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Old 07-02-2019, 12:45 AM   #10
cone dodging dilettante
redblockpowered's Avatar
Join Date: May 2015
Location: In bed, probably

BIG UPDATE: The transmission is in! Lots to write about now. I'll do a full writeup on the swap later but let's start catching up. I've done some 1500 miles since the swap and I'm really enjoying the car so far. In March it went up in the air to get swapped, two weekends worth of work turned into a little over two months thanks to some astonishing levels of rain here in Massachusetts, my schoolwork, and entering crunch time for my school's FSAE team. The M90 suits the character of the car a lot better than I think a T5 would (comfy ratios and shift action vs. those more suited to racing-type behavior). An unexpected benefit is that I've been seeing some 24-25 combined MPG out of the 940 since it was swapped, even now that I've turned the boost up with a GFB G-Force 2 boost controller. I think it would benefit from the factory 3.31 or 3.54 ring and pinion vs. the AW71's 3.73 but there's plenty to do with the car before that really even comes up on my radar. My dad and I have made a ton of progress on this car troubleshooting its numerous issues thanks to years of prior neglect, and over the course of the swap nearly everything in the drivetrain area was rebuilt/replaced/refinished and quite a few lessons were learned that I plan on documenting here soon.

Anyway, to catch things up to when the car finally became ready to swap:
I'm still struggling to diagnose an intermittent long crank, which I'm thinking is the result of the shoddy Chinese main fuel pump that whines incessantly. Quite a few issues were fixed that helped made it less frequent but that's about all that is left. Do88 vacuum hose in black replaced all the crumbly original stuff (a big improvement in idle quality), the throttle switch was adjusted, and the car turned out to have a rather dubious power stage installed:

This was replaced with a Bosch unit. I also pulled the intake off to replace what I thought was a broken breather box, but turned out to simply be a breather box that was not really mounted to anything and as such pissed oil everywhere. While I had the intake off I cleaned the throttle body with Delco Top Engine Cleaner and replaced the manifold and TB gaskets with new Elring pieces. The car still idled fairly poorly, until my dad tipped me off to something. It turns out throttle blades wear out/end up out of adjustment. The car was seeing some 2-5% throttle all the time instead of only the air from the IAC valve (which I also cleaned up with the same stuff). Resetting the throttle blade properly finally resolved my idle issues.

I'm doing something to the car almost daily now, which is awesome. I feel pretty good about how far it has come since I started, and it's only going to get better from here.

Oh, and some silly data I took for fun:

Sound level, constant 70 MPH: 73.9 dB (avg)

50-70 MPH, 5th gear (~13 psi, 13C, M90, stock exhaust):

Trial 1: 5.23 s (I think I jumped the gun here, hand timing isn't very good)
Trial 2: 5.99 s (probably most accurate?)
Trial 3: 7.22 s (started a few MPH short)
Average: 6.14 s

I need to revisit this and maybe revise my testing methods.

I think in-gear acceleration is a good "real-world" measurement for this car's use case, it's a street car that is usable on track and not the other way around.

Side note: I'm trying to be pretty thorough about documenting everything I do with the car, partially because it's fun and partially because I think it's a pretty useful skill to have. The black binder has all my receipts (yikes) and the green binder, as you would expect from the cover, has the 940/960/850 data pocket printed out because it's super handy.
1993 944 B230FT/M90 thread here:
2x 1991 245 B230F/M47 (LeMons car, street car)
I sell chips for LH 2.4!

Last edited by redblockpowered; 10-01-2019 at 05:55 PM.. Reason: shrunk pictures
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