1997 Sunfire 4 spd automatic repair & modding

[Daox]

I had a pretty ideal commute in this morning that netted me 35.4 mpg on the scangauge. Its going to need to be higher than that on average to get me up to 35 mpg, but its a good sign. There is still no TCC lockup switch installed yet.

[backpacker3]

Nice that's a pretty good number for the crappy 3 speed it has. Have you considered pulling the spoiler off yet that should help with aerodynamics.

Edit: looking on j-body.org I found some info about the AutoTrans Interceptor it seems like it might be a lockup switch and it's available for your 3 speed auto but it seems like the TCC solenoid is a little weak or is at least a problem point on the 3 speed so it's recommended that you install a trans cooler with a torque converter switch. There were a lot of posts with people having issues with the TCC solenoid.

[Rishar]

Couple things I'd like to share regarding the car. Drove a 96 same engine for 5 years.
The engine normally does sit about 195F.
The cam/crank sensor error is common and most likely not the sensor. It will only effect how efficiently it starts but will run fine.
The rear spoiler actually helps with a cleaner seperation than no spoiler as it's the one near window. (From what I could gather)
Engine off coasting is not ok. Uses a mechanical pump for transaxle which quickly overheats when engine off neutral coasting. I heard lots of interesting grinding/whining sounds after starting moving again.

[Daox]

Originally Posted by backpacker3

Nice that's a pretty good number for the crappy 3 speed it has. Have you considered pulling the spoiler off yet that should help with aerodynamics.

Edit: looking on j-body.org I found some info about the AutoTrans Interceptor it seems like it might be a lockup switch and it's available for your 3 speed auto but it seems like the TCC solenoid is a little weak or is at least a problem point on the 3 speed so it's recommended that you install a trans cooler with a torque converter switch. There were a lot of posts with people having issues with the TCC solenoid.

Thanks. I was pretty happy with the first tank of almost 31 mpg. We'll see how the next one goes.

I haven't tinkered with the spoiler at all yet, I'm not sure I will.

I'll have to look into that interceptor. I've heard of the TCC solenoid problems too. Thankfully, a TCC lockup switch should decrease transmission temps due to decreasing the pumping losses through the torque converter.

[Daox]

Originally Posted by Rishar

Couple things I'd like to share regarding the car. Drove a 96 same engine for 5 years.
The engine normally does sit about 195F.
The cam/crank sensor error is common and most likely not the sensor. It will only effect how efficiently it starts but will run fine.
The rear spoiler actually helps with a cleaner seperation than no spoiler as it's the one near window. (From what I could gather)
Engine off coasting is not ok. Uses a mechanical pump for transaxle which quickly overheats when engine off neutral coasting. I heard lots of interesting grinding/whining sounds after starting moving again.

Thanks!

I think the thermostat isn't fully opening up. When I got home the other day the lower radiator hose wasn't very warm (wasn't cold either), and the coolant temp on the scangauge was over 200F when I parked it a few minutes before.

Is there any way to fix the crank/camshaft sensor error?

Thanks for that bit on the spoiler.

I haven't tried engine off coasting, since its an automatic so I just assume thats and issue. Thanks for verifying it though.

[MetroMPG]

Originally Posted by Rishar

The rear spoiler actually helps with a cleaner seperation than no spoiler as it's the one near window. (From what I could gather)

Official source or educated guess? I would have made the same W.A.G. about that particular spoiler.

[Rishar]

Mostly educated guess given the air flow over the vehicle.

As for fixing the error, I can't say. It could be the sensor or anything inline of it from wiring to a faulty alternator. I gave up on after awhile myself...my mechanic saw that same fault in a few sunfires and it was never the cam sensor XD

I will say, despite the auto 3 being inefficient and that fault, cruise control at 55 still got me 32mpg and playing with highspeed eoc I got 47 with average speed of about 52. And I did eoc p&g for nearly 160 miles. Only tried starting it while it was already running a couple times. Not a good idea woth that 3spd though

[Rishar]

200 definitely won't hurt it any though. I'd check the fan. I had lots of issues with it not always coming on and finally wired a toggle to it. That was after replacing the relay. Another thing I never found the cause of . I do miss driving that car. Loved it in winter

[Daox]

So I've been doing more reading about the shift kit deal, and the 3 speed in the Sunfire. Apparently, the transmission is not electronically controlled, its all hydraulic. The only thing electronically controlled is the TCC solenoid. Thus, the electronic diagram showing shifting solenoids for the 4 speed only. So, I'm hoping that the TCC switch should be simple to do and not cause any issues. It appears that the ECU grounds the switch (since the other wire comes from the fuse box and fuses are kept close to the battery). Someone from the jbody forum even tore apart one of the shift kits and shared the resistor values so I shouldn't get a check engine light when I install the DPDT switch for the mod.

[backpacker3]

Cool should be interesting to see the results.