erratic RPMs on 94 mazda b3000 - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 10-22-2011
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Icon6 erratic RPMs on 94 mazda b3000

I have a 94 mazda b3000 over 150k miles. 2 weeks ago when i started the truck my RPMs started going crazy. It would idle at 2k RPMs then shoot up to 3k and sometimes a bit more then drop, then rise all the way up again. It seamed to drop slightly when i pushed in the clutch. The check engine light will only stay on for about 5-10 sec after i push the clutch then it goes off.

First i replaced the IAC valve and that did nothing. I searched everywhere for any leaks and couldnt find any. Next I threw some sea foam in and that took care of about 70% of the problem. So I went and bought a new TP sensor. The truck now idles at about 1200 to 1500 RPMs and if i push in the clutch it drops very low..almost to 500. light still comes on for a few sec when clutch is depressed.

Its now drivable but what else can i do to get it back to idleing arround 1k and not have the RPMs drop to the point of almost stalling if i push in the clutch?
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Old 10-23-2011
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check the MAF/MAP sensor...not sure which on a 94 has
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Old 10-23-2011
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Thanks I will check.
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Old 10-23-2011
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Why are you buying parts blindly rather than diagnosing the actual cause of the problem before buying anything? To solve the problem once and for all and be done with it, you need to first visually inspect for obvious problems and distress, then pull the DTC's, then follow the diagnostic troubleshooting charts to systematically identify the problem, and if needed, do a pinpoint diagnostic on a suspect part and then replace it once it's proven to be bad. So much cheaper, time saving, and lowers frustrations by following protocol on repairing engine management system issues rather than guessing or using the "spray and prey" method (ie, throw parts at it and hope for the better).

*Have you sprayed starting fluid around the intake to head interface when it's acting up, and if so, what happened? Suppose for a moment you have a leaky intake gasket. You can spend all sorts of time and money by blindly throwing sensors at it, and you'll never find and fix the actual problem until you diagnose it. Auto parts store will make a killing selling you parts you never needed. Just a little food for thought is all.
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Old 10-23-2011
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MAF is good.
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Old 10-23-2011
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well so far after it sits for a bot the rpms drop to 900. but now when i put it in neutral when im comming to a stop or when i stop it shoots up..then its fine while driving. Also im getting surges of power while driving towards time to shift. any other ideas b4 i just drop it off at a mechanic and eat it?
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Old 10-24-2011
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Quote:
Originally Posted by Seamair View Post
well so far after it sits for a bot the rpms drop to 900. but now when i put it in neutral when im comming to a stop or when i stop it shoots up..then its fine while driving. Also im getting surges of power while driving towards time to shift. any other ideas b4 i just drop it off at a mechanic and eat it?

Quote:
Originally Posted by CowboyBilly9Mile View Post
Why are you buying parts blindly rather than diagnosing the actual cause of the problem before buying anything? To solve the problem once and for all and be done with it, you need to first visually inspect for obvious problems and distress, then pull the DTC's, then follow the diagnostic troubleshooting charts to systematically identify the problem, and if needed, do a pinpoint diagnostic on a suspect part and then replace it once it's proven to be bad. So much cheaper, time saving, and lowers frustrations by following protocol on repairing engine management system issues rather than guessing or using the "spray and prey" method (ie, throw parts at it and hope for the better).

*Have you sprayed starting fluid around the intake to head interface when it's acting up, and if so, what happened? Suppose for a moment you have a leaky intake gasket. You can spend all sorts of time and money by blindly throwing sensors at it, and you'll never find and fix the actual problem until you diagnose it. Auto parts store will make a killing selling you parts you never needed. Just a little food for thought is all.

Last call, do it yourself the same way a pro would or just drop it off at a reputable shop and have an experienced, competent mechanic do this exact same thing and present you with the bill when it's done. Careful what shop you go to, you want them to do it right rather than throw parts at it hoping for the better and billing you for each and every one of them, including the ones that weren't even bad because they didn't know how to diagnose the problem, of which many shops like to do and consumers know no better other than it's fixed.

Last edited by CowboyBilly9Mile; 10-24-2011 at 02:58 PM.
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