Idle Stalling..
 

Hay guys... Got a question...

I got a 2005 RX8 and i noticed my car start to idle rough. I just did a bunch of work to my car in the way of changing my radiator and radiator bottle.. (started with the bottle but the nipple that goes to the radiator broke on the radiator so I hand to change that too) Any how.. I noticed my car stalling at idle. When I would stop at a light it would go dead. It would start right back up no prob and I did not notice any power loss from the car, but when I checked my Coil packs I found one of them not working. (No Spark Trailing spark plug for Rotor 2) I thought that was the problem. put in a new Coil pack but still the same issue.. I haven't checked my spark plugs yet but would it seem possible if my coil went out that a spark plug could go bad as well due to all the unburnt fuel in the housing? When my car stays on it seems to idle at 750-850 range at times when I rev the engine it will drop to 400-300 range than pick back up to 850ish. Sometimes it just dies though. (was looking at my Access port) HELP!!

Did you clean your MAF & ESS?

Could be something as simple as a vacuum leak or it could be a toasted engine. Start with checking every vacuum line and nipple to insure there are no leaks.

https://www.rx8club.com/attachments/...-locations-jpg

How many miles do you have? Did you disconnect the battery when you replaced your radiator and coils? It could be just the ECU relearning the fuel trims, as well.

Hay thanks guys... Yes I disconnected the battery, when I replaced the coils and radiator, I have 76000 miles on the car. I have cleaned the maf (recently) i have not cleaned the ESS though. I have to double check, I did remove my VFAD but I dont remember if the VFAD SOLENOID Valve is hooked up.. Would that matter? Would I get a CEL if it wasnt?

Yes, what you did with the VFAD matters because if something is uncapped there will be a vacuum leak. You need to get rid of it all (don't worry about the connector just connect it on the dummy spot) and cap the nipple right behind the throttle body.

alright i will check that crap too..

^+1

ok.. i can see that being silly... Ill try to give it another go and see what I get.. When it runs I have no problem with it.. Nothing stands out to be bad with the power.. (that I can tell, I also drive a WRX so im used to my rx8 not feeling the same.) But Im sure going to work on it when I get home..

It's not the fuel trims. Check for a vacuum leak and if it is not that then get a vacuum tester (cheap at harbor freight or the like) and try and get a vacuum reading at idle (if you can) when it's warm.

Ok guys.. update.. I checked the vac lines they are good... made sure all was connected up to the VFAD Solenoid was good it was.... Turns out i just needed to let it learn the fuel trims.. haha... Car runs great with no stalling now... On cold starts it idols high at about 1300 rmp. then settles at about 1000. When it warms up it idols at about 800-900 after driving it dips down for a sec. to about 500-600 ranges then back up to idol strong at around 8-900. So far so good. I drove it the 16 miles to work this morning and no issues at all... Thanks for all the help guys.... P.S. just got to check how it is on hot starts now.. that will be my lunch time test..

How many times did you start it and let it idle after messing with the intake. After you did it a time or two after the coil change, etc. it should have been good, it shouldn't have taken more than one cycle to reset the trims. Odd. But that's good man, glad you got it worked out.

Yea man that's what I have thought before.. When I started the car after the work I did with the battery re connected I took it around my block and it would stall and die at the lights.. I took it home and checked the coils and found the last one on the fritz. I replaced it and it still would not hold an idle.. Here is the kicker.... (i think) I changed maps with my access port back to the stock set up. (Still Idled funny) I think i did not give the car a chance to learn the maps.. So yesterday when I got home I drove it and it was all good.. I let it warm up for like 10 mins. Holding good idle and it was ok.. I think I changed maps too quickly not letting the car learn anything..the strange part is when I changed maps before I don't remember any (learning time) my car needed??

Ah, that explains it.

Hi Guys, I'm having similar trouble after unplugging the battery, she drives fine, just wont hold idle when I slow down. It dies at lights or stopping. Oddly, if I just start it up, it will idle okay after a bit. Once I drive, dies at idle. Thoughts?

Also, my engine light is on. not blinking but on...

Also, what is the map in which you referred? Tx

Same deal, keep your rpm up at idle. And let it relearn the fuel trim.
Clean your MAF, air filter and reset your ESS.
The code is probably P0506.

If you are getting p0506, it'll take much longer for the ECU to relearn fuel trim.
The engine is simply not getting enough air by factory setting. Dirty MAF/air filter can cause it.

Once your idle is smooth, the code should go away soon, if it's p0506...

Dewd?
Ahhhhh dewd?

How can you possibly come up with all that from the little that is posted?

That guy didn't even know what a map was?

it could a completely unrelated issue?

I'm not saying you're wrong but it is very presumptuous

BTW ... this whole learn the fuel trims thing is BS if you ask me. I've reset dozens of RX8 ecu's which wipes the fuel trims and not one of them stumbled on idle.
There is something else wrong if this happens

Allow the car to learn the fuel trims on it's three or four cycle. A cycle is when you start the while the engine is cold (or allowed it to cool down after a drive), allow it warm up to at least normal operating temp and then turn it off. That is what many will refer to as "cold-start". During these first few cycles, you will not hear the air pump work; however, you will hear it turn on once the ECU have learned the trims. Nevertheless, as 9krpmrx8 have suggested, check and make sure you do not have any vacuum leaks.

Respectfully
The most important part of this post is check for vacuum leaks.

The ECU does not need 3 or 4 drive cycles to learn trims.
I may know little but of this I do speak with experience.

LTFT can be learned inside 5 minutes.

As a matter of fact ... I saw it just the other day

edit -- read this in a "two guys having a beer at a bar tone" ... will accept counter argument ... I'm not trying to piss anyone off

The fuel trim was from experience also, at least with my car before I had my reman-engine. But surely, on a healthy engine (good compression, new coils-plugs-wires, and no leaks) it can be learned within 5 minutes as you stated, to which I did with mine on my fresh-reman' that has 1,300 miles two weeks ago. But, still, we cannot rule out the possibility of the vacuum leak.

Absolutely .. agree on vacuum leak.

IMO this is likely more the cause of issues then it's recognized.

On my own vehicle, I do see LTFT develop over several drive cycles like mentioned.
And I will agree that best practice when tuning is to let that develop and work itself out.

But ... but ... if you reset the ecu and the car struggles at idle for more that a minute and you drive it down the street and it won't idle at the stop sign ... this is not a trim issue ... something else is wrong. IMO

I think we are saying the same thing ... I think

IMO idle trim does need drive cycles. Idle issues are caused by other issues.

BTW I'm enjoying the conversation ... next round of beers on me. Tarbender! Beers plz

Oh and we've hijacked the thread (which was kind of useless anyway)

Pressing on the issue, WreakLoose did replace the reservior and radiator; in order to do that, one must remove the VFAD(assuming that he has the high powered engine). It may be possible that one or two of the tube(s) connecting the VFAD actuator, solenoir valve, and vacuum chamber weren't properly connected. Just as 9krpmrx8 had illustrated.

When I had the reman-engine installed. I picked up and drove the car, did a walk through the engine bay and sure enough, the hose connecting the solenoid to the VFAD actuator was not installed causing a dip in my RPM.

Thanks guys...looked through it..didnt see a vac leak. Drove it for a while..a good hour or two
...still wouldnt hold an idle when i stopped. This was daytwo...yhe odd thing is all that changed was unplugging the battery...

On dqy two..when n it was cold it would idle okay...but not after indrove it. Took it to the dealer..dont remember the code number...said.the number meant one of four things...ac on off or others. Will see more on monday. I gave up at that point..

Thanks for all your ideas..

Oh..and i did the 80 break pedal pump too...well see

What year and mileage do you have? Has any of the spark plugs, wires, coils, or battery had been changed? Find out what code(s) you have, have AutoZone or O'Reilly's do it for you.