Another 914 is Megasquirted, Megasquirt rocks! Options

[agrump]

Yes, it started!

I finally got all of the parts I needed to convert from carbs to MS. My car has 96mm pistons and performance cam (Fat FC442 280 dur.) so going with a stock system would not work.

I bought a box of FI parts from Ebay, I thought they were all from a 2.0 liter Porsche but it ended up being a mix of just about everything. The throttle body and plenum are 914 2.0 parts, the injectors are 1.7l Porsche, the runners are 2.0l VW bus and the fuel pressure regulator was from someones trash can. It was quite a mix but it all seems to work for the most part.

The megasquirt computer I’m using is on a version 2.2 board using the MS-I chip (soon to be upgraded to a ver 3 board and MS-II) with an LC-1 WB O2 sensor. I’m running the extra code to get 12x12 tables. I have not hooked my ignition into MS at this time since I thought it would be too much to figure out at one time. I’m also using the MS relay board.

I modify the stock throttle body for a TPS. I was able to install the TPS inside of the stock throttle switch assembly and wire it to the original connector. It looks like a factory job. I rebuilt a stock wiring harness to include the extra wires that I need and am using the original relay board to run the auxiliary air valve and to supply the MS board with the switched positive.

I’m using a fuel pump from CB performance. I had a problem with the fuel pressure being too low. It turned out that the fuel pressure regulator was not adjusting properly. I had to cut it open to loosen the internal nut so the adjuster would work. It works now but looks terrible, I will probably replace it. I also found that the PVC had a hole drilled through it. I glued the hole shut but will probably need to find a new one.

Once I fixed the regulator and the PVC the car started just fine. The idle was ok but it would skip every now and then. I checked the logs and saw that the processor was resetting. The problem was that the tach signal circuit was being grounded internally in the MS box. I brought the ground out of the box (XG1 mod) and it cured the problem.

I had the wide band correction turned on and let it determine what the proper values for the VE table should be at idle using MSTweak. Judging from my idle values I think my VE table is going to be very different then what others have posted. I’ll post them once I get it tuned.

The only major problem I have left is with the CHT sensor. I’m using that for the MS Coolant sensor and it is just maxing out way to fast. I need to artificially scale it to typical coolant values. MS will only read the sensor up to 215 degrees which is too low. I think that if MS “saw” the value of the sensor as being 180 degrees when fully warmed up instead of the actual reading of 215+ it would work better and give a more appropriate warm up curve.

Anyway, now that the car idles it time to road tune. Wish me luck!

Dean