96 305 RPM's ramp up

[Buroaktree]

Greetings
1996 Sierra, 85000 miles, 305 starts fine cold, idles at 900, but when I put her in gear, she ramps up to 1100 - 1200 rpm, and wants to run away like a scalded monkey til 5 mins or so later after warming, then idles calms down to 650.
Doesn't do this if started warm but will after sitting for several hours.
I hope it's no biggy but it wastes gas and I wonder since it's doing this in hot weather, what will it do in the winter?
Thanks
Dave

[03chevy]

welcome to the forum.. you can check this out

3Inspect Choke Pulloff Worn, defective, or faulty choke pulloff(s).

4Inspect Hood Brace Leaking, worn, or damaged intake manifold gasket

5Inspect Choke Thermostat Stuck or improperly functioning choke thermostat.

6Inspect Carburetor/Fuel Injection Gsk Deteriorated, or faulty carburetor/throttle valve mounting gasket.

7Inspect EGR Valve Clogged, dirty or improperly functioning or defective egr valve.

8Inspect Idle Air Control Valve Damaged, loose, or faulty idle air control valve.

9Inspect Idle Speed Control Actuator Damaged, loose, or faulty idle speed actuator.

10Inspect Idle Stop Solenoid Damaged, loose, or faulty idle stop solenoid.

11Inspect Throttle Position Sensor Faulty throttle position sensor or throttle position sensor circuit.

[mudseeker]

i'm guessing either IAC valve stuck open or vacum leak at the intake. leaning more toward the intake leak though.

[Buroaktree]

thanks,
looks like I need to get her on the diagnostic, but first save a few bucks
since an intake leak/gasket will cost...

[Buroaktree]

well...dealership wants $670 to change upper/lower intake gaskets including thermostat & oil change. Strange that there were no codes so if theres a leak, it must be small.
wish I had the knowledge to do the job but it took me a day to get the plugs/wires/cap/rotor replaced!
thanks guys for your help
Dave

[brad4eva]

you are crazier then idk what to pay 670 $ for that!!! go pay 30 $ for a book and learn!

[Buroaktree]

thanks (I think) I bought Haynes book but it doesn't tell me step by step how to do this job plus I don't have a torque wrench or torch if the bolts are froze.
I quess we can't all be experts can we.

[brad4eva]

Borrow one from O reillys or auto zone.. well
1. Write down all of the vaccums etc where they all go
2. Drian as much as antifreeze as you can out of the top of the motor
3. Take your radiator hose off
4. Take your air breather off start unpluging vaccums unplug your injectors and all that
5. get a 9/16 take off your TBI, (put a rag down in your holes so nothing falls down in there
6. Take your distrib out *unplug all wires*
7. look down in your intake where your radiator hose goes n thermast you should be able 2 see just inside of your itake , if u see anti freese try some way to drain as much as possible out so you wont have to replace oil.
8.start unbolting all the bolts on both sides of intake should be like 10-12 not real sure
9. should beable to take a screw driver and pry it open and there you go your intakes off
10. clean it real good if you got clumps of old oil sagged up clean all that good get some sand paper and clean the intake edges n **** like that get some silcone and put a bit on the front and back
11 put your intake gaskets on and start following these steps backwards


just some tips

[mudseeker]

Originally Posted by brad4eva

Borrow one from O reillys or auto zone.. well
1. Write down all of the vaccums etc where they all go
2. Drian as much as antifreeze as you can out of the top of the motor
3. Take your radiator hose off
4. Take your air breather off start unpluging vaccums unplug your injectors and all that
5. get a 9/16 take off your TBI, (put a rag down in your holes so nothing falls down in there
6. Take your distrib out *unplug all wires*
7. look down in your intake where your radiator hose goes n thermast you should be able 2 see just inside of your itake , if u see anti freese try some way to drain as much as possible out so you wont have to replace oil.
8.start unbolting all the bolts on both sides of intake should be like 10-12 not real sure
9. should beable to take a screw driver and pry it open and there you go your intakes off
10. clean it real good if you got clumps of old oil sagged up clean all that good get some sand paper and clean the intake edges n **** like that get some silcone and put a bit on the front and back
11 put your intake gaskets on and start following these steps backwards


just some tips

'96 is CSFI and has a 2 piece intake, it's not as simple as the old TBI units.........

[Buroaktree]

thanks
I appreciate the tips
DAve