Possible fix for low idle/ vibration at idle when hot - RX8Club.com



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Old 06-08-2009, 09:50 PM   #1
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Thumbs up Possible fix for low idle/ vibration at idle when hot

For those that have vibration at idle or idle problems, most of you probaly checked/replaced all the usual stuff like coils/spark plugs/engine mounts, and vibration or idle problem is still there. It usually get worst with a/c on and when engine is hot.

Here is what i did that fixed my idle/ vibration problem.

I cleaned the MAF sensor which was pretty dirty, this should be clean more often if you have aftermarket intake.
Also, cleaned my throttle body. It was VERY dirty.

Right after i cleaned both of those, car idles higher at like 1200rpm and check engine light came on, so i checked the code. I had a "idle air higher then expected" code.

Then the next thing i did, was the stepping on the brake for 20 times reset trick as well as disconnect the battery.

Since then, my car idles like normal even with a/c on.

Hopes this would help, it's one of the easier things to do that dont' cost much and can be done in like 30mins. worth a try.

would be nice to report back how it work out for you guys.

Last edited by dmak_el; 06-09-2009 at 01:18 AM.
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Old 06-08-2009, 09:54 PM   #2
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what is this stepping on the brake 20 time thing? I just recently picked up my 8 two fridays ago and trying to get as much info as possible....

Im going to clean my MAF sensor and throttle body tomorrow since i bought the car used with 34k on the clock and want to check all the little things over myself so i know how everything sits....
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Old 06-08-2009, 10:00 PM   #3
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Quote:
Originally Posted by Svickstc View Post
what is this stepping on the brake 20 time thing? I just recently picked up my 8 two fridays ago and trying to get as much info as possible....

Im going to clean my MAF sensor and throttle body tomorrow since i bought the car used with 34k on the clock and want to check all the little things over myself so i know how everything sits....
https://www.rx8club.com/showthread.p...ight=pcm+reset

By doing those, it just let the pcm relearn all the values since after cleaning the maf and tb, will affect the air coming into the engine.

Last edited by dmak_el; 06-08-2009 at 10:02 PM.
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Old 06-08-2009, 10:01 PM   #4
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thanks for the link
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Old 06-08-2009, 10:48 PM   #5
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Hmm, i'll have to try this. I cleaned my maf a while ago but not my throttle body.
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Old 06-08-2009, 10:53 PM   #6
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How did you clean the MAF and TB? Did you use a spray?
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Old 06-09-2009, 12:25 AM   #7
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You can use throttle body cleaner to clean the throttle body. They sell OTC at most auto parts stores. I haven't done this with my RX8 yet, but will definitely be on this as soon as I get some free time.

I would recommend NOT using Carb Cleaner or other abrasive cleaners because of their caustic properties which can damage sensors and what not.

They also sell MAF cleaners as well which is what I used when cleaning the MAF on an E46 M3 (these cars especially the SMG-equipped models have loss of power / idle hesitation as well when the MAFs are dirty)
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Old 06-09-2009, 12:34 AM   #8
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Nice. Worth a try.
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Old 06-09-2009, 12:53 AM   #9
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used a q-tip and alcohol to clean the maf, be very very careful. the maf breaks really easy.

and for the TB, just use a TB cleaner spray. reason to clean the tb is because the tb has a pre-set minimum air rate, and that air rate is programed into the pcm. As **** build up on the tb, it will affect the amount of air flow, especially at idle since the throttle plate only open very slightly.
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Old 06-09-2009, 01:00 AM   #10
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im gone have to do this, its really annoying when the car sits there and you can see it vibrate, my rpm's are under 1k

thx for the info will try this and let you know how it went
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Old 08-04-2009, 09:30 PM   #11
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Excellent! this sounds like a good match for my current idle problems. I'll try this one out tonight when I put back my OEM filter.

Cheers man!!
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Old 08-04-2009, 11:18 PM   #12
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Yup that pretty much solved it.

As I see it there was two problems:

1: The coils and wires and plugs seem to be congested (old).
2: The ECU was allowing below average idle rpm rates, where the first problem is MUCH more noticeable.

The problem was fixed because when I reset the chip (turn on car, pump peddle 10-20 times as fast as possible) then I unplugged the battery for 30 seconds, after this - the software reset to a higher rpm level. Very nice! so the second problem is fixed! and the first problem is not as noticeable anymore (still there though) - or at least - the way it was before.

PS: Whenever you unplug the battery. You will need to reactivate your DTS software. How? simple! turn your wheels all the way to the left, and then all the way to the right, then center. Done!

Last edited by Gyro_Bot; 08-04-2009 at 11:21 PM.
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Old 08-05-2009, 08:25 AM   #13
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Where is the MAF and the throttle body? can someone make a DIY for cleaning these parts for those less knowledgeable? I have this problem when hot with AC on.
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Old 08-05-2009, 08:31 AM   #14
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Quote:
Originally Posted by dmak_el View Post
used a q-tip and alcohol to clean the maf, be very very careful. the maf breaks really easy.

and for the TB, just use a TB cleaner spray. reason to clean the tb is because the tb has a pre-set minimum air rate, and that air rate is programed into the pcm. As **** build up on the tb, it will affect the amount of air flow, especially at idle since the throttle plate only open very slightly.
I'd skip the q-tip...you are asking for trouble if you break anything in there. The MAF senor cleaner has enough power on its own, I wouldn't risk it...but then again I don't like replacing expensive parts.
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Old 08-05-2009, 08:41 AM   #15
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^ +1 on the diy
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Old 08-05-2009, 11:53 PM   #16
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Do you need to remove the throttle body completely? Or can you just detach the tube leading to the intake and spray like crazy with TB cleaner?
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car, dirty, idle, idlesvibrates, low, maf, mazda, pcm, power, problems, reset, rx, rx8, rx8club, sensor

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