I really do need some help with this and hope you are up for it.

My car was running great after I changed the wires, plugs, fuel filter and injectors. (I'd recently changed the waterpump, opti and alternator too.) The miss I had been complaining about was completely gone and I was as happy as Duntov on a track. A few days later though, my car quit starting on the first try. I didn't think much of it as it would on the second or third attempt without a problem but then a couple of weeks later when I started it, the engine shuddered as idle surged back and forth and then stalled. I'd start it again, and it would do the same thing. I put it in gear to leave the parking lot and lurched and shook and then stalled. The trick was to just let it sit and warm up and then eventually the idle would smooth out and I'd be good.

When it didn't do it again I figured I was cool. A couple of weeks later though, this began to happen with every start (after the car had been sitting). It's only throwing a C15 code which is the coolant senso low temp indicator. I don't see why that would cause me a starting problem, but coincidentally the "check engine" light goes out when the idle smoothes.

Any ideas? What would you do to start pinning down the culprit. I searched threads but wasn't able to come up with anything.

 

If you access to a scan tool you can see the temp sensor readings. If its way off it can cause the type of problem you're having. Also check the wiring going to the sensor. Make sure its not shorting out anywhere.

 

EGR valve could cause these symptoms..

 

if im correct the temp sensor helps the fuel mixture, tells computer the what measurements of fuel and air to mix based on temp, if this dont work the car runs like crap until it warms up. hope this helps.

 

i just messed with these settings in my tune, the colder it is the richer it gets, the hotter it is the leaner it gets. try cleaning the conections at the sensor.

 

check fuel pressure...betcha she's dropping to below 10 psi while sleeping.

 

Your car may be having a problem with "open loop" mode, which should be activated before the car is warmed up. If the ecm is getting incorrect info from the cts, it might cause the problems you are having. there is a diagnostic tree chart in the FSM that could help.

 

I don't know the reason behind it, but I know from experience that the computer does not like it when it gets a reading from the coolant temp sensor that is way out of range.

The first thing I would check is that the connector is still attached to the sensor. Then you could ohm check the sensor - there's a page in the service manual that lists what the reading should be. Then start looking for a break in the wire or a bad connector.

 

Exactlty correct fix your temp sensor problem and it will be fine. I bet it is a broken connector or sensor it is hard to get that serpintine belt on or off without coming real close to that area.