Engine stumble when coming off throttle

Hjt · Postby **Hjt** » Fri Sep 02, 2011 10:39 am

Hey all,

Basically when I pulled up to a set of lights regardless of the amount of throttle abuse, even driving light the engine wants to stall. This occurs maybe once or twice per journey not every moment I stop.

My idle is set at 900rpm I have a 2002 nb SP. When the car slows to return to idle my revs drop to 300? Or so. The clutch won't save the car from stalling I need to touch the accelerator abit to balance out the revs.

Is this a clutch related issue? Or do I need to adjust the idle higher?

Searches failed to narrow down the fault.

Regards Hayden

Postby **NitroDann** » Fri Sep 02, 2011 12:13 pm

Up the idle, failing that, buy MS3.

Dann

Dweezle · Postby **Dweezle** » Fri Sep 02, 2011 12:25 pm

Sounds like the pesky IDLE DIP.

Do a search on idle dip and see if that matchs your symptoms.

I had a similar thing in my NA, changed to a new Oxygen sensor and it went away.
Other potential fixes include, making sure your base idle is set at 850rpm, well that is for a NA, might alter slightly for a SP?

93_Clubman · Postby **93_Clubman** » Fri Sep 02, 2011 12:56 pm

Techno's 'Idle Dip Solved': http://www.miata.net/garage/KnowYourCar/S7_Idle.html

marty085 · Postby **marty085** » Fri Sep 02, 2011 3:03 pm

Hey Hayden,

My NA8 does the same, it's when the clutch is in, I used to put my clutch in and hold it for a bit coming to a stop (around the suburbs I mean) but now I just clutch in, pop it out of gear, clutch out.. problem solved, rarely get idle dip now.

I tried putting my base idle speed up for a while and it combated it a bit.. didn't dip down so far, but i put it back to normal now.

:mrgreen:

bruce · Postby **bruce** » Fri Sep 02, 2011 3:21 pm

Spark plug leads? But I think you have coil packs?

Hjt · Postby **Hjt** » Fri Sep 02, 2011 4:53 pm

Thanks for all the feedback, ill run some tests and give feedback

marty085 · Postby **marty085** » Fri Sep 02, 2011 5:08 pm

Also, my mechanic friend reckon it's nothing to worry about..

Hjt · Postby **Hjt** » Fri Sep 02, 2011 6:25 pm

Just got my wheels alignment done, it's a bit more aggressive but i'm really happy with the results. I hope i can sort this issue out shortly.

Postby **NitroDann** » Fri Sep 02, 2011 8:14 pm

Checked the clutch switch?

Dann

Hjt · Postby **Hjt** » Fri Sep 02, 2011 9:16 pm

Nope, as i'm unsure what it is, please enlighten me?

BadBong · Postby **BadBong** » Fri Sep 02, 2011 9:50 pm

marty085 wrote:Hey Hayden,

My NA8 does the same, it's when the clutch is in, I used to put my clutch in and hold it for a bit coming to a stop (around the suburbs I mean) but now I just clutch in, pop it out of gear, clutch out.. problem solved, rarely get idle dip now.

I tried putting my base idle speed up for a while and it combated it a bit.. didn't dip down so far, but i put it back to normal now.

I think Marty's got the right idea.

Hayden, just incase you're wondering, my car gets the same thing and despite the fact that Mania has increased its idle, it still does it from time to time.

It usually happens when I'm reversing into a car space... so bloody embarrassing when the whole street things that i've stalled my car whilst parallel park... :oops:

Hjt · Postby **Hjt** » Fri Sep 02, 2011 10:53 pm

Yeah atleast if you have the issue i'm happy we both are up the creek.

P.S The guy at spinning wheels enjoyed telling me your coilover story. He thinks your car appears lower but on the stands is the same as mine oddly enough.

BadBong · Postby **BadBong** » Fri Sep 02, 2011 11:33 pm

And did you tell him the fact that you know the story better than him?

I'll let David know about the ideling problem again tomorow, maybe he'll find a solution for us all :/

Postby **NitroDann** » Fri Sep 02, 2011 11:56 pm

The car has a switch on the clutch, in the same circuit as the neutral switch. They both give the ecu a signal thats your not in gear, and are therefore in idle mode. If theres was an issue it may throw the idle out.

I use my clutch switch for the 2 step and flat shifting :evil:

Dann