funky idle, anyone know?

[david103]

My mx3 and i guess many other's have an idle that jumps up and down from 800 - 1600 rpms when you hit the brakes. does anyone know what causes this? O2 sensor? its not the idle control thingy, cuz i adjusted that and nothing happened. its the most annoying thing in traffic....<BR>thanks for help.

[renef]

There are three areas you need to check. I have this happening in my ride today and I'm getting annoyed.<P>1. check all of your vacuum lines and EGR valve<BR>2. Not enough fuel may not be getting to the injectors, or perhaps through the injectors (dirty injectors, dirty fuel filter, weak fuel pump)<BR>3. Worn Idle Speed Control valve. This thing is usually the guilty party. It's located under the throttle body. <P>All of the above are a real pain in the a-- to troubleshoot. I'm not looking forward to it.<P>RF

[Cybin]

Sounds like my problem except mines dies. I'll be coming off the highway and the car just dies. The idle used to flutter big time but now the engine flames out. 70mph without powersteering and power brakes sucks. Does your idle flutter when you hit the brakes? I've got to fix this on wendsday. So I'll keep you posted.<P>-Cybin [img]shrug.gif"%20border="0[/img]

[renef]

HELL YES! I usually have it happen if I come to a toll and I slow from 70 to zero. The car shuts off! <P>I already changed the fuel filter. That wasn't it.<BR>I increased the fuel pressure via my custom FPR just a little bit. That wasn't it.<BR>I checked the EGR. Nope. not it either.<BR>I checked for fuel leaks. nope<BR>I cleaned the air filter. nope<BR>I took off the air filter. nope<BR>I turned the idle screw up a bit. nope.<P>I really hate my car sometimes...<P>RF

[david103]

ok, called a local auto shop and told them the whole story of my idle problem. they asked if i had an aftermarket intake. i said yes and they said that was the cause. <P>hold on, i know what youre thinking, BS! they said the engine was recieving TOO much air and didn't have any idea what to do so it gets screwy like that. But that doesn't explain why it only does that when the brake is pressed, or stops when the A/C is on...<P>sooner or later i'm going to put a fuel pressure reg/riser on there, maybe that'll work. <P>anyone and everyone please help with any advice or ideas.

[MX-3 Extreme]

Hey guy's, it can be three things ,and one is guaranteed to solve the problem:<P>First and most important: TIMING,this will do it forsure.<BR>Second : plug gap or bad plugs<BR>Third : Exhaust <P>Trust me the timing thing is very important and will make the idle jump up and down when touching the brakes and will go away when you are at a complete stop.Ajust your timing and this should go away. If not then try the others, if it comtinues the e-mail me and I will help find the problem. I have changed soo much in my show mx-3 and have ran into these problems and my car only has 29000km on.<P>Killer Mx3

[gardenstateparkway]

i just got a completely stock 92 4 cyl sohc last week. there is nothing aftermarket on it and the previous owner had all work done at the dealer. i did full plugs and wires, new air filter, cap and rotor, pcv valve, and cleaned the throttle body and idle air control valve this past weekend and the problem appears to still be there. i also reset the throttle to take any slack out of the cable. i replaced only the down-pipe on the exhaust, but will be doing the rest of it this week. there's no way its an aftermarket parts problem. the idle still fluctuates when i turn the lights on and off and when i hit the breaks. also, the car still wants to stall when i come to a stop. i coming to think i need to replace the IAC valve. hadn't thought about timing.

[zx6r]

Heya,<P>I'm having this exact problem on my '96 RS, I JUST BOUHGT IT TOO!!! AARGH!!<P>Has anyone found a solve for it yet?? If i take it to mazda and say "check it" i'll be probably 3-400 bucks out..<P>any suggestions will be appreciated<P><BR>thanks!!<P>-Tawheed

[david103]

as soon as i save up some money, i'm going to get my comp. codes read. a local shop has a far more technical manual than the dealerships and they said they could do it. i just don't want to pay to find out what the problem is...<P>dave

[Guest]

BAC valve is my guess. Also a little idle fulctuation on the I4 engine is normal, thats how they r designed. u r wasting time if the problem is not severe.<BR>just my 0.02

[Guest]

oh and i say bac valve cause 3 mazda dealers told me. the valve keeps opening and closing at idle causing a variation in amounts of air taken in and hence the idle going up and down.<BR>And it is SOOOOOO expensive to fix, $700cdn from mazda just for the part plus $200 labour

[heatherc]

okay..i had this same problem on my 92 RS about 2 months ago....took it to the dealer and they cleaned my BAC valve and reset my idle...it still vibrates....the mechanic said it is a sign of the cars old age..ya can pull the manifold and replace the valve, but there are no guarantees..cost me $70 to do this..it idles rough once in a while..but i can deal with what it does now..to replace the valve would involve probably at least $300..<P>heather

[pakix2000]

This one is easy. Whats happening to your car happend to my car. It is because you adjusted your idle incorrectly and your ics is going bad. Re-adjust the idel to where it used to be. Put the car in diagnostic mode and turn the idle screw until the rad. fans come on. Leave it there.<P>P.S. when you hit the breaks and your idle jumps around does it seem like your revving at some 1?<P> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by daverman:<BR><STRONG>My mx3 and i guess many other's have an idle that jumps up and down from 800 - 1600 rpms when you hit the brakes. does anyone know what causes this? O2 sensor? its not the idle control thingy, cuz i adjusted that and nothing happened. its the most annoying thing in traffic....<BR>thanks for help.</STRONG><HR></BLOCKQUOTE>

[gardenstateparkway]

how do you put your car in diagnostic mode? what does it do?

[renef]

In the diagnostic connector, short the GND and the TEN pins. The codes will read out as flashes on the Check Engine light.<P>The Mazda 323/Protege book from Haynes is the correct one to use for SOHC 1.6 B6E engines.<P>You can also reset the Check Engine by removing the Negative battery cable and pressing down on the brake pedal for 10 Seconds.<P>I'm reading this back and something is not right. I'm going to check the book and re-post the instructions.<P>I'll get right back to you...<P>RF