Seems like this problem is getting more common. My battery died one day and after getting it jump started, I started seeing the infamous idle issue immediately. As the engine revs down, it would just stall completely. I already tried resetting the ecu with the braking techninque and disconnected the battery for half an hour. But the idle is still persisting.

So I took the car to Alhambra mazda here in Los Angeles and they told me I needed a new ECU, throttle body and some kind of harness. That's gonna set me back $2k.

Do I have to bend over for them? Or does anyone know of a rotary specialist in L.A. that can actually fix my problem without resorting to replacing unnecessary parts? From various searches, I know that the ssv can get gummed up and can be cleaned. But that is definitely our of my expertise.

 

What year and mileage?
Have you replaced coils, plugs and wires lately?

Start with cleaning your MAF.

Then check the "Similar Threads" at the bottom of this page. There are plenty more threads that cover this as well. Just do a search for them.

 

Could be ground issue.

 

04 with 32,000 miles. The coils were replaced about 4 years ago. I'll try to clean the maf tonight and see the result. What type of solution do I need to clean it with?

Also, I connected an ODB scanner and it returned the P0506 code, which is low rpm.

 

You can use electronics contact cleaner, carb cleaner or brake cleaner.

You coils sound pretty old. It might be time for coils and plugs. Both are easy to do yourself. This will make it a lot cheaper. About 140 for all 4 coils and 80 for plugs if you go through vendors on the site here. I'd do wires too, but it might not be necessary. They run 60 to 80 for a set. BHR's ignition system is a good option and very popular.

Try your MAF first though. As VashGS said, check your grounds. Check that both terminals on the battery are tight. if they are, check the chassis ground and any others you see.

How to for MAF cleaning

 

It's not bad coils. Your computer reset its idle. It happens when you install a new computer. Turn of your ac. Crank the car. Give it enough gas to rev it to what it normally idled at. Sit there for two or three minutes. Let it drop, if it drops low, rev it to the roof then back to revving at idle. I had this problem when my batt died. Eventually your 8 will start idle jumping from normal to low then smooth out. Just make sure you let the idle smooth out every time you crank it. It shouldn't take more than five or six days of normal. Driving. Hope this helps:

 

Good call Bonestock. I didn't think about it relearning the fuel maps and the like after his battery replacement.

 

Yes, you need 2 full drive cycles to relearn the fuel maps after disconnecting the battery.

 

Thanks for the input guys. That's what I love about the Rx8 community. Just got some maf sensor cleaner. So i'll clean it. Reset the PCM again. Try what bonestock suggested. And drive it for several cycles.

BTW, how long of a drive is one cycle? And what should I be looking for regarding grounding issues?

 

Drive Cycle is driving the car after the thermostat opens. Followed by a period in which the car can cool completely off then another drive cycle through thermostat open.

 

Correct, it must cool off below a certain temp(I think it's ~122 degrees or within ~11 degrees of ambient?) before that 2nd cycle is acknowledged. So you can't just tool around the block a few times, shut it off, restart right away, and go for another spin. That doesn't count.

 

Thanks. I figured since my 04 did the same thing, that might be what it is. I didnt know about the two cycles. I was just going by what a Mazda mech told me. Thanks guys. I'm not used to the 8 yet. And all the fd fixes involved new apex seals

 

So I cleaned the maf and went through 3 cycles. But idle still drops to stall point once the car warms up.

Also, check engine light returns code p0506, u1900 and c0073.

Anyone know of a rx8 specialist in L.A.?

 

P0506 has typically been caused by a vacuum leak, a bad throttle body, or a stuck SSV valve.

 

u1900 is a communication error which usually means the obd reader you are using is somehow incompatible. c0073 is a traction control code. looking it up it is usually related to wheel speed sensor errors. check that none of the plugs for the wheel speed sensors have come loose.

 

Well... I guess the next step is to clean the TB and see if that works. I'll keep you guys updated. Hopefully I won't have to move to the SSV. I saw the video on it and seeing how many parts were removed to get to it scares me.

 

panda does ur rx8 came wit an intake. if u got an aftermarket intake i.e. K&N, Racing Beat, etc.. good idea to clean that as well. u can pik up the cleaner kit at ur local Oriely or autozone. BTW which MAF cleaner did u get there r 2 different kinds. There is the oily 1 or the desolve on contact. U shouldve got the desolve on contact type. The bottle should b silver or dark gray. I had simillar problems b4.

O yea there is JRX Rotary located in Irwindale if u still need them. Its about 10 miles east from alhambra mazda.

 

mine did that also. the mazda mech said that that should go off. it's because the computer was reset and it needed a speed reference. i drove it arond the block, presto. gone. he also said if that didn't work. drive approx a mile. stop and turn your wheels all the way right, all the way left, back right and then center.

 

I used the crc maf cleaner in a gray spray can. I also have K&N air filter on it.

Today I took apart the intake and got access to the throttle body. The edge is pretty encrusted with black soot. is this consider really dirty? And how do I go about determining if the TB is bad?

I also appreciate the feedback that this community is providing me. Doing this stuff is giving me more confidence about working on my car. I'll give it another week or so of trying to resolve this problem. If all else fails, I guess I'll have to limp this car to JRX and get some pros working on it.

Here's some pics:

 

I was just about to clean the TB and I read the cleaner instruction and it said not to use it on rotary engines. I got a can of CRC throttle body cleaner from autozone. Is there any rotary specific TB cleaners?

 

SUCCESS!!!!

After cleaning the throttle body, the car is back to normal and idling is extremely stable. My guess is that the TB was pretty jammed up and the fuel trim was mapped to that. The resetted fuel trim wasn't able to handle dirty TB.

Thanks for all the suggestions guys.

 

Good deal......hope it lasts!
Could you tell.....was it gummed up with oily residue? If so, might want to think about a catch can.
I can't remember if you said what it and the intake looked like in an earlier post or not.

 

Agree....if the MAF is all gummed up with oil you should be checking your oil level, considering getting the TSB to reroute the oil overflow, considering an oil catch can if you don't get the TSB and investing in a funnel.

 

The TB and UIM had some black oil residue. But it wasn't really gummed up that bad. The TB shutter didn't take a lot of effort to manually open. The MAF sensor, though, was pretty clean. But I better think about doing the catch can since the SSV probably has just as much oil residue as the TB.

I'm also thinking about pulling out my K&N filter for the paper ones. Will that help reduce oil residue build up in my intake?

 

The oil residue in your intake that we are talking about is somewhat expected, it is designed to vent pressure from the system. A small amount of residue can be expected in your intakeand isn't necessarily bad. However, excessive oil residue is caused by overfilling your oil or filling without a funnel. Changing from a K&N to an OEM air filter will not do anything to help you out.