, why are my AFRs so inconsistant? At one point, I locked in the spark advance shown here:

 

7b1ecc7c539533bb1cdf44436c542bd25g.jpg

 

Its very weird, maybe the pulse widths are too big? I'm completely guessing here...any help is appreciated fellas, thanks!!!

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FYI, those "resets" are just communication glitches. If the reset were real, SecL would reset to zero and stay there. A lot of the other odd spikes also seem to be communication related and not really happening, either.

 

So looking at the two datalogs above, would you conclude I am not expeiencing anything abnormal at this point? Are the inconsistent AFRs a completely different problem? I would assume so, but I think it's a tuning issue, I'll be starting another thread about that, as well this evening.

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Try this.

 

1. Cut the center leg on Q9 and Q12 or desolder it so it does not reach

the PCB.

2. Run a length of jumper wire from the center leg of Q9 and Q12 to an

unused pin on the DB37 connector.

3. Wire this pin to a 12 volt source in the wiring harness, separate

from the Megasquirt's power supply wire.

 

 

I just did this and it cleared up all of my voltage spikes.

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Also, if you decide to do this; when you choose an unused pin on the DB37 connector, check with your multi meter to make sure that pin is not grounded to the board. This will ground out the 12v that you ran back through the connector and can potentially damage something.

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I am not sure what path the OP is on, but he doesn't seem to know if his box has any real problems or just data logging to laptop problems. Until he figures that out he would be crazy to start hacking up the box with every fix that everyone suggest. I am not saying that these are not fixes, but the OP needs to get a plan and stick with. A plan that answers some basic questions, like is he really getting noise/reset problems or not. I have read all the threads by the OP and he does not have a solid troubleshooting plan and has not had one since the beginning of this problem. I know he has been trying all kinds of suggestions that are thrown out without understanding the real problems so maybe he will continue that way. This is a very very confusing path to be on.

 

I just want to mention a couple things at this point:

 

1. If firmware is being lost and having to be reloaded then you have a noise/wiring/build/install/reset problem, no question about it. I have worked through enough installs to see that only the ones with noise/wiring/build/install problems have blown away the firmware. The others that were clean well prepped installs have runs for many years without ever losing firmware.

 

2. If the laptop log shows battery voltage problems you need to confirm 100% that you have a datalog problem that is causing this or you need to confirm that the battery voltage is bad at the megasquirt box like the datalog shows.

 

3. If you reach a point where you no longer have blown away firmware, no longer see "real" resets and see good constant battery voltage at the megasquirt board then you are ready for the next step (maybe see if the car idles OK).

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I do not :( unfortunately :( if I can figure out how to get a more consistent idle and figure out autotune so it doesn't say "Tuning point outside window" perhaps I could start tuning and get a datalog and see what it looks like. Amy suggestions with these two remaining problems (hopefully!)?

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I do not unfortunately if I can figure out how to get a more consistent idle and figure out autotune so it doesn't say "Tuning point outside window" perhaps I could start tuning and get a datalog and see what it looks like. Amy suggestions with these two remaining problems (hopefully!)?

 

To get the car to idle you should not have any kind of correction or autotune turned on, you should be following the megamanual for tuning to get the engine to start and idle.

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To get the car to idle you should not have any kind of correction or autotune turned on, you should be following the megamanual for tuning to get the engine to start and idle.

 

That's right. The car idles, but has a hunting/wandering idle, what adjustment do i make to correct this? Adjusting VE tables values does not seem to work. Once I get a stable, consistsnt idle, I would like to enable autotune and datalog a gentle drive and see how it looks and monitor whether I get anymore voltage spikes or true megasquirt resets. Thanks!

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You know I'm starting to wonder if there's a problem with your serial cable to your laptop. If the sense or ground lines on the communications side have an intermittent short and are causing a spike through the comm system that could cause the errant logs and the firmware corruption. Do you have another cable you can try?

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Often a wandering idle can be caused by the idle mixture being too lean, tolerances on the TPS/MAP dot being too tight, auto tune could be attempting to readjust every time the mix gets slightly out. I would check you tables and make sure they're close to what you want then shut off the autotune feature and see it evens out.

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