Hi I don't know if this post is in the right place cuz I new to this Blazer forum.

I own a 2000 Chevy S-10 Blazer lt 2wd 4.3l v6 and I have had a problem with it lately, it has a really high rpm count on a cold start-up. When I do a cold start the rpm's shoot up to somewhere between 2000-3000 rpm's and sits there for about 2-3 seconds then slowly come back down to the normal cold rpm's around 1000.

The tech I took it to replaced the IAC and did a timing adjustment and nothing done has helped and the tech doesn't know what else to do so I'm stumped. So any help would be awesome because I love this vehicle and I want to fix this problem.

It also has a shaking idle along with the 2000-3000 rpm cold starts.

 

Sounds like it may be a vaccum leak issue. Does it do it any time when warm?

 

Nope only when the engine is cold.

 

If it was vacume leak it would idle high and irrectacaly all the time.I would check your throttle position sensor.
My truck is a 94 with 4.3 tbi and when its cold it will idle high for a couple minutes before it drops down to normal.

 

How would I test it? Do I unplug it and see if that helps?

 

[QUOTE=lockwoodjace;564204]How would I test it? Do I unplug it and see if that helps?

I few different ways I know that are simple.It should throw code 35 I think but not always.You can unplug and if you notice no difference then its bad.Another way is to test how much voltage or ohms its running.Im not the greatest with electrical things ask Capatain Hook he can explain better than I can.The man is a wizard when it comes to these sort of things.
Its strange 6 years difference in the make of our vehicle 2 different type of injection systems but yet we experience the same symptoms.The shaking at high idel feels like the choke is sticking it will do this for a short amount of time maybe a minute or two depending on how cold it is.

 

Well I unplugged it and it made a small difference with the throttle position sensor unplugged, so I don't think it is that and I don't think its a vacuum leak, so any other thoughts on what it could be???

 

Write to Capatain Hook and ask him he will probaly know.Hes a wizzard when its comes to electronic parts sensors and such.Im not familair with all the sensors on the later models.Maybe do a google search on all related sensors that affect the idle on your engine.

 

When they replaced the IAC valve, did they clean the bore that it goes into? If not, if could be getting hung up in the bore. I would remove the throttle body & give it a good cleaning.

And please do not recommend PM'ing members for tech help. Please keep it in the open forums. Those of us that can help will respond when we have a spare moment.

 

Have checked the map sensor?You can try taking that out and cleaning carefully with special cleaning fluid.Also I did not mean PM the member i mentioned ask him openly.Sorry I didnt clarify that.