Idle problem~
 

I just bought my FD for 3 weeks~
It used to be have code 11 and idle hunting from 800 to 1200 rpm and misfiring or choking or "pop" sound from the exhaust problem. Today, I got my car intake temperature sensor replaced, and idle hunting and code 11 are fixed. But now, the idle stays on around 1000rpm with misfiring/choking/pop sound from exhasut....
so what is the problem now??

By the way, the mechanics said my O2 sensor is not working at all. Is this related to the idle problem???

I got very bad gas milage either...


Thx for help~

anyone helps?

Non-functional O2 will definitely worsen gas mileage, as will a heavy right foot!

Idle RPM could have several causes including someone making physical changes trying to compensate for failed sensors. Make sure there are no vacuum leaks, thottle linkage is free, and that dashpot is functioning. If still high you can adjust using air by-pass screw; see attachment.

You got me on the poping sound from exhaust, but makes me suspect spark plugs or maybe a clogged pre-cat; if its still installed.

yo
thx a lots~~~

so the pic u attached was taken from the top of the engine bay or from the bottom??

The picture is taken just below the intake elbow. Here is a shot with the intake elbow removed.

https://www.rx7club.com/forum/attach...&postid=935930

my idle went up to 1200-1500 after i installed a dp... i dunno if it's bad vacuum or if i should just adjust the air bleed screw. i don't want to mess with it yet until i find out about the vacuum first.

thx a lot guys~

I now go to search about the vacuum line~~
thx

oo
also
my car sometimes have low idle..
when i come to stop, sometimes it will go to 500 ~ 600 rpm. It feels like that the engine will stall if not giving gas...

so what;s the problem?

Does your low idle speed recover back up up to normal RPM after you set stopped for a few seconds? If so it's most likely cuased by a failing throttle dashpot.

You can see the dashpot in the picture posted by Jonski. Its the gray colored round thing to the left of the bottom butterfly and about the same diameter. Its threaded end points back toward the throttle linkage where it goes through a mounting flange and its adjustment locked by the large nut

lol jonski said anticlockwise, but the poping is prob spark plugs i think, but does it only pop at idle or is it on trailing throttle???

it pops only at idle when rpm going from 900 to 1000~
When idle is normal, it's stay around 1000 rpm, and hunting around from 800~1000 rpm.
When the idle get low, i can see the voltage drop from 13.5V to somewhere around 12.5 V (blinking) from the greddy turbo timer.
it's stay steady @ 600 rpm, and sometimes it didn't recover unless i give gas

So if dashpot is failed, how much to get it replace???
And is it hard to DIY"?

Thx

The dashpot is easy to do yourself with some simple tools, it is about $100 at the dealer. I just bought a new one, I know it's a ripoff. :)

Check your clutch switch as well, make sure it pops out when the clutch pedal is pushed in. You have to get on your back and look up under the dash to see it, it is at the top of the clutch pedal.. has a white tab the pushes in and out.

Matt

Actually, my dash pot is broken. The piston is stuck inside the cylinder. If you think about it though, my automatic doesn't really need a dash pot, because I don't take my foot off of the accelerator to shift gears.

by the way
how can i know the dashpot is broken??

I have checked the clutch switch~
it's fine~
so what should i deal with?

I have the same problem with my car after it gets warmed up and driven for about 5mins. or so. The idle will drop down to about 5 or 6 hundred and it feels like it's going to stall. I never let it go I always gave it gas because I didn't want to take the chance of having it stall. Also my car seems to idle a little rough when it hits 1,300 at a stand still. Any ideas on this problem. I haven't check my clutch switch yet. I'll try that. $100 dollars for a dashpot? Man that is a rip-off! What will happen if you've driven your car around for a while with a broken dashpot? About my car idleing rough around 1,300 do you think it's the spark plugs or something. I just bought the car a few weeks ago so I don't know when they've been changed last and how long this "dashpot" problem has existed. I will be "serviceing" my engine soon. I'm sure it needs it.

Dashpot is easy to test/repalce. Here's the instructions scanned from the factory manual.

The only problem from continuing to drive with out replacing a bad dashpot is the drop in idle speed when you first let off the throttle. As long as the engine can recover back up to normal idle RPM without stalling you can wait. Myabe setting the idle speed a little higher would help mask this, too.

That is exactly what happens, when coming to a stop I'd push the clutch in and of course put the car in neutral. The idle would drop down real low for a second and then the ECU would catch the idle and bring it back up, a lot of times it would almost die.. and once in a while even die. It is easy to check the dashpot, the plunger gets stuck inside when it is worn out.. lift the throttle linkage off of it and see if you can pull the plunger/tab out any further, just push it in a couple of times and see if it is returning to that position. I had to screw my dashpot all the way up to keep the car running while it was on order.

This may not be your problem though, but at least it is easy to check off the list. There are a lot of things that can wreak havoc on your idle.

Matt

Yeah
I just found out that idle will drop to 500 rpm while clutch and gear is in~~
it sometimes even stall~

so dashpot is the answer right?

need help

low idle problem get more often.
what should i do?