1997 Sunfire 4 spd automatic repair & modding

[Daox]

Here is the modification wiring diagram. Assuming the ECU is easy to get to (its in front of the front passenger wheel apparently), it should be very easy and not take much time at all. I'll be ordering the parts soon. I don't have too many 10W resistors just laying around. Thats a big'un.

[Daox]

I got the switch all installed, but quickly realized that I had connected the switch to the wrong wire... I connected it to the tan/black wire, but on the wrong ECU connector. So, I made a really awesome oil pressure sensor switch! Sadly, this doesn't help out your mileage as much as you might hope. So, I undid that mod and pulled out the other ECU connector to get the right wire... except there is no tan/black wire on that connector. So, I have a bit more digging to do to get this mod working. But, first I have to get my friends Forester out of my garage. I'm just finishing up a clutch job on it.

I actually haven't been driving the sunfire much because I've been taking the CM400 (motorcycle) almost everywhere I go lately. But, the past two days I have had to take the car. This morning was my best trip in to work. The scangauge read 37.2 mpg as I pulled into my spot. Still, the tank is only a bit over 30 mpg.

[backpacker3]

I hate it when that happens. Well at least you know how to get a easy way to get a check engine light switch too. I'm sure turning that sensor on and off would not be to appreciated by the ECU

[Daox]

Haha, yeah. I'll probably try to trace the wire from the trans since it should be one of the only wires going to it.

[Daox]

Well, I threw in the new thermostat last night. Its still getting up to 200F on country roads (45 mph). That means on the freeway (65 mph) its going to overheat.

I did notice that if I shifted to neutral and revved it, it seemed to drop the temperature. Also, when I got home I felt the lower radiator hose and it wasn't very warm where the top one was scorching hot. So, I'm obviously still not getting much flow through the radiator. My guess now is either a bum water pump, or a plugged radiator.

Does anyone have any ideas on how to test out what to replace/flush?

[backpacker3]

I would be worried more about the radiator being plugged because if it is the limited flow to the water pump could mess that up too. If you take the belt off though you can try spinning the pump by hand you should be able to but if you hear scraping or grinding or if it seems stuck that could be your issue. If not you'll have to drain the coolant and pull the radiator off.

[baldlobo]

I'd look for information as to weather the water pump impeller is plastic or metal; plastic ones have a problem with coming loose and barely work

[2000mc]

Originally Posted by Daox

Does anyone have any ideas on how to test out what to replace/flush?

Heater performance with the fan at full speed.
Off hand I'd be geussing plastic impeller, like baldlobo. Also check for coolant around the head gasket at the left front corner of the head(as it's positioned in the vehicle) they usually leak externally before any other symptoms

[backpacker3]

Originally Posted by 2000mc

Heater performance with the fan at full speed.
Off hand I'd be geussing plastic impeller, like baldlobo. Also check for coolant around the head gasket at the left front corner of the head(as it's positioned in the vehicle) they usually leak externally before any other symptoms

I don't know that it would be the head gasket. He didn't say he was loosing or could smell coolant but that the car was running hot. I'm not saying it can't be a head gasket but at this point either a failed water pump or clogged radiator is far more likely based on the symptoms we have.

[Daox]

The coolant isn't milky nor is the oil. It doesn't appear to be loosing coolant either.

I'll try the heater test today, and if I start melting I know its the radiator. Thanks guys!