Horrid idle - S-10 Forum
 
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post #1 of 15 Old 01-28-2016, 01:45 AM Thread Starter
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Horrid idle

I have a 1985 Chevy s10 the vin says 4 bangger but was swapped with a v6 2.8 I have a very rough idle and sometimes it's low sometimes not. Sometimes it will idle so low it will rumble and die none of the choke linkage really works so the choke is tied open and the idle cam dosent work properly so its tied to the h setting. When it comes completely off the idle cam it for sure idles so low it rumbles and dies. Sometimes it will stay on with out any throttle most the time I have to have throttle at least a little open.

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post #2 of 15 Old 01-28-2016, 04:13 AM
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It's probably related to your other threads
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post #3 of 15 Old 01-28-2016, 05:28 AM Thread Starter
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I have fixed the throttle valve cable for my transmission I'm jst wondering if the carb is out of time or if its a vacuum leak or what
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post #4 of 15 Old 01-28-2016, 09:03 AM
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Re: Horrid idle

There are a bunch of reasons for poor idle

1 Too rich - any black smoke at idle?
2. Too lean - exhaust smell sort of like turpentine?
3. Vacuum leak(s). Lots of different places for that to happen.
4. Idle speed screw (for throttle plates) set to low
5. Faulty EGR valve

The Rochester 2SE has a sealed idle mixture screw. It's located at the base of the carb toward the driver side front. You have to remove the plug to access it - which means removing the carb.
Once you remove the plug, you can adjust the mixture.

Turn the screw in = lean
Back the screw out = rich.

I suspect that backing the screw out a bit would solve your problem.

Many carbs have already had the plug removed. Check and see.

S10 addiction:
1)'82 S10, 383, 700R4, Shorty
2) '85 S10, 3.4, 700R4 4x4 stretch cab (Redneck)
3) '90 S10 2.5, 5 speed shorty
4) '91 S10, Built 3.4, 5 speed shorty (Voodoo)
5) '92 S10, 2.5, 5 speed shorty, (Barbie)
6) '92 S10, 2.5 5 speed, Shorty
7) 1979 LUV, Buick 3.8 V6, TH 350 Shorty.
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post #5 of 15 Old 01-28-2016, 04:57 PM Thread Starter
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Quote:
Originally Posted by Mad Max View Post
There are a bunch of reasons for poor idle

1 Too rich - any black smoke at idle?
2. Too lean - exhaust smell sort of like turpentine?
3. Vacuum leak(s). Lots of different places for that to happen.
4. Idle speed screw (for throttle plates) set to low
5. Faulty EGR valve

The Rochester 2SE has a sealed idle mixture screw. It's located at the base of the carb toward the driver side front. You have to remove the plug to access it - which means removing the carb.
Once you remove the plug, you can adjust the mixture.

Turn the screw in = lean
Back the screw out = rich.

I suspect that backing the screw out a bit would solve your problem.

Many carbs have already had the plug removed. Check and see.
I feel I'm running lean shakey idle smell unburned fuel I wanna check for a vac leak but I don't exactly know what hose to blow smoke in
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post #6 of 15 Old 01-29-2016, 10:45 AM
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Re: Horrid idle

You can use carb cleaner and spray it around the carb base and general area. If the idle changes, you know you have a leak.

Does this rig have A/C? If yes, there is a vacuum reservoir located by the driver headlight in the engine compartment. They have a tendency to crack causing a vacuum leak.

The power brake booster (although rare) can also rupture the diaphragm causing a vacuum leak. Disconnect the hose and plug it. No change = no problem.

The EGR has been known to be a problem too. Reach under the mushroom and push up on the diaphragm. If there is no change = no problem.

If this rig has a pre heat grid under the carb (carb gasket) GET RID OF IT!
These go bad after multiple years of driving and don't help performance at all. You can buy a replacement carb gasket without the heat grid in it. You may notice a small gain in performance too.

Hoses: the crap quality hose GM uses for vacuum routing is also problematic. They tend to rot over time and split. Usually the split occurs at the connection to any point in the vacuum system.

And... the ultimate solution?

W E B E R.

Everyone on the forum that has done this upgrade has had nothing but good results to talk about.

S10 addiction:
1)'82 S10, 383, 700R4, Shorty
2) '85 S10, 3.4, 700R4 4x4 stretch cab (Redneck)
3) '90 S10 2.5, 5 speed shorty
4) '91 S10, Built 3.4, 5 speed shorty (Voodoo)
5) '92 S10, 2.5, 5 speed shorty, (Barbie)
6) '92 S10, 2.5 5 speed, Shorty
7) 1979 LUV, Buick 3.8 V6, TH 350 Shorty.
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post #7 of 15 Old 01-30-2016, 02:21 AM Thread Starter
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I'll check vacuum when the weather clears up. And I would upgrade the carb if I had the significant funding
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post #8 of 15 Old 01-30-2016, 11:19 AM
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Re: Horrid idle

It's been a long time since I bought my '85 Blazer so memory may be bad. Seems to me the filter is in the carb. Mine was impossible to get out because the fitting was stuck tight. Who knows if it's ever been changed, or if the carb has been rebuilt or needs one. I didn't mess around with mine, but the Weber seems to be the way to go.

U.S.C.G. "Making sure the Navy doesn't get lost since 1790"

Apple Red 96 SS
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post #9 of 15 Old 01-30-2016, 11:20 AM
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Re: Horrid idle

Quote:
Originally Posted by TheSimpleStoner View Post
I'll check vacuum when the weather clears up. And I would upgrade the carb if I had the significant funding
Sometimes, biting the bullet up front is cheaper in the long run.

U.S.C.G. "Making sure the Navy doesn't get lost since 1790"

Apple Red 96 SS
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post #10 of 15 Old 01-30-2016, 11:59 AM
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Quit smoking weed? It's simple, stoner
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post #11 of 15 Old 01-30-2016, 05:20 PM
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Re: Horrid idle

Go weber and never go back.

I got mine on the bay for ~$200
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post #12 of 15 Old 01-30-2016, 08:28 PM
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Re: Horrid idle

+2 on the Weber! Just do it.
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post #13 of 15 Old 02-01-2016, 04:23 AM
Maybe later.
 
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Re: Horrid idle

The weber is the best.



I've had wayyy to many of these trucks. (Currently...on number 7)

1988 S-15 - 5.5/6 drop

1985 S10 Blazer 4WD

1998 Blazer ZR2 5 Speed!

Quote:
Originally Posted by fackinsteve View Post
3 doors for 1 and a half whores
Quote:
Originally Posted by svmcgover View Post
He only bought one wheel. So every picture we see is going to be a pic where either the rear or front is conveniently out of frame.

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post #14 of 15 Old 02-01-2016, 09:11 AM
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Re: Horrid idle

Man, this should be an advert for Weber...

S10 addiction:
1)'82 S10, 383, 700R4, Shorty
2) '85 S10, 3.4, 700R4 4x4 stretch cab (Redneck)
3) '90 S10 2.5, 5 speed shorty
4) '91 S10, Built 3.4, 5 speed shorty (Voodoo)
5) '92 S10, 2.5, 5 speed shorty, (Barbie)
6) '92 S10, 2.5 5 speed, Shorty
7) 1979 LUV, Buick 3.8 V6, TH 350 Shorty.
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post #15 of 15 Old 02-01-2016, 01:31 PM
Maybe later.
 
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Re: Horrid idle

Quote:
Originally Posted by Rhotpursuit View Post
It's been a long time since I bought my '85 Blazer so memory may be bad. Seems to me the filter is in the carb. Mine was impossible to get out because the fitting was stuck tight. Who knows if it's ever been changed, or if the carb has been rebuilt or needs one. I didn't mess around with mine, but the Weber seems to be the way to go.
Filter is in the carb on the rochesters. Yup.

Quote:
Originally Posted by Mad Max View Post
Man, this should be an advert for Weber...
Every 2.8 should have one!



I've had wayyy to many of these trucks. (Currently...on number 7)

1988 S-15 - 5.5/6 drop

1985 S10 Blazer 4WD

1998 Blazer ZR2 5 Speed!

Quote:
Originally Posted by fackinsteve View Post
3 doors for 1 and a half whores
Quote:
Originally Posted by svmcgover View Post
He only bought one wheel. So every picture we see is going to be a pic where either the rear or front is conveniently out of frame.

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