Archive for January, 2010

Megasquirt rant.

Saturday, January 9th, 2010

Took a few step backwards over break, actually.

I was letting it warm up after mounting the battery box, and it began to run a little weirdly – MegaTune was showing that it was jumping RPMs, but I’d rev it in neutral a little bit and it would run fine for about 30 seconds, then do the same thing again. I figured this was because I hadn’t actually set the timing, so I decided to do that. Keep the car at 2000RPM and turn the distributor until the steel ball is visible in hole in the transmission bellhousing. Okay, done. Oh, what’s this? The timing light doesn’t fire on #1 at idle and the thing will just die? That’s kind of peculiar… Also, this engine can’t possibly rev from 900RPM to 1700RPM in one polling interval, and that’s kind of messing up my fuel delivery. Something’s wrong here.

Long story short, it got to the point where at idle the only cylinder giving consistent spark was #3 verified through test plugs and feeling the header primaries, and I learned how funny 4-cyl engines sound when they are running on one cylinder. I’m pretty sure that the reason for this can be attributed to the fact that my Pertronix unit was finally dying. Over the summer I ran an MSD Blaster coil, foolishly without the required ballast resistor, and let a little bit of the magic smoke out of the ignitor. By some stroke of luck, though, I let it cool down and it fired right back up, and I had no problems with it for about the next 1200 miles. I replaced the stock coil as well, and that wasn’t to blame, as it acted exactly the same with a replacement.

Oh, forgot to mention – when it managed to run on more than one cylinder, I decided “fuck it! I’ll just drive it around the block and at least feel good to have a somewhat drivable car!” Backing out of the driveway, I tapped the brakes to stop the car since I had to wait for traffic, no biggie. Go to let the clutch out, and the revs just drop. Give it a little gas and let the clutch out, same thing. Did I leave a brick or a 2×4 or maybe a small animal behind one of the rear wheels? What the hell? I poked around, didn’t see anything impeding my path, and disconnected the vacuum line to the booster, and it took everything I had not to let the car roll into the street.

So now I have to deal with a faulty booster.

Nik eventually came over and I figured that with a week to go before I left, we’d have plenty of time to get the car diagnosed and on the road – after all, he knows much more about MegaSquirt implementation than I do. I mean, he made a Fiat run, although I guess doing that is probably easier when you use aftermarket engine controls. Anyway. He comes over and we decide to swap the EDIS back on, after all, it did actually run however terribly so we could at least get to that point and see what was going on. After checking the hardware on the MS board, and replacing a blown optoisolator, and through a few of his “how the hell did this ever run at all like this?!” moments, I was confident that we’d plug the MS unit in, load up a basic fuel and spark map, and it would fire on the first try.

Well, that sure as hell wouldn’t adhere to the theme of this project. It did eventually start, but only as well as it did before… Well, I guess that’s acceptable. Swapped VR sensors and tested both with a multimeter; nope, those are both reading the exact same at cranking speed. Changed the EDIS4 module… Same deal, not working. Even went to NAPA and got a new coil, ran it for about 5 seconds and determined that it wasn’t to blame either, and managed to return it. All the while, the test plug is throwing a big nasty spark on all 4 cylinders. So this, combined with the fact that it was previously backfiring through the intake manifold, and blowing fireballs out the exhaust, should have immediately told me – it’s the timing, dummy.

So off I go to check the manual on how to install EDIS. Well, shit. Initially I had thought I put the trigger wheel on the crankshaft pulley on backwards, so I put it on 180° from where it was before. HOLY SHIT. THAT EXPLAINS EVERYTHING. It’s acting exactly like it has a distributor with the cap on backwards. I went to press the 36-1 wheel off the pulley in a 20 ton press (JB Weld you are no match for that beast) so I could align the missing tooth properly. According to the manual, on an engine where, facing the crankshaft pulley from the front, it spins clockwise, the missing tooth is supposed to be 90° clockwise of the VR sensor. Well, I had it 90° counterclockwise of the sensor. Yes, that HAS to be the problem. I grabbed a hot-glue gun to temporarily hold the trigger wheel on, triple-checked the positioning of the 36-1 wheel, and went to go fire it up fully expecting it to run perfectly.

Nothing. Not even a cough. WORSE than with the trigger wheel on backwards!

So yeah. That’s where I’m at now. The next time I’ll be spending any reasonable amount of time with the car is at the end of March. My plan of attack is… I guess just keep fucking with the timing until it runs? Maybe try to find another Pertronix unit to replace the one in my distributor? I left pretty frustrated, in about the same mood as when I left after summer break.

But right now I really don’t care which is part of the reason I didn’t update this thread.