hard start and rough idle

[1G9S9T7]

I have 97 gst with a 6 bolt swap. I seem to have issues with it starting and rough idle. When it turns over, it takes a few tries before it starts. Upon starting, it will die if you try to press the throttle. After a few cranks, when it finally stays running, it has a rough idle like at 600 or less. It will run and drive just fine. I did some research and from what I can see based on the research, a lot of people say the coolant temp switch. Now I plan to do my millionth boost leak test and check the isc for the millionth time but I have a question more pertaining to the cts. I am not specifically sure which it is. The way this engine is set up (pulled out of a previous 2g) there are two switches in the water neck that plug into the harness my means of a prong such as a typical light socket and there is a plug that has two wires that plugs into a small sensor on the water neck. All three of them thread into the neck like a screw. I don't know which is what. Also my TB had a type of screw in the back that fell out. It had a prong on top of it but when tightened, it put more pressure on the plate where the throttle cable connects and I was basically told it helps keep the throttle plate from slamming shut. I don't know what it's called but apparently it's prone to falling out because the original TB didn't have it and mine popped out. I was wondering if it had anything to do with my issue or if it was even needed if anyone knows what I am talking about.

 

[tjohn23]

That little prong thing is the idle switch it lets the ecu know that the throttle plate is closed and to override the throttle position sensor. Yea needless to say it is probably one of your many issues since the TPS always read at about 11% open with a shut throttle, less air more fuel equal bad idle, that is why it runs fine but cant recognize that the throttle plate is closed and to cut the fuel

coolant switch would more than likely cause a overheating issues or even idle surging but one step at a time just replace the idle switch and go from there

 

[1G9S9T7]

Yes the idle switch . Could never put a name to it. I plan to replace it with a long screw instead. I used it to lower my idle to about 800 rpm but it was backed out so much I guess when the throttle slammed shut (letting of gas pedal quickly) it knocked it out. I plan to replace it when I get time. I do believe idle is much smoother while it's there. I was checking out my 2g harness and it seems I only have one plug for a coolant temp sensor where a 1g uses two, the one for gauge and the one for engine control. Is this correct or is something wrong?

 

[tjohn23]

im not sure about 2g but the 1g has two sensor one for the gauge and is lower housing and im not exactly sure

 

[Turbomaniac18]

Im having almost the same poblem i rebuilt the upper end of yhe motor and its hard to keep it running it seems to drive ok but my air to fuel gauge is reading really rich could it be my idle position screw? Or my bov is not reciculated i had to get a new hose could that cause it any help would be great

 

[craig4g63]

Bov not recirculated on a MAF car can cause problems between shifts and all the time if it leaks.