idle surge/low coolant temp

[streetmasters]

I appreciate any help I can get! I have done some searches and have a good idea of what is goin on with my car but just wanna b sure

Ok so when the car is warming up In the morning it sometimes does not reach operating temp. When and if it does reach normal operating temp, the idle stays high at 1300-1400 rpm. This is at 20 degrees outside. When I start rolling down my driveway the idle starts surging up to 1700 then down to 1100 over and over until the car comes to a stop.

As I drive I notice also that my car does not want to heat up after driving it for 20-30 min. Sometimes when it does heat up to normal operating temp it will go back down to being cooler again after a few min.

Also,If I am driving in first gear and the rpm falls below 2000 rpm the car will start bucking- all while being in gear... Then if I push in the clutch to avoid the bucking the idle surge starts again.

I have seen posts about the idle surge but thought that my problem may be related to the coolant temp problems I am seeing.

Again, any help will be awesome! /ubbthreads/images/graemlins/smile.gif

 

[atc250r]

Put a new t-stat in it and get back to us. I'd put money on it that the problem is the stat. I run a 180* stat in mine.

John

 

[streetmasters]

Ill def get on that... Today the car is warming up fine but the idle surge is still crazy.. Now its doing it at idle.. Could the t-stat be related to the surging too??

 

[atc250r]

Yeah, definitely. If you're going by the stock gauge in the instrument cluster you're wasting your time. That thing will read in the middle anywhere from 130* to 210* so you really can't base any diagnosis at all off of it. Toss a decent (Stant) stat in the car and see what happens.

John

 

[cbr900turbo]

To check your temp if you have an infrared heat gun they work great, also you may want to pressure test the cap while your at it and maybe replace it if its old. The idle could also be a vacuum leak of some sort.

 

[streetmasters]

Thx a lot! I will get on that asap /ubbthreads/images/graemlins/smile.gif

 

[streetmasters]

Ok took a while but I finally changed the t-stat. I still have the crazy idle surge- what would be the next easiest thing to check?

I have seen some posts about boost leaks etc. but I want to start with the most obvious and easiest troubleshooting...

Any help would be awesome!!

 

[GVR4_1057]

The other culprits could be. Bad ISC, leaky TB shaft seals, bad injector seals,bad intake manifold gasket. Pretty much anything that lets air into your engine on the intake manifold side of your throttlebody. This is where a pressure test is a big help to show you the leaks.

I am assuming also that you still have the coolant lines hooked to your throttlebody.

 

[streetmasters]

ok cool ill try a pressure test and see what happens...thanks for the info!!