1997 Sunfire 4 spd automatic repair & modding

[rednic79]

yeah I would think some aero mods are in order... I am also fairly sure that engine off coasting is not good for the three speed. so if you pulse and glide, leave it running. be carful playing with the lock-up. the clutches are not meant to take much abuse.

[Daox]

I'm not really wanting to dump too much time or money into this 1997 car. The picture shows its good side. The other side has a crumpled up passenger door, typical rust under the gas door, and a few other things. I'm certainly not willing to dish out for a new tranny, manual or automatic. Its a commuter and that is just about all. My commute is a little less than 14 miles a day (3,650 miles per year). I don't really plan on using it for a whole lot more than that. Even then, I plan on using the bike most of the summer.

I will probably block off some of the grill. Thats an easy mod and I have some coroplast laying around already.

I think the biggest gains are in the transmission area. The evidence being the difference between the manual and automatics mileage in the EM garage here. The engine is capable of giving high 30s to 40s, but the automatic just eats away at it like crazy. But, I should be able to literally add a switch that I have laying around for a free mod that locks up the torque converter and see a decent bump in mileage. If I get real ambitious, I may start playing around with an arduino and the shifting solenoids to make it a manumatic, but I doubt I'll have time for that.

[vskid3]

I don't know what's worse, the terrible mileage the auto version gets, or that people bought them new anyway.

Good luck squeezing more mileage out of it. Any possibility of weight reduction?

[Daox]

Eh, I dunno. I could pull the rear seat, but it really doesn't weigh much at all. I'd like to keep the passenger seat in case I have to use it. Other than that the car could use a good spring cleaning. Nothing else really comes to mind.

[Daox]

Well, first things first, maintenance! I've done a bunch of work on this car already. I ended up replacing the sub-frame, the entire interior, pretty new wheels and tire, and a few more bits off of a 2003 Cavalier that my bosses daughter crashed and I scored for a few hundred bucks. That was back before winter though, and the car was never aligned. I just made the appointment today to get it aligned. That should hopefully help out FE a little bit. I can see the front tires have worn a fair amount faster than the rears...

[Daox]

I got the car back from having the alignment done. One front tires were out 5/8" total. So, I'm sure that'll help out with the mileage (and tire wear!)

I also just filled up for the first time. There was about 300 miles on the tank and she drove 200 of them, me 100. We got 26.2 mpg. Not as horrible as I was expecting considering the cold weather we've had. I'm shooting for 30 on the next tank though!

[2000mc]

Originally Posted by Daox

While the manual guys with the same engine are getting mid 30s to 40s for mpg, the automatic guys seem to have trouble besting 30 from what the garage here says.

but how long do the tanks last, and what kind of driving?

for example
details: Moved to the suburbs... Goodbye MPGs
thats where the mpgs drop to about 25


i had tanks in the 40s w/ my auto when i burned a tank every few days, but now that im just under 4miles to work, i was getting low 20s this winter, and filling up less often

[baldlobo]

considering you have the 3t40(th125c), i'd check out what the final drive ratio is.

then there's two ways to change it one is changing the diff; the second is changing the chain drive(this one you don't have to pull the whole trans apart).

[backpacker3]

Maybe even the 4 speed would be better that's what I have and I can hit 35 mpg though over on j body guys with sc and tc'd engines are getting 40-45 without even trying with the manual trans it's definitely a worthwhile swap. I know if I only had the 3 speed I would probably be swapped already for now though I'll wait it out since my trans is pretty healthy though. If it ever does go though it wouldn't get another auto I can tell you that.

Btw that front end always seems like it has way better aero options than mine since it's flush to the hood on mine they added a grille that would be a huge pain to try and block.

[Daox]

My commute is 7 miles one way. So, its pretty short. Thankfully, most of it is 45 mph country roads which is ideal.

I got my scangauge back from being borrowed last night and hooked it up this morning. Its obviously not calibrated yet, but it showed me 27.2 mpg in to work this morning.