Please give me some advice for my idling issue

OurP5 · Mar 31, 2003

Hello All,

I have a problem w/ my P5 and need to take it to the dealer. I am almost positive they will give me a B.S. answer when I take it to them. Here is my issue.

When I start my car the Idle jumps up to somewhere between 2500-3000 RPMS. When I first got the car it would idle around 1000. No big deal.

Now the high idle stays for like 5 minutes, even when driving. It is so bad I do not even need to press the gas pedal when releasing the clutch from a stop to forward motion in 1st gear and with no gas pedal I am still cruising at 10 miles an hour.

I know there is supposed to be some type of temperature sensor that will make the car run at a higher idle when it is cold out to make the engine warm up faster. That I could live with but this happens when it is 85-90 degrees out.

Once I run the car the idling issue seems to go away but comes right back the next morning or afternoon, depending on when I go somewhere. I have checked the throttle cable so it is not sticking and made sure the idle adjustment is set correctly. I am at a loss.

Someone told me I may have a bad IAC motor that could be causing my problem. What sucks is I have to leave my car at the dealer's overnight so they can here and see what I am talking about in the morning when they start it.

If you all could provide any insight or if this has happened to anyone else, please let me know.

p.s. I thought this may have been mentioned before but I could not find it in the search. If already discussed. Please forgive me. Thanks, everyone.

azeli73 · Mar 31, 2003

Have you tried reseting the ECU?

1sty · Mar 31, 2003

I doubt it is the IAC. Everyopnes initial idle problems were initialy blaimed on the IAC by other members but there has yet to be a single bad IAC found.

As long as the car isn't modified the dealer souldn't be too bad.

I am sure the first thing others will tell you to do is reset the computer which does cure some weird ass problems now and again.

OurP5 · Mar 31, 2003

Sorry. Having a brain fart

Resetting the ECU.... disconnect negative battery terminal, pump the brakes a few times then re-connect, right?

I haven't tried that yet

1sty · Mar 31, 2003

thats how to do it.

perfworks · Mar 31, 2003

there have been problems with the VTCS solenoid sticking
it is supposed to open the throttle plates after i think 70 degrees
engine temp that might be it
but the dealer would know
they are reqiured by law to fix the problem under warranty
if they dont call mazda
they come down on dealers sometimes for not taken care of these complaints

OurP5 · Mar 31, 2003

Cool. I'll try to reset the ECU. Hopefully that fixes the problem. I don't care much for the service department at my dealership

Bijou-MP5 · Mar 31, 2003

is this same issue as engine rattle problem?

perfworks · Mar 31, 2003

my opinion on why it rattles is a little diferent
when the solenoid is stuck it will force (or try to)keep the plates closed
the rattling is done because the plates actually hit a lip in the manifold to keep it from closing all the way
when you rev the engine it "taps" on that lip because you have air being forced against them but the actuator keeping it closed
i am planning a complete removal of this system soon

Bijou-MP5 · Mar 31, 2003

so... fixing rattling from dealer won't solve idling issues huh?

perfworks · Mar 31, 2003

it should because they first adjust the screw on the actuator to keep it a farther distance away from that lip
then they flash the PCM again to make sure that it is programed to open when reqired
its a bulls*** system but for it to become 50 state legal they had to put it in for cold start emmisions

blynzoo · Mar 31, 2003

The higher idling is to get the cat heated up quicker for emissions (the first cat is for the cold start), and also to heat up the motor faster. The first reduces emissions. And the longer your engine runs cold, the more potential for wear. Whether Mazda actually had the second idea in mind when mapping, I dont know, but I actually was always taught to drive my cars as the ECU now runs it (keep the revs up a bit), for longevity's sake.
This is not as big an issue with synthetics (and the oil squirters, which we do have).

The TSB (search "TSB" and you get the thread) takes care of much of the "rattle," and lowers idle somewhat, not all the way down to 1k.

Perf, did you grind down the lip in the TB as well? I cant remember who else had done that on this site....

perfworks · Mar 31, 2003

the intake is coming out in the next few days to finish the turbo install i may even take apart the VICS or adjust to open when boosted
but the throttle body ill address then too
im not sure i might fabricate something
ill have more info in a couple of days ill let you know

blynzoo · Mar 31, 2003

perfworks said:
the intake is coming out in the next few days to finish the turbo install i may even take apart the VICS or adjust to open when boosted
but the throttle body ill address then too
im not sure i might fabricate something
ill have more info in a couple of days ill let you know

I think I just read another thread where you mention tying VICS control to boost. That is a fascinating idea. I wonder, though, which point you would pick: RPM's, psi, A/F ratio.

Good idea, good to look into. I think it was traveler (if I'm wrong traveler, let me know) who ground down the TB.

perfworks · Mar 31, 2003

upon intial boost
there is going to be some trial and error here because controlling A/F ratio during the opening will be tough without going full rich
but i am determined to get it because it will be a daily driver
i still want it to function for cruising at low speeds
ill let you know how i set it up next week

FuNwaGoN · Mar 31, 2003

ok well here I am the local expert on this issue. I guess I need to finish my write up and post it. I hadn't seen much activity on this lately so I haven't worked on it. Sorry guys. I had like 8 trips to the dealer and one was for a special tech from Mazda NA to work on it. They replaced the IAC valve reset and reprogrammed the ecu and adjusted the base idle. The final fix was a small rubber stopper peice that goes on a switch in the clutch assembly. Not sure of exact placement though. The reson for this is that there is a switch that is connected to the clutch and the computer. When the clutch switch senses pressure it tells the computer to adjust the idle accordingly. The problem is that our cars learn our driving habits and if you drive traffic alot like I do then the computer mistakes slight pressure for the clutch being completely depressed. This rubber stopper makes it so that the clutch pedal must be fully depressed for the computer to recognize it. I have put about 2000 miles on my car since this fix and so far no more idle issues. Keep track of your receipts and go to Mazda NA if you have to but there is a fix for it.

Bijou-MP5 · Apr 1, 2003

sorry but what is NA???
anyway, those will fix rattle and idel problems right?

FuNwaGoN · Apr 1, 2003

Well NA is where you live. You know North America. It can also mean Normally aspirated but in my post I meant the US. Sorry United States. And what are you talking about "those" . I had all of the above cold engine rattle and idle problems. I listed everything that they did to my car and now I have no problems. I had gotten all the way to the point of trying to have Lemon Law put on my car. And if anything similiar happens again then I do get a new car but so far 2000 miles and no problems.

Bijou-MP5 · Apr 1, 2003

NA ...stupid me.
you went 8 different dealers to actually fix your problems?
how long did it take actual mech to fix this problems?
sorry about the constant questions, I just want to aware of things before I make my appointments to dealers.
but..I hate my dealer! I know each dealer is franchise but they always give me crap about things and their parts dept, they don't know anything, and they charge the parts triple from dealer price.

FuNwaGoN · Apr 1, 2003

Welll not 8 dealers but 8 times to the dealer all the same one. Called and got corporate Mazda Involved. If you are having problems the best way to get a resolution is to call Mazda Corporate and get them on your dealer. My dealers attitude changed as soon as they were contacted by Mazda.

Please give me some advice for my idling issue

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