Stall when turning the wheel at idle and poor idle

Tiny
JOSH71411
  • MEMBER
  • CHEVROLET SILVERADO
I have a 1993 chevrolet silverado with a 4.3l v6 vin code "z" the mileage is 198,789 if my truck is idling


http://www.2carpros.com/forum/automotive_pictures/102442_IM000223_1.jpg

with the a/c on and in gear and i turn the wheel my truck wants to stall it doesnt die but almost does then the rpms will pick back up until the wheel is turned again i have tried everything i think if anyone has some help i would really appreciate it
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Tuesday, September 25th, 2007 AT 6:06 PM

15 Replies

Tiny
BMRFIXIT
  • EXPERT
The rpm drop not being compensated for by the idle air control
check it and check the air way for it make sure its clean and free of carbon
good luck
let us know
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Tuesday, September 25th, 2007 AT 10:16 PM
Tiny
JOSH71411
  • MEMBER
I have already replace the idle air control valve and no improvement
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Wednesday, September 26th, 2007 AT 4:09 PM
Tiny
DENNYP
  • EXPERT
Try cleaning the throttle body and spraying a good carbon cleaner in the throttle body with the enging running. I would recommend "sea foam" or "GM top engine cleaner".
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Thursday, September 27th, 2007 AT 11:05 PM
Tiny
JOSH71411
  • MEMBER
I have already cleaned the throttle body for about an hour still no improvement any more suggestions
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Friday, September 28th, 2007 AT 5:36 PM
Tiny
JOSH71411
  • MEMBER
I seriously need help on this problem its driving me crazy I dont know what it is I think I have replaced just about everything it only wants to drop idle when the wheel is turned with the air on and in gear if truck is in park its not as bad but still stalls when the wheel is turned so I dont think it is a torque converter problem I have replaced the idle air control valve so I think it maybe a power steering pump of steering gear please help !
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Sunday, October 14th, 2007 AT 11:43 AM
Tiny
BMRFIXIT
  • EXPERT
Let s start fresh
Running ok steering fine put AC on wants to stalls when steering
Rpm ok @ idle and in drive engine running strong
AC on wants to stall when turning
Here what I m thinking?
Check the AC pressure hi side

Good luck
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Monday, October 15th, 2007 AT 6:05 PM
Tiny
JOSH71411
  • MEMBER
Ok so I need to ask a few questions before I do this I believe u know something I dont but what would the high side have to do with the problem and how would I check the high side I have a set of manifold gauges but im new at a/c and also what would I be looking for
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Monday, October 15th, 2007 AT 8:43 PM
Tiny
BMRFIXIT
  • EXPERT
You did just about every thing else
Just another idea
hook the gauges up and read the high and the low side s
If the high is too high that may be putting drag on the engine
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Tuesday, October 16th, 2007 AT 5:40 PM
Tiny
JOSH71411
  • MEMBER
What should the high side pressure be
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Wednesday, October 17th, 2007 AT 8:22 AM
Tiny
BMRFIXIT
  • EXPERT
I don t have the spec on that but I would say no more than 260
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Wednesday, October 17th, 2007 AT 8:24 PM
Tiny
BMRFIXIT
  • EXPERT
Thank you fisherman
Another carpros tech
He came with this
hope that can help

(the IAC valve its not adjusted right! The ECU should take care of the "load" of the A/C and power steering!

Here a text about IAC Valve:

Basically, as we already know, the IACV regulates idle speed, raising and lowering it as needed. It does this by opening and closing a "trim" valve to allow more or less airflow into the intake manifold when the throttle is closed.

The adjustment we make on the IACV is for setting the "base idle". By unplugging the TPS (and the IACV in some cases) we tell the ECU to completely close the trim valve in the IACV. When this happens, the idle airflow comes completely from a needle valve - the very one we are adjusting when we turn the screw on the IACV body.

If everything in the fuel and intake system is operating properly, the idle speed will not be able to drop below this setting. A few things can cause the base idle speed to go out of adjustment.

First, the needle valve can become clogged with dirt or carbon, reducing or completely blocking off airflow through the needle valve. This would reduce the airflow through the needle valve and cause the ECU to rely partially or fully on the opening of the trim valve in the IACV to maintain target idle. This would mean that the idle could possibly fall below 750 before the ECU could intervene.

Second, the trim valve within the IACV could be rendered partially or totally inoperable, either through blockage or failure. If this valve is blocked open, idle speed would be high unless the needle valve's opening was reduced to compensate. The result of this may be the inability for the ECU to compensate for all idle conditions - base idle would be set for Y percent trim valve opening, leaving only X-Y percent of the operating range of the trim valve for ECU adjustment. If the trim valve is not blocked open but the passage to this valve is partially clogged, it would require the ECU to open the valve farther than normal to allow a given amount of airflow to pass. This would also reduce the amount of compensation the ECU can apply to idle speed.

To sum it up, there are two idle speed adjustments to control idle on our cars. First is the manually adjusted base idle setting, which determines the minimum airflow through the IACV (and minimum warm-idle speed). Second is the ECU's control over the "trim" valve within the IACV, which compensates for hot and cold idle and engine loading (power steering and A/C operation).
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Wednesday, October 17th, 2007 AT 8:40 PM
Tiny
JOSH71411
  • MEMBER
Ok well I see I need to get a different iac I bought an idle air control valve from oreillys that has only been in the truck a few weeks but right after I put it in there were still no improvements what name brand iac should I get and again tell me how to set it once I get one also I want to tell u exactly what its doing. In the morning or after the truck has been sitting a while I go to crank it up and it does not idle rough as long as the motors cool even if the air is on and its in gear and you turn the wheels there is no stuble and no rough idle once the motor heats up to normal operating temp the truck starts to idle rough sitting still at a light and if u slightly turn the wheel the idle drops and the truck trys to stall and shakes real bad then after the idle drops it will surge up and then back down to a rough idle it also makes the motor feel like it is missing but its not a miss because I have changed all of the igniton components so thats exactly what it does its the most aggrivating problem I have ever run across please reply back
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Thursday, October 18th, 2007 AT 4:05 PM
Tiny
BMRFIXIT
  • EXPERT


http://www.2carpros.com/forum/automotive_pictures/99387_silverado1_1.jpg

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Thursday, October 18th, 2007 AT 7:16 PM
Tiny
JOSH71411
  • MEMBER
I appreciate the pic but I kinda cant see it all is there anyway for me to see the other half thanks
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Thursday, October 18th, 2007 AT 10:39 PM
Tiny
JOSH71411
  • MEMBER
Good news I fixed the missing problem and most of the stalling problem when the wheel is turned I took the iac out which was factory preset and screwed the valve in which immediately fixed the problem when I started it back up and let it warm up but I still have the steering problem but I think it is in the actual power steering here is what it does if your in park with air on and u turn the wheel without foot on the brake its usually fine if its in gear its usually also fine but if the brake is applied and u turn the wheel the wheel wants to lock and u have to let off of the brake for it to unlock but the power steering is NOT in full lock position therefore I have reason to believe it might be the power steering pump getting weak or the steering gear locking up when the wheel is turned but I dont see what that has to do with the brakes thanks for helping fix one problem just one more left =)
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Thursday, October 18th, 2007 AT 11:12 PM

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