ok i'll give you a timeline of what happened.

1)put the car together, ran like a champ...took it to get dyno'd and tuned, everything turned out great.

2)replaced the thremostat because it was running an open loop and was keeping too cool.

3)everything was perfect, couldnt ask for a better running mustang at that time.

4)there was a pre existing condition on the car, whenever i would turn on the heat or headlights i could watch the volt meter drop a volt and not recover back to 12. so what i did was took off the starter solonoid to ground, battery to ground and cleaned up the connections because they were rusted and full of grime and crap.nowits all back together with clean connections. i changed NOTHING else.

5)i turned on the car and it idle'd like poop, ituse to idle between 850 to 1000 rpms. now its between 500 and 850 and it slightly vibrates when it tries to recover from the low idle. the volt meter looks great and doesnt drop so badly now when i turn stuff on....but when stuff ison now it sounds like it even has worse time staying alive.

so first thought was vaccume leak. i sprayed carb cleaner all over every vaccume line and all of the intake manifold., nothing there. so i'm totally missing something here!! give me some suggestions to check when i get home.


side question as well here. my temp gauge always hovered around 185-193*. today while i was driving it would be at 160* and then go up quickly to 205 and then shoot back down to 160 and then go up and hover around 190*. then it would go up to 205 and shoot back down to 160* and go up to 190* and hover again. my friend at work who owns 5.0 as well says thats totally normal and that his does it too. but i'veNEVER seen it do this before until now. is this normal? i thought the thermostat was supposed to slowly open and close to regulate temp, right?! so is this new thermostate broken?

**EDIT** its an aftermarket mechanical gauge

 

I don't know about the idling problem but did you burp your cooling system when you replaced your thermostat?

 

sorry forgot to add that. but i sure didburp the system left the rad cap off until it was warm and coolant filled theblock, then topped off rad.

 

bump

 

TTT

 

have i stumped you all? hehe j/k another bump bump it up!

 

Sounds like a pain in the ***. Have you checked your grounds good. If you think it is electrical i would get alt tested to rule that out. Take it to your local parts store.

 

alt is new...but im switching it out to a 3g this weekend, but i hopefully fix this issue before the swap. but its sounds like a charging issue so maybe it is a crappy alt.

 

How much have your driven it since the problem started, and if you have, has it gotten better? You disconnected the elctrical power, right? Maybe the computer needs to relearn?

 

If its idleing wierd you should check ur IAC to make sure its opperating corectly? could be somethin simple. What temp thermostat did u put it?