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Fast Rough Idle Issue after Fuel System Reassembly

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#1
Greg Kimble

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Looking for some advice, we just got done reassembling the intake side of our motor after removing the fuel injectors and having them serviced, also at our last race the egr pipe that runs behind the head broke and replaced that, in order to access the egr pipe we removed the coils to gain access, while everything was apart, we also cleaned the throttle body and intake manifold with some carb and choke cleaner. Now that its all back together, it fires right up but it idles at abour 2200 rpm on the factory tach (about double the normal reading), after warming up for a minute or two the motor starts to rev to about 2200 rpm and then suddenly drops to 1900 rpm then back to 2200 and cycles from 2200 down to 1900 as long as you let it run.

I am only aware of one ground on the intake side that bolts to the intake manifold near the egr valve, everything else looks ok, the manifold was torqued from the center out with a new gasket, all vaccuum lines and wiring harnesses look ok. The check engine light never came on.

Any ideas are appreciated

Greg
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#2
seege

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MAF disconnected?
CJ Johnson

#3
Dave Lewis

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If you used carb cleaner you probably removed the seal on the butterfly.

#4
Ron Alan

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If you used carb cleaner you probably removed the seal on the butterfly.



Ah-hah! After reassemble for a new head we've had the same hi idle issue. Not this hi but definitely different than it was. I used carb/brake cleaner on the intake also. Maybe not such a good idea???

Ron

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#5
Greg Kimble

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Ok, I think the seal on the butterfly is now gone, upon inspection there is nothing but metal on metal and looks like there is a small gap around the butterfly. After a check of the Mazdaspeed website, it looks like the butterfly or seal is not available by itself, can anyone confirm this? Then it looks like the solution is a replacement throttle body?

Greg
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#6
Greg Kimble

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To bring closure to this post, I purchased a used throttle body, bolted it on and it idles nice n smooth now . Lesson to be learned, dont go crazy with the carb cleaner.

Greg
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#7
Scott Malbon

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I've had the same problem and replaced multiple sensors and vacuum hoses chasing it. I didn't know the butterfly had a seal. I'll check mine now. But does it matter on the race track when we are WOT?

Scott




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