High idle/surging

yoshimitsuspeed · Post by **yoshimitsuspeed** » January 3rd, 2006, 12:21 pm

My girlfriends MX3 has been having idle problems. It needs a new 02 sensor so I haven't put much thought into the idle untill I get that fixed but I noticed something that has made me wonder if it's 02 related.
Sometimes it idles right, sometimes it idles high and sometimes it surges. For quite a while I hadn't noticed a pattern untill one day I dropped it into 1st. It went from 700ish to 1500ish. Put it back in neutral and about 10 seconds later it drops back down. It doesn't always drop down to normal but almost always, However it always kicks up very high when you put it in any gear. It seems normal the car might kick the idle up a little when you put it in gear but 1500+ is not cool.
Is this 02 sensor related or is there something else we are dealing with here?

jschrauwen · Post by **jschrauwen** » January 3rd, 2006, 12:44 pm

yoshimitsuspeed · Post by **yoshimitsuspeed** » January 15th, 2006, 4:23 pm

Thanks for looking those up. I did a search but I was looking for idle problems related to it being in gear and nothing came up.
I read over most of those posts and have a couple ideas. Unfortunately it's snowing out and I don't wanna get cold.

None of the post's really related to it being in gear.
Most of the time it idles nice and even around 700 RPM untill you put it in gear, that's when it jumps up and sometimes starts surging. I read that some MX3s are designed to do this but I can't imagine it's supposed to jump up to 1500 RPMS. Could this be something related to that sensor or an in gear idle setting or something like this? I can start looking into the standard idle issues but I would think if it was a vacuum leak or soomething like that it would not be so closely related to being in gear. Nothing else seems to mess with it much either like brakes, or electronics. COuld the ISC be going out and putting it in gear moves it into a sticky spot or something?

jschrauwen · Post by **jschrauwen** » January 15th, 2006, 6:32 pm

Your saying it never happens when it is sitting still but rather only when it's put into gear? This scenario has also been covered in previous posts. You haven't mentioned what items you have checked and verified so far so as to eliminate potential faults. Or is it a case that you are looking for a single answer only to solve your problem. Can't really see that happening since I and the majority of this BB are not mechanics and can't really solve most problems via messaging. If we could we'd put most shops out of business. I've given you enough backround material for you to systematically go through and start eliminating potential faults one by one.
There's no one simple answer here. It's been nearly 2 weeks since you've been given that list and to date you haven't indicated what has been done on your part. How about posting back when you've tried a half dozen or so of potential offending areas. Of course the FAQ's and the online manual are all there to guide you through the more technical areas or your checks. Let us know what you come up with.

yoshimitsuspeed · Post by **yoshimitsuspeed** » January 15th, 2006, 6:38 pm

Well thanks.
I was hoping this might be a common problem with MX3s, maybe something that someone else has dealt with and fixed. Like I said I haven't done much since the weather has been bad and I want to replace the O2 sensor before jumping into diagnostics in case that is part of the problem.

93_mx3_gs · Post by **93_mx3_gs** » January 15th, 2006, 6:49 pm

never heard of bad 02 causing surging. sounds like a vacuum or ISC or possibly TPS problem.

jschrauwen · Post by **jschrauwen** » January 15th, 2006, 8:06 pm

yoshimitsuspeed wrote:Well thanks.
I was hoping this might be a common problem with MX3s, maybe something that someone else has dealt with and fixed. Like I said I haven't done much since the weather has been bad and I want to replace the O2 sensor before jumping into diagnostics in case that is part of the problem.

Of course it's a common problem - look how easy it was to find so many threads relating to that subject. It's understandable not to want to do any outside work during the winter but where I'm from and for most of the general area it's been well above normal temps for the past 2 weeks. Like I said before, you're not going to find that single perfect answer to solve your specific problem right off from the get go. I'm not sure why you would want to focus or change the O2's just because maybe they might be the problem. Sounds like there's more to this that your not mentioning? It's a fairly expensive shot in the dark approach to take. Why do you say in your first post it needs O2's? Have you tried to or are there any CEL codes present?

93_mx3_gs wrote:never heard of bad 02 causing surging. sounds like a vacuum or ISC or possibly TPS problem.

Exactly;
check all vaccum lines,
how dirty is the TB and ribbed intake tubing?,
have you inspected the ribbed intake tubing after a thorough cleaning for cracks or possible leakage?,
have you verified the integrity of the coolant thermosensors?,
is the coolant system properly filled and charged with no air pockets?,
has someone messed or adjusted the TPS?,
has anyone adjusted or messed with any other part of the TB - Idle air screw, disconnected IAC, TB coolant bypass mod etc?,
Start whittling away at these potential areas and you may just solve your problem. BTW, all of these previous points are already included in that list of old posts I proveded. Like I said before, this is not a new problem just one where no one is really quite able to turn around and give you a one line answer and say - "this is your exact problem". We're not that good.
g/l