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96 mazda B3000 pick up, revs at 3500 apon starting


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bigdaddycools
New User

Aug 29, 2011, 12:59 PM

Post #1 of 9 (4260 views)
96 mazda B3000 pick up, revs at 3500 apon starting Sign In

Hi I have a 96 maz B3000 pickup 6 cylinder aprox 185 km on it. This problem started about 8 months ago, started truck after stopping at a store and it reved out at 3000 rpm rite off the hop! I gave the throtle a boot made things worse by about 200rpm. Got under hood and disconected the Idle Air Control Valve and RPM's dropped so low, I had to two footer on the way home. I put a brand new IACV on and it seem to fix the problem....Now 8 months down the line its doing it again....so I get an other brand new IACV thinking the other may be defective....It did not make any diffrence I start my truck and its at 3000rpm's...can anyone make sence of this problem?....I have checked for vacum lines that might be off...every thing seems in place... any help would be greatly apreicated!!!!!Crazy


Hammer Time
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Aug 29, 2011, 1:39 PM

Post #2 of 9 (4253 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

Try cleaning the inside of the throttle body and throttle place with carb cleaner. Also make sure there are no air leaks anywhere.



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Discretesignals
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Aug 29, 2011, 5:53 PM

Post #3 of 9 (4241 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

I don't mean this in a disrespecting way to you Hammer, but you really don't want to clean the throttle body on that one with carb cleaner or anything harsh like that. They put a Teflon coating inside the throttle bore and you don't want to take that off. If you take it off, the TB will get grimy faster which could possibly affect the idle speed.

Normally unplugging the IAC causes the engine to stall out if you don't have any vacuum leaks or a stuck open IAC. If unplugging the IAC caused the engine to idle really low or even stall, that would mean the IAC isn't the cause for the high idle. More than likely that would mean the ECM is commanding the idle speed that high and you need to figure out why. You would need a scan tool to monitor sensor inputs that would cause the ECM to up the idle speed. Some inputs I can think of are power steering switch, trans range, air conditioning request, and possibly engine coolant temperature input.





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(This post was edited by Discretesignals on Aug 29, 2011, 5:56 PM)


Hammer Time
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Aug 29, 2011, 6:00 PM

Post #4 of 9 (4232 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

Yeah, I'm aware of the coating they put on all the Fords and I think it's worthless. I've always gone ahead and cleaned them with good results. The cleaning was meant to get the inside of the IAC too. I told him to find the air leaks first.



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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.



Discretesignals
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Aug 29, 2011, 6:08 PM

Post #5 of 9 (4228 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

I think the Teflon coating is worthless too. I usually clean them with WD-40, but now I am hearing that WD-40 has silicone in it that can wreck O2 sensors.

You would think if it was a vacuum leak causing it unplugging the IAC wouldn't cause the engine to stall or run at an extremely low idle speed. I always used to get that backwards, but after seeing so much of that it straightened me out.





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Hammer Time
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Aug 29, 2011, 6:15 PM

Post #6 of 9 (4224 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

All it needs is unmetered air to raise the idle.



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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.



Discretesignals
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Aug 29, 2011, 6:23 PM

Post #7 of 9 (4220 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

True, but the ECM can compensate for some small leaks by closing the IAC some. If you see that your IAC counts have the IAC slammed shut, then I would be looking for a vacuum leak, a stuck open IAC valve, or stuck throttle plate.

It would have to be a very big vacuum leak to cause the engine to idle that high (3500). If the leak was that large, unplugging the IAC wouldn't affect the rpm, but the OP stated that by unplugging the IAC the engine rpm went really low.

Vacuum leak that large would probably also set some lean codes.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Aug 29, 2011, 6:23 PM)


Hammer Time
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Aug 29, 2011, 6:26 PM

Post #8 of 9 (4214 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

He didn't post mileage. Throttle body could be wasted too.



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

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.



Discretesignals
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Aug 29, 2011, 6:33 PM

Post #9 of 9 (4209 views)
Re: 96 mazda B3000 pick up, revs at 3500 apon starting Sign In

Could be. Throttle shaft worn out or binding causing throttle to stay partially open. He did state that jabbing the gas pedal cause the idle to go even higher. Carpet jamming gas pedal scenario. Could even be a faulty TPS showing a higher voltage than it should.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Aug 29, 2011, 6:34 PM)






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