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10-05-2014, 06:55 PM
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#1 |
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Registered User
Join Date: Aug 2014
Location: Arlington, Washington
Posts: 7
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Erratic idle
I have a 1990 GMC Sierra 1500 5.7 2wd. When i have the timing advance unplugged my run as great. But when i plug it back in my truck barely runs. Had trouble keeping idle.. Anyone know what could be causing this?
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10-06-2014, 07:04 PM
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#2 |
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Registered User
Join Date: Aug 2014
Location: Arlington, Washington
Posts: 7
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Re: Erratic idle
If anyone can help i would greatly appreciate it.
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10-06-2014, 09:09 PM
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#3 |
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Registered User
Join Date: Apr 2013
Location: GUNTERSVILLE
Posts: 621
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Re: Erratic idle
I have been chasing a similar issue with mine for a while and I can tell you no one can say with any certainty what the problem is. It is probably safe to say some sensor(s) is giving the computer some bad information and causing the computer to change setting. But the issue is which one? It's going to take some diagnosis.
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10-06-2014, 09:12 PM
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#4 |
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Registered User
Join Date: Aug 2014
Location: Arlington, Washington
Posts: 7
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Re: Erratic idle
Thanks. Im gonna try to change out my knock sensor and see if that works i will keep you updated. Thanks again.
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10-06-2014, 09:22 PM
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#5 |
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Registered User
Join Date: Apr 2013
Location: GUNTERSVILLE
Posts: 621
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Re: Erratic idle
Unless you have reason to think any sensor is bad, your probably going to waste a lot of money replacing good sensors. If you search the internet for rough idle issues you will lots and the few that cured there, all have different solutions. You can find lots of examples of people throwing parts at a problem and still not fixing it. That is why I say diagnosis is important.
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10-07-2014, 12:09 AM
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#6 |
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Registered User
Join Date: Aug 2014
Location: Arlington, Washington
Posts: 7
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Re: Erratic idle
Okay thanks. Im gonna look into it a little further.
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10-08-2014, 10:59 PM
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#7 |
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Registered User
Join Date: Oct 2014
Location: Hemet, CA
Posts: 129
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Re: Erratic idle
I've had a similar problem with my 91 but it's a 4.3, it would idle like crap and almost die at stoplights. I replaced most of the sensors and did a full tune up with no results. Then it finally died one day at a stoplight, then again while driving. I ended up completely disassembling the throttle body and cleaning all parts of it with carb cleaner and reassembled with a new gasket kit, some of the passages inside of it were almost completely clogged with carbon. Once it was all said and done it idled like a whole different truck.
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10-09-2014, 12:43 PM
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#8 |
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Registered User
Join Date: Apr 2013
Location: GUNTERSVILLE
Posts: 621
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Re: Erratic idle
That is one suggestion I have not hear before and it makes a lot of sense too.
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10-12-2014, 12:34 PM
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#9 |
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Registered User
Join Date: Aug 2014
Location: Arlington, Washington
Posts: 7
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Re: Erratic idle
Im gonna try that thanks 91short.
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10-13-2014, 10:13 PM
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#10 | |
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Registered User
Join Date: Dec 2013
Location: Addison TX
Posts: 142
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Re: Erratic idle
Quote:
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10-14-2014, 11:38 AM
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#11 |
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Who Me?
Join Date: Sep 2010
Location: Royal Palm Beach, FL
Posts: 4,065
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Re: Erratic idle
If it has an Idle Air Control valve, change that.
__________________
 Steve1997 Tahoe LT 4D 2WD (DD) 1961 Apache 10 (sold) 1965 C10 Stepper (sold) |
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10-14-2014, 07:24 PM
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#12 |
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Who Me?
Join Date: Sep 2010
Location: Royal Palm Beach, FL
Posts: 4,065
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Re: Erratic idle
RockAuto.com shows this for your '90 with a 5.7 ACDELCO Part # 217437.
I had some idle issues with my 97 and that solved it! Hope that helps.
__________________
Steve1997 Tahoe LT 4D 2WD (DD) 1961 Apache 10 (sold) 1965 C10 Stepper (sold) |
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