high rpm at idle

[Nooby31]

Hey everyone,

I got my MAF and TB cleaned about a week ago and ever since then I have noticed considerably higher rpm when the car first starts up in the morning and even after it has warmed up.

The car now starts up with about 2100-2300 rpm in the mornings and takes a long time to come down to about 900-1000. It then stays there until I drive the car. I have also noticed that when I press the brake the car starts to slow down but the rpm jumps like 200-400 as the brake is applied and the car is slowing down. I got my front rotors and pads changed so could that be a reason for the jumpy rpm?

Are these normal findings or something I should get checked out?

thanks

[McGuyver_3]

2100-2300 is not normal. 900-1000 is normal especially in colder weather and when driving off it is normal for the rpms to drop a bit.
As for this "jump" in RPM, could be a downshift.
By cleaning your TB and depending on how dirty it was it could have something to do with the high idle. My suggestion would be to hook up a scanner and see if there are any pending faults in the computer. Also check the MAF wiring to make sure it was plugged in properly, no wires are tugged. Also make sure the MAF was reinstalled properly. If the TB was removed to be cleaned make sure connections are proper and the TB is seated properly and the gasket is in place. If all this checks out, I would disconnect the battery and let it sit for about 1 hour. Reconnect and try starting it again.

edit: changing your brakes would not affect the RPMS. At least I have never experienced this before

[sarujo]

The OP did not reset the ECU after the TB/MAF cleaning. This is a direct symptom of not resetting the ECU. Nooby31 should disconnect the negative battery connection, press on the brakes 3 or 4 times to bleed any remaining charge, and then leave it disconnected for 10 mins.

I had the exact problem after my recent cleaning and the ECU was not reset properly.

[stock3]

The OP did not reset the ECU after the TB/MAF cleaning. This is a direct symptom of not resetting the ECU. Nooby31 should disconnect the negative battery connection, press on the brakes 3 or 4 times to bleed any remaining charge, and then leave it disconnected for 10 mins.

I had the exact problem after my recent cleaning and the ECU was not reset properly.

+1 on resetting the ECU, although your procedure seems a bit involved. In my experience disconnecting the negative battery for a minute or two is sufficient to reset the ECU and fix high start up RPM and idle.

[TheMAN]

the semi-official mazda way has been to disconnect the battery and hold the brakes for 30 seconds... I add on top of that by touching the negative battery cable to the positive post to help the discharge process... it works because sometimes I see a spark
no need to wait 10 minutes, other cars like old nissans need time, but not mazdas :)

[sarujo]

Nope that wasn't enough for me. Had to do it again later and using the process I outlined worked perfectly, and I know things reset b/c the driver's side door window door lock button required the quick re-calibration.


+1 on resetting the ECU, although your procedure seems a bit involved. In my experience disconnecting the negative battery for a minute or two is sufficient to reset the ECU and fix high start up RPM and idle.

[Flagrum_3]

the semi-official mazda way has been to disconnect the battery and hold the brakes for 30 seconds... I add on top of that by touching the negative battery cable to the positive post to help the discharge process... it works because sometimes I see a spark
no need to wait 10 minutes, other cars like old nissans need time, but not mazdas :)

Disconnect the negative battery terminal and press the brakes for 10 seconds...10 second's being more then enough to discharge any capacitors in the system. But I suggest strongly that no one touch the negative cable to the positive battery post, for any reason...This is extremely dangerous and unnecessary.

_3

[TheMAN]

not dangerous and it won't hurt anything... I've done it plenty of times, and this was suggested to us from the mazda training centre

[Flagrum_3]

not dangerous and it won't hurt anything... I've done it plenty of times, and this was suggested to us from the mazda training centre


If so, that is just unbelievable!...Anytime you are dealing with a battery and do something, anything, that can produce sparks is always been a big no-no, period...Safety should always come first...I guess Mazda didn't teach you that.

_3

[McGuyver_3]

Not to step on any toes here but at work we do "hard resets" which consists of removing the negative and hooking it to the positive. Never seen a spark but it is not uncommon.

[Flagrum_3]

Not to step on any toes here but at work we do "hard resets" which consists of removing the negative and hooking it to the positive. Never seen a spark but it is not uncommon.

Not saying it can't be done, just not safe.


_3

[TheMAN]

how is it unsafe? the battery only gasses during charging and especially at elevated temperatures or a high current rate (it gets hot on its own due to chemical reaction of charge process)
the fact that the battery terminals will spark anyway when you reconnect the battery means you're over reacting, because if that was so dangerous, every single battery being connected by millions out there would have exploded.... fact is it hasn't, and any battery explosions are a low percentage regardless of whether you touched the negative terminal on the positive post or not.... battery explosions happen due to battery damage or something stupid you did such as charging the battery too long on high current or connecting jumper cables improperly causing so much spark on top of a gaseous battery, it explodes

if a tiny little spark is so unsafe, stop fixing your own car, stop driving your own car, or do anything else for that matter.... go build yourself a bubble and live in it

[Kiyomi]

Not saying it can't be done, just not safe.


_3

agreed. not a safe practice. i dont care if you tell me it doesnt do that 99/100. its that 1 time, when something can happen.
why take any kind of risk, no matter how miniscule when you can just undo the negative terminal and press the brake for 10 seconds. didnt realize people cant wait 10 seconds for safety.

[TheMAN]

fixing your driving your car is not safe too, so it's not a safe practise.. don't do it! build yourself a bubble!

[Kiyomi]

fixing your driving your car is not safe too, so it's not a safe practise.. don't do it! build yourself a bubble!

what does that even mean? do you mean by me fixing my car to have better brakes, suspension, and quicker throttle response that its not a safe practice? my o my
or did u mean that driving in itself is not safe? please explain.
its thinking like this (just do it, 99% nothing will happen) where it gets someone hurt not only at ones home, but in the workplace, especially when your working with electricity.

[TheMAN]

the act of getting under your car to fix it is unsafe, no matter the amount of safety precautions you take
if you're afraid of a little spark, you might as well put down those wrenches

it's not a huge lightning bolt spark
the spark you MAY see from touching the negative terminal on the positive post is much smaller than the spark you would see when you reconnect the battery properly (positive to positive, negative to negative)... based on the OMGZSPARKUNSAFE logic, you might as well not even change your own battery or disconnect/reconnect the battery

there is NO continuity involved when you're touching the negative terminal on the positive battery post, no electronics get damaged

if a tiny spark is so unsafe, you might as well not get gas yourself, use a gas stove, or use a propane barbecue grill for that matter


everything we do in our daily lives have risk, even the simple act of going to the bathroom has risk
if you're so worried about these small risks, build or find yourself a bubble and stay there because there isn't anything that you do that has zero danger

[Kiyomi]

the act of getting under your car to fix it is unsafe, no matter the amount of safety precautions you take
if you're afraid of a little spark, you might as well put down those wrenches

it's not a huge lightning bolt spark
the spark you MAY see from touching the negative terminal on the positive post is much smaller than the spark you would see when you reconnect the battery properly (positive to positive, negative to negative)... based on the OMGZSPARKUNSAFE logic, you might as well not even change your own battery or disconnect/reconnect the battery

there is NO continuity involved when you're touching the negative terminal on the positive battery post, no electronics get damaged

if a tiny spark is so unsafe, you might as well not get gas yourself, use a gas stove, or use a propane barbecue grill for that matter


everything we do in our daily lives have risk, even the simple act of going to the bathroom has risk
if you're so worried about these small risks, build or find yourself a bubble and stay there because there isn't anything that you do that has zero danger

you just said that your fine with taking extra risks no matter how miniscule. that in itself is not a safe practice. why not take the route where there is no risk or there is lesser chance of harmful risk? thats all. that is what i have a problem with, especially when suggesting it to another member. by your example, getting under the car. if you got to, then do it. you take the necessary precautions and put down ramps or jacks or whatever. take the same precaution with electricity and do everything in your power to not take any risk, or the least possible risk. and that is not what you are suggesting. if it was anything else about the car, id be siding with you.

[TheMAN]

are you dense? like I already said, when you change a battery or reconnect the battery, you'll still get a spark from the negative post as that is the final connection you're supposed to make on the battery... how is that less risky than having a disconnected negative cable and touching it on the positive battery post? OMGZSPARKUNSAFE! the spark is so small when you do that, it is as small as a static electricity discharge when you reach for a door knob on a dry winter day... it's not a huge spark 1cm away from the battery post, and you're not making freaking lightning for as long as you have the negative cable near the positive post... OMGZSPARKUNSAFE! the size and duration of the POSSIBLE spark is a fraction of a second and is smaller and shorter in duration than reconnecting a battery

stop being a pansy
you two have no idea how ridiculous you sound when you never even done this before

[Kiyomi]

are you dense? like I already said, when you change a battery or reconnect the battery, you'll still get a spark from the negative post as that is the final connection you're supposed to make on the battery... how is that less risky than having a disconnected negative cable and touching it on the positive battery post? OMGZSPARKUNSAFE!

stop being a pansy

i could care less about a spark, cause im an apprentice electrician and see this on a daily basis. the guys who say stop being a pansy at work are usually the ones who end up getting hurt. why take an extra step when u can just go and press the brakes without touching the battery anymore than it has to be? .05 amps is enough to stop your heart or change its rythm. i wouldnt be taking it lightly like you are and making sarcastic jokes. im not saying that the battery spark does produce this. people will take from this thread what they need.

[TheMAN]

because you're ALSO pressing on the brakes after you done that!

this is freaking 12 VDC, not 120, 208, 240 VAC!

the risk level of touching the negative cable on the positive post is AS MUCH if not less than the act of reconnecting your battery, so tell me why is this even risky? there is ZERO CONDUCTIVITY OR CIRCUIT CONTINUITY when you have the negative cable disconnected from the battery, touching the negative cable to the *connected* positive post of the battery isn't going to do a damned thing to hurt you because of that... the amount of "hurt" you're going to get is as much as putting each hand on top of the two battery posts... the human body has much too high impedance to even allow such continuity to happen from a 12 VDC battery

DC electricity is nothing like AC electricity... you don't have to remind me to be extra careful around 120 VAC because I ensure all circuits are off, not touch anything if I don't have to, and I always make sure connections are extra secure

you're over reacting and sounding like a pansy, simple as that

[Kiyomi]

because you're ALSO pressing on the brakes after you done that!

this is freaking 12 VDC, not 120, 208, 240 VAC!

the risk level of touching the negative cable on the positive post is AS MUCH if not less than the act of reconnecting your battery, so tell me why is this even risky?
you're over reacting and sounding like a pansy, simple as that

im trying to promote safety. like i said, even if the risk is miniscule, why take more risk.
personally i find 347v the scariest. keeps you held.

[TheMAN]

you just don't get it, do you? there's not any more risk doing this than reconnecting the battery

[Kiyomi]

you just don't get it, do you? there's not any more risk doing this than reconnecting the battery

i do get it... no need to be snobish.
yes that is a risk. but why take it further and put the two terminals together? this i find just stupid and bad practice. thats my opinion.

[TheMAN]

it's not stupid practise, it is approved industry practise
again, this is DC electricity, completely different from AC!

for the last time: there is zero conductivity and zero continuity once you disconnected the negative cable from the battery... touching the negative cable on the positive battery post (with positive cable still connected) isn't going to conduct electricity... all it will do is allow discharge of residual electricity from electronics... no damage occurs..... this is completely different from AC electricity where even with nothing else connected, the hot or neutral wires can conduct electricity through you as you're a ground path, and kill you

DC IS NOT AC
the safe practises of AC does not really apply to DC!

[Kiyomi]

dont be fooled. DC can in many cases be worse than AC. dont give me that.
besides, i have my opinion and you wont change that as do others. again, people will take from this thread what they need. nuff said.

[TheMAN]

this isn't HVDC, it's LVDC, and as I said... 12 VDC cannot pass through a human body... impedance too high
what you are saying as a building electrician can't really apply to automotive electrics, sorry but your concerns are unwarranted

the fact is, the act of touching the negative cable on the positive post is taught at tech schools everywhere, including auto maker training centres
if this is stupid practise, then all mechanics, auto engineers, and auto mechanic instructors are stupid

[Jackal]

Good stuff guys! Interesting debate of pansy bubble vs dangerous spark!

[fywdyl]

you just don't get it, do you? there's not any more risk doing this than reconnecting the battery
TheMAN
Yes there is, touching the negative to the positive can sometimes cause acid juice to explode from the battery and hit you in the face.

[TheMAN]

and it's just the same "sometimes" as reconnecting the battery cable onto the corresponding posts, your point is?

[fywdyl]

and it's just the same "sometimes" as reconnecting the battery cable onto the corresponding posts, your point is?
TheMAN

I don't get it...
My point is that explosive acid spray is a danger.

[TheMAN]

yes it is, and that danger is just the same as when you disconnect/reconnect the battery WITHOUT even doing this "touch negative cable to positive post" thing.... you still have a spark... why do you think battery manufacturers and charger manufactures have warning labels saying wear eye protection and gloves?

batteries off gas hydrogen as part of the charging process, but in a well ventilated area, it is never concentrated enough to just simply explode... much like when you go light up your gas stove or propane barbecue grill, you turn the knob to "high" before hitting the lighter or throwing the match in.... those few seconds of gas leaking isn't enough to just explode when you do finally ignite the stove/grill

batteries explode because of damage, clogged vents/pressure build up due to bad charging methods... they won't just explode in your face so simply through the act of disconnecting a battery, much less touching the negative cable on the positive post

you guys are making a big deal out of this... give it a rest already!

[fywdyl]

yes it is, and that danger is just the same as when you disconnect/reconnect the battery WITHOUT even doing this "touch negative cable to positive post" thing.... you still have a spark... why do you think battery manufacturers and charger manufactures have warning labels saying wear eye protection and gloves?

batteries off gas hydrogen as part of the charging process, but in a well ventilated area, it is never concentrated enough to just simply explode... much like when you go light up your gas stove or propane barbecue grill, you turn the knob to "high" before hitting the lighter or throwing the match in.... those few seconds of gas leaking isn't enough to just explode when you do finally ignite the stove/grill

batteries explode because of damage, clogged vents/pressure build up due to bad charging methods... they won't just explode in your face so simply through the act of disconnecting a battery, much less touching the negative cable on the positive post

you guys are making a big deal out of this... give it a rest already!
TheMAN
Explosive acid spray is not to be taken lightly. It's very dangerous stuff!!!!

[TheMAN]

yeah, every single battery ever installed by people exploded in their faces
OMGZSPARKUNSAFE! everyone head for the hills!

[fywdyl]

yeah, every single battery ever installed by people exploded in their faces
OMGZSPARKUNSAFE! everyone head for the hills!

I'm glad we are seeing eye to eye.

[Nooby31]

sorry for the long delay in posting a reply.

I will disconnect the negative battery cable and press on the brake for about 2-5 mins tomorrow!

thanks everyone!