Building a Microsquirt Daily Driver

[turbobaja]

Did a check-out this weekend, all looks very healthy. Each cylinder has 140-145psi cranking compression, not bad for only 7.7:1 CR. Leakdown measured 1-1.5psi @ 50psi regulated pressure, so 2-3%, still under 500mi. on the engine. Plugs all looked good and clean. Only sign of oil leaks is from the filter mount in the left fender/bumper mount. Think I need to reseal the NPT fittings and re-check the sealing surface...got a diaper on it for now. Motor is nice and dry. Oil pressure still ridiculously high. Seems to hit 65+psi when revved above 3K hot or cold. "Warm" idle is still 25psi @ 950rpm, over 50psi by 1800rpm warm, no such thing as "hot" with this engine yet. Running 4qts Mobile1 synthetic 5w-30.

I let it warm up before doing any pressure testing, and had a chance to let VEAL tune some of the free-revving cells in the 25-35 kpa region. I could see the AFR swing back and forth through 2-3K rpm. After letting VEAL tune for just a few minutes while I walked the active cells around slowly with my foot , the AFR was very close to my target #s. Unfortunately, that free-revving session must have smoked the wideband sensor. When I went to hit the road for a tuning session, the wideband started acting up. The display just stops moving and stays on a reading until the key is cycled. It will work briefly after a short cool down, but once it gets some heat in it, the reading stops moving. I took it for a highway cruise and blasted up a few hills and restarted at every chance I had, still couldn't get it to stay functioning for more than a few seconds after restart. I've got a spare sensor from the Baja I can try.

Using a velocity stack from a Dell 40 to smooth out the intake for now.

[MarioVelotta]

I like your new bell mouth Are you running any anti wear or just straight synthetic? Did you have a chance to try the baja sensor?

[turbobaja]

I like your new bell mouth Are you running any anti wear or just straight synthetic? Did you have a chance to try the baja sensor?

Just straight synthetic, no high zinc/phos fancy stuff anymore. Heard too much BS both directions on the subject so I figured I'd try just a good synthetic on this very mild valvetrain and see how it survives. I'd been running standard Chevron brand dyno oil in the old engine since we bought it (almost 10 years) without any signs of wear. Been spending an arm and a leg on high zinc/phos oil in my Baja, just to keep wondering if my ever-growing valve lash was due to a dying cam. Just switched it to 6qts Mobile1 0W-40 mixed with just 2qts of Amsoil hi-zinc ($$) 10W-40....so far quieter, cooler, cleaner, and for the first time since I built the engine, NO increase in valve lash after a few hundred miles .

Edit: Haven't had a chance to swap O2 sensors yet.

[Steve Arndt]

The only cam I lost in my life of building hot vws was with brad penn 20w50 high zddp and cam shield zddp. I now run Mobil 1 and things are fine after lots of miles. Just pick a blend that is above 1000 on zinc and phosphorus. ZDDP isn't everything. Newer oils have better anti friction factors without cat cogging zddp.

Karl, is it an LC1 (If so save your old sensors, they will work with a better controller most likely when you upgrade.You can also order sensors from your parts supplier at work cheaply, pretty much the same as amazon $).

S

[turbobaja]

Yep, it's an LC-1. It's what I went with for my Baja years ago and it's what Mario's packages come with too. I ended up having a bad sensor on my baja after quite a bit of tuning, new sensor fixed it. Bought 2 to have a spare when the first one went bad. I'll try swapping that spare sensor into the Super and see if it stays functional after warm-up. It's seen more extreme fuel trims in the EFI engine than the old sensor in my turbo/carb'd 2110 produced....as far as it would read anyway.

Good idea about getting parts through our Worldpac hookup. I just got a new set of KYB Gas-a-justs for the rear of the Super from the local VW parts supplier, had a Worldpac sticker on it when I picked them up....DOH!

[Steve Arndt]

I think the sensor cross references to a 2000 Jetta, but you know my memory, just go by the part number on it if you need one. They are priced right around $70

Steve

[Chip Birks]

I just get them off of ebay. Cheapest i've found. 60ish.

[turbobaja]

Kinda makes you wonder if there's a quality difference out there . When I first went searching for a replacement sensor for the Baja I called the part number in to a variety of places and got anywhere from over $250 from a VW dealership to mid $100's at various FLAPS, to the ~$55 out the door from O'riely's (IIRC) where I got mine from...working great so far. There's gotta be multiple manufacturers building the same part number, some with better quality than others...~every other part out there is this way at least. The box says Bosch, which are most likely made in China these days...good or bad.

[Clonebug]

My $58.00 Oreilly's Sensor is working great since Karl told me where to get one last year.

Napa wanted around $100 if I remember correctly but the best they could do was around $85.00 if they gave me my brother's discount.

[turbobaja]

OK, I swapped out the O2 sensor with a known good used one (learned the new sensor, ect.) and it's acting the same as the old sensor. Works fine on start up and after a few minutes it just sticks on one number. Seems to stop working faster with more heat (driving vs. free-revving). LED stays on solid like everything's fine with the LC-1. Any ideas folks?

[MarioVelotta]

What about the gauge in TS? Same thing?

[turbobaja]

Yep, same on TS.

[Piledriver]

reading rich or lean?

I found I welded my O2 bung a tiny bit off center from the hole in the tailpipe, so the sensor outer cover was making enough thermal contact to skew the readings in a not totally obvious fashion, was reading ~2 points rich at some AFRs, nonlinear.

Iittle work with a file everything read completely different.
(sorry, that's all I have)

Stick a voltage bridge from (vrev(5v)>gnd, a 5K pot will do ) as a steady (adjustable) input ~2.5v and see if the input wiggs out over time.(heck, a AA battery holder will work, as long as you don't swicth polarity)

[turbobaja]

The reading will stick at completely random spots. Anywhere from 7.4 dead rich to 21.9 fuel cut lean. Usually somewhere in the 13-14 area if it sticks when actually driving along. The fiance has reported a flashing display at times also, but I've not seen this myself to check the LC-1 LED for activity along with the blinking display.


On a bit of a side note...I hope. I wasn't able to communicate with the MS module last Saturday to confirm the WB readings in TS matched the gauge or not, so I called Mario to the rescue. He was trying everything possible remotely from his PC to mine and everytime he tried to connect to the module the engine would stall...wierd. As I was looking around the vehicle for possible causes, I shined a light down between the firewall and fan shroud inlet to find a nice sized rat's nest of wiring all wadded up....after being sucked into the fan ! I got REALLY lucky and no damage seems to have been done to the controller. The harness that got sucked up was the nicely bundled "auxillary" harness full of optional wiring we didn't use on this particular install, so the engine didn't seem to know or care about the situation. No damage to the main connector or anything, just a slightly shorter harness now... .

[Vee Dub Nut]

If TS is saying the same thing that the gauge is saying, I'm leaning towards a faulty LC-1 wideband controller.

As I'm sure you know, the controller is what makes the wideband "work", and the gauge and TS just read a 0-5v signal supplied by the controller to display/read the measured O2 value. So if the controller is spitting out erroneous signals/voltage, the gauge and TS is just going to report on what ever it sees.

LC-1's have a bit of a bad reputation online.. I've never had any issues with the 2 I've used, but others have...

I'd be slightly concerned that your wiring misshap hasn't goofed anything in the microsquit module, but from your symptoms, and especially with TS and the gauge agreeing, my money is on the controller itself. If all else seems normal, I wouldn't give the wiring misshap much more thought to this issue.