Piston Pete

Sometimes, my car will idle irradically. Especially during initial warm-up, like in the morning, but also intermittantly at stand stills while driving around. It's pretty pulls pretty smooth through the power band, but something like the plugs or cables seem to be going or perhaps something more serious. To help better draw a picture of my problem: the car is parked and idling, the idle is not smooth and steady, it sputters/stuttes, then smoothes out, then stutters again. Kind of like, mmmmmmmmmmmmmmbupbupbupbupmmmmmmmmmmmmmmmmbupbupbu pbupmmmmmmmmmmmbupbupmmmmmmbupbupbupbupmmmmmmmmmmm mmmmmmm...
what could this be?

Thanks,
Ant

Roland

Sounds normal to me. Your stock ECU works in loops and it will bubble and studder and do all kinds of **** bone stock especially if its cold or hot. In hot weather it has absolutely no torque on the low end and sometimes will stall from stoplights. When it is cold it will run like jack **** it is best to let it warm up instaed of fighting with it. Also let it warm up idleing or at least don't rev it above 4k when cold. Sometimes the temp needle will be in the middle but its still too cold to run good cuz the gauge has only three stops. As far as your idle thats pretty normal as long as it does not hunt (blown motor). It is also possible that you have a vacuum leak. If you're still concerned check your compression. If it is fine, over time you will learn to love your car's personality.

Piston Pete

I hear ya. don't get me wrong, there isn't much that I don't like about 'er, but I'm sure we can agree that we just want the best for our cars. That's the thing though, it doesn't feel normal. Perhaps you mean normal in the sense that it's normal for this car to feel like this with the mileage and years it has?

Anyone else have a sputtery idle even when warm and running for a while?

Mahjik

iTrader: (1)

Do you have a boost gauge installed? What's your vacuum?

luneytune

Search for idle, you will find the adjustment procedure. It will correct your problem. IMHO

Piston Pete

Don't have a boost gauge yet, but I can see how a vacuum leak would cause a stuttery idle. I will be getting one of those soon. Another note: the stutter almost seems to be being caused by something like a clogged/faulty injector or a failing plug. Can it be something else?

djantlive

Are you idling high? If it idles over 1100rpm, you probably have a vac leak, could be your LIM gasket, among many other possibilities.

When it stutters, what rpm range?

Piston Pete

Not idling high. Idle speed appears normal at 800-750rpm. The problem is noticeable while looking at the engine. It shakes or sputters sporadically. It can also be felt while sitting inside. I'm simply assuming that a perfectly healthy engine will idle smoothly in a steady hum. Mine sounds like hummmmmmmmmmmbupbupbupmmmmmmmmmmmmm..
get it? Maybe it's just cables or plugs. I'll be replacing these soon.

jeff8932612

Roland, You mentioned that sometimes rx-7's will die from the heat. My car died twice in the last week or so. It happened both times at traffic lights and they were both hotter than usual days. Can you explain a little more about what is going on? Is this normal? Is there anyway i can prevent it?? thanks alot. -Jeff

redrotaryrock8

i have been fighting a bad idle myself. and there are so many things that can cause a bad idle that its not even funny. an intake leak past the TB. too much tension in the accelerator cable. faulty fast idle cam. incorrect tps sensor. faulty idle control solenoid. problems with egr valve. problems with waterthermosensor. problems with intake thermosensor. problems with fuel thermosensor (just to name a few).

try living with it as long as you dont get a check error or your idle goes up astronomically.

if you want it really fixed, i would suggest checking the idle control solenoid, checking the fast idle cam mechanism, checking the tension in the accelerator cable, checking the dashpot mechanism. and if you dont live in california, just go ahead and disable the egr valve.

-bilal

Piston Pete

what does the egr valve do?

2-Rotor

First off what mods do you have? Second shuttering can be because of a clogged catalytic converter. When was the last time you had a tune-up as well? And finally check all of your intercooler couplings for cracks, rips, or if they are just plain loose.

redrotaryrock8

egr stands for exhaust gas recirculation. what it does is that it takes in exhaust gases and puts them into the engine. the purpose is to inhibit the production of pollutant gases (or to minimize the production). emissions thing strictly. disabling it doesnt impact performance. if at all, it only helps in smoother idling (if the egr valve is clogged up or dirty).

saiyan

iTrader: (1)

Did you fix your idle yet? ...I'm trying to get more ideas how to fix mine too..

Piston Pete

Nope. The thing is I'm broke, but when I get the loot I'll be doing:

-new battery w/better ground
-plugs/cables
-vacuum hose job
-fuel filter
-cleaning injectors or getting new ones
and I'll also be checking/cleaning various sensors things like TPS's and stuff.

Ant

suganuma

broke??

get a credit card!.....an FD's best friend.....

toddah

Both my 82 12A NA and my 93 TT FD do this idle thing, I think as long as it is just a small bump in the idle and you see no drastic reduction in idle speed your OK. My 82 has done this cold since new (now 50K) been tuned many times by myself and Mazdz shop, Still did it. My FD makes almost identical "bumps" and runs very strong.
I think it a normal rotary thing. as long as it runs good warm drive it an have fun...

redrotorR1

like redrotaryrock8 said, there's a ton of things that cause a weird idle. and like said before, search using idle as your keyword. there's been tons of post about fixing idle problems.

from experience, i'd say the most common causes are the tps sensor, the map sensor, or some idiot messing with the dashpot (idle screw).

boh

This kinda sounded like the problem that I have. I am not sure, but my car would have a hard start in the morning and smelled really bad. When my engine was cold...the rpm would run high around 2,000 or so. After a few weeks, my car got worse.

Then I started to overheat. I brought it to the shop and I was loosing coolant pressure. All hoses were changed including waterpump. But I was still loosing pressure. It was determined that my coolant seal went bad...and guess what, I am rebuilding. I hope that this is not your problem, but I had other symptoms too. Coolant smell coming from the exhaust.

Good luck!

Piston Pete

It's strange. If I run my AC, and sitting at a light (idling), it'll stall all of a sudden. I cut the AC off and never stalls. Another note (mentioned this already in another thread) once the engine is warm and idling, if I blip the gas a little, on the way down, the revs will dip to almost the first mark on my tach, which I think is 500rpm. Now, if I have my lights on and blip again, the revs only dip to 600-650 rpm. It appears somewhat normal, but not all the way down to 500rpm. It sometimes feels like it's goind to pass 500 and stall.

saiyan

iTrader: (1)

I think I have a leak somewhere in the vacuum hose, cause I only have about 12hg vacuum on idle... I already replace most of my hose, but couldn't do the rest, cause I mashed out those screws on the backside of the firewall, so this weekend I will try to bust those screw out and dig through my hose again.....

Piston Pete

Ok, go for it