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high idle blazer


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4uz
User

Jan 1, 2012, 4:15 PM

Post #1 of 22 (3289 views)
high idle blazer Sign In

1988 chevy s-10 2.8 blazer 44,000 miles. put on a new iac vavle and tbi gasket .now it idles at 2000 rpm instead of the previous 1100. i think the iac is stuck (compressed ) how do i release the it to the regular lenth. i compressed it before i put in in. i don't know why.


Hammer Time
Ultimate Carjunky / Moderator
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Jan 1, 2012, 4:24 PM

Post #2 of 22 (3269 views)
Re: high idle blazer Sign In

If you compressed it before you put it in, you broke it. Go get another one and before you put it in, scrub out the throttle body, the back of the throttle place and the IAC seat with a brush and some carb cleaner.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 2, 2012, 4:22 PM

Post #3 of 22 (3232 views)
Re: high idle blazer Sign In

thanks for the quick reply. before i get a new one what do you think of this : monday i fixed the connections on the tube that comes from the left valve cover to the back bottom of the tbi unit. i put on the washer /gasket on the iac. ran the engine and idled around 2000 rpm. while it was running i disconected the wire from the plug/sensor that sits in the manifold in front of the tbi . to my suprise the idle went down to 1100 rpm . right where it's been the last 4 years. should i get anew one these also ?


Hammer Time
Ultimate Carjunky / Moderator
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Jan 2, 2012, 4:28 PM

Post #4 of 22 (3228 views)
Re: high idle blazer Sign In

Replace the IAC you broke first and if you still have a problem, then look into other things.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 3, 2012, 4:13 PM

Post #5 of 22 (3213 views)
Re: high idle blazer Sign In

i will post wensday to let you know whats doing.


4uz
User

Jan 4, 2012, 12:35 PM

Post #6 of 22 (3196 views)
Re: high idle blazer Sign In

it's wensday. i tryed the voltage test you suggested. i put the red lead on from meter to the white wire on map. and black wire on black wire on the map.. with throtle raised the voltage was higher. is this the right way to set the wires to do this test you didn't mention that. i switched them also and got a millivolt reading. it still idles at about 1400 rpm. when first starting blazer i have to feather the gas to keep it running (40 seconds to minute) then it stays at 1400 .is that the broke iac valve doing that ? i stuck two safty pins into the connector to test the voltage. i'll see what your reply is then i'll probally go buy another iac valve. it's 2:19 pm.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 4, 2012, 12:37 PM

Post #7 of 22 (3193 views)
Re: high idle blazer Sign In

I don't know what you are talking about. I never recommended any voltage test. I said to replace the broken IAC



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 5, 2012, 4:05 PM

Post #8 of 22 (3182 views)
Re: high idle blazer Sign In

sorry about the mix up . the other site , 2carpros . they suggested i do that test.which was to see if the voltage was higher at raised rpm than at low rpm .it was. any way tommorow i think i'll get a new iac. which ever i do i'll let you know on friday.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 5, 2012, 4:19 PM

Post #9 of 22 (3179 views)
Re: high idle blazer Sign In

Yeah, that was Rivermikerat. Ignore that. The MAP isn't causing the high idle.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 6, 2012, 4:11 PM

Post #10 of 22 (3168 views)
Re: high idle blazer Sign In

tryed a little test today (friday).i had a pintle from the origanal iac. i cut the shaft of it to a half inch long. stuck it in a hole i drilled in a wooden dowel. put that in a brass fitting that just barely gripped when screwed into the iac inlet. sealed it .pushed the dowel in until it seated inside. started engine had to hold rpm to keep it from stalling. the backed it out until when i started it again it would idle. i backed it out and got engine to idle at 1000 rpm. soo i'm going to get another iac saturday. i should have it in by noon tommorow. i'll surley post the results. it's 5:53 pm here in trenton . i'll check this post before i go offline tonight incase you have any thing else. i'll install it as is right out box.


4uz
User

Jan 7, 2012, 3:00 PM

Post #11 of 22 (3157 views)
Re: high idle blazer Sign In

saturday: put in new iac started .idled at 3000rpm for one minute. shut off engine sterted again it went down to 1400 rpm. took it for a ride up to 40 mph to like the instruction s said. back in driveway the idle is at 13 -1400 jus the same as the previous iac that you said i had broken by pushng in spring. something is not setting the pintle in far enough to lower the idle. there has to be a fix for this .other than that it runs and accelerates really well . i'll check back to this post later tonight just incase you answered.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 7, 2012, 3:40 PM

Post #12 of 22 (3155 views)
Re: high idle blazer Sign In

The system has to be pulling unmetered air in from somewhere other than the IAC. You really need a scan tool to monitor the IAC count and see if the computer is trying to make it lower or not.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 8, 2012, 6:40 AM

Post #13 of 22 (3143 views)
Re: high idle blazer Sign In

is there a place i can rent a scan tool ? and since the neww iac didn't make a difference should i take it back to advanced auto for a refund ?


4uz
User

Jan 8, 2012, 4:04 PM

Post #14 of 22 (3134 views)
Re: high idle blazer Sign In

sunday :you say there must be an air leak.what do you think of this,i made a manual iac vavle that is air tight. i screwed it all the way in to seat it in the tb. i started the engine cold. i kept my foot on gas pedal having it warm up at 2000 rpm for one minute.took foot of pedal and it died out. i manualy then backed out the manual iac. started engine and it was at about 1500 rpm then i backed it out untill it got down to 800 rpm. it idled just fine.the wiring clip that goes into the proper iac is just hanging loose. if i had a vacum leak like you said would't this prove that to be wrong ? because when the homemade valve is screwed all the way in the engine dies.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 8, 2012, 4:07 PM

Post #15 of 22 (3132 views)
Re: high idle blazer Sign In

That pretty much proves the IAC is causing the problem, whether it's being told to or not still needs to be determined with a scan tool.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



way2old
Veteran / Moderator
way2old profile image

Jan 8, 2012, 5:13 PM

Post #16 of 22 (3128 views)
Re: high idle blazer Sign In

Which throttle body gasket did you replace? Was it the base gasket or the intermediate gasket? If you replaced the base gasket, look closely in the throttle body to see if you see any gasket material being sucked into the throttle body.



Being way2old is why I need help from younger minds


4uz
User

Jan 9, 2012, 4:09 PM

Post #17 of 22 (3117 views)
Re: high idle blazer Sign In

to hammertime :i'm going to check around for the scan tool use. i'll post again . to way2old:i removed 3 bolts from the top of TB so it must be the intermediat gasket. i'll look in the tb and let you know tommorow.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 9, 2012, 4:12 PM

Post #18 of 22 (3114 views)
Re: high idle blazer Sign In

What Way2old suggested is a common problem but I think you have already eliminated that possibility when you were able to make it stall by blocking off the IAC.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 10, 2012, 12:38 PM

Post #19 of 22 (3106 views)
Re: high idle blazer Sign In

your right. here one. the temp gauge on dashboard is reading just on or slighty above the 100 degr. mark. the engine isn't going up to high enough temp because the thermostat is not closing so the computer thinks the engine is still cold and keeps the rpm up around 1400 rpm. or is there a temp sensor somewhere that is not working right ? i'll be online this evening in cse you respond to this post. maybe replace thermostat. went to local gas station where they give free scan tool checks but his tool is for obd2 systems and mine is obd1 system.it gives codes by turning key to on and jumping the A B terminal on the thing under the drier side dash. mine does not display or blink anything. on other post i read it means that either the ECM is bad or somthing else.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 10, 2012, 1:57 PM

Post #20 of 22 (3101 views)
Re: high idle blazer Sign In

You need to use a scan tool to look at sensor temperatures as the computer sees them. It could be a sensor problem.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



4uz
User

Jan 10, 2012, 5:05 PM

Post #21 of 22 (3091 views)
Re: high idle blazer Sign In

i have obd1 . codes are retreived by reading flashes on the dashboard lights. if there is a scan tool could you tell me where to get one. again when i jumped the a and b terminal i got no flashes. whick according to some means the ecm or something is not working.


4uz
User

Jan 13, 2012, 3:33 PM

Post #22 of 22 (3065 views)
Re: high idle blazer Sign In

is there any where i can get a scan tool ?






 
 
 






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