Vyndictive

Alright, First. I have my first autocross of the season tomorrow and I'm in the process of researching this problem.

Specs:
2001 AP1, 133k miles, fresh plugs, fresh oil, new trans fluid, SS brake lines, new rotors, AEM intake, Greddy TiC...

So, last night I took my S for the first longer driver since taking it out of storage. It was roughly 40 minutes with some redlining and WOT.

I saw the temp gauge hit 4 bars... and I noticed the fans were not on. So I turned the A/C on to get the fans on and the switch and the temp dropped quickly back to 3 bars.

So, I took the S home and parked it.

This morning I went to move the car and I noticed before even starting the car the temp gauge read 3 bars even though its 40 degrees outside and the car had sat for 14 hours...

Then, to my surprise, I hit the start button and the car cranked, sputtered a moment, then would not start. So, I inspected the coolant, oil, and battery. All looked good. It felt like it wasn't getting enough fuel.

So, after a few minutes of cranking, it finally started, but quickly stalled. Started back up again, seem to run ok. Then upon revving a bit it would hesitate and stumble a but. After idling a bit, it seemed to smooth out and rev like normal.

I turned it off and let it cool again. Went to start it again, same outcome; stumbling hesitation, finally ran ok. Temp gauge still read 3 bars.

I disconnected the battery is hopes to reset the ECU. Again, same thing, didn't start right away and still read 3 bars. However, after about 5-7 min of idling, temp gauge read 4 bars... now, I didn't do too much research, but I though at 4 bars the fans turned on at 220 degrees.... but I had no fans, and the head wasn't even hot to the touch.

So, this is where I'm at.... temp gauge is reading wrong... engine isn't starting when cold but ECU thinks its hot... but when the ECU thinks its hot (4 bars) its not turning the fans on.

I'm confused.

s2k16803

my money would be on bad coolant temp sensor... I dont know how to tune a car but through my experiences of being around tuners I know that the ecu reads the coolant temp when starting and adjusts parameters to get the car started. So I think its just as simple as the ecu thinking the car is hot when its not. When I first installed my aem ems on my car it was on the aem base map and had a really hard time starting when cold(this was during winter) similar to what you are experiencing, however I had a heated garage and leaving the car in there overnight got the car up to about 70 degrees and then it started right up. Hope this helps... Oh btw if you decide to change the coolant temp sensor it is located on the intake manifold under the runner closest to the firewall. If you need anything else just pm me.

Vyndictive

Hey, tried to PM you, but it wouldn't send.

How hard is the sensor to change? Is there a sensor DIY online someplace? Like could I change it today if Autozone or some common auto parts store carries the part?

Thanks again.

Vyndictive

Well, I had my autocross today.

After trailer-ing the car to the event this morning, I went to start it and move it off and the trailer and it read 4 bars on the temp gauge. It took at least 10 cranks to get it start and stay running. I let it warm up and all was well. After running for roughly 10 min at idle, the temp gauge was "pegged" in the red at 7 bars.

Now, the hood is up, the fans are not on, and that block was no where near 230 degrees.

So, my question is this: what sensor does the gauge read from? and other than a sensor... what else could cause this problem?

Further, if the sensor is reading this massive temp, is there another sensor that tells the fans to turn on? Because that sensor doesn't appear to be malfunctioning because the fans operated normally, I could here them kick on and off randomly.

Again, any help with this issues would be much appreciated.

Vyndictive

Ok... best way to get to the coolant temp sensor and replace it?

s02k

Its in the rear near the firewall.. I went in from the driver side, Mines doing the same thing, temp sensr is brand new.. think ive got air in the system so im going to bleed it tomorrow

Vyndictive

Did you remove anything to make the operation easier or just work with the very limited room you had.