Running too rich with bad idle
 

The car has been running very rough lately. The Idle is terrible and it runs very rich. The AP will only read as low as 11.2 AFR and the car pretty much runs under that all day long. I have a few data logs at home that I can post up later.

so far I have gone through countless weekends trying to fix this problem.

Changed Ignition
Changed spark plugs and wires
Changed Crankshaft sensor
Changed Fuel Pump
Vacuum tested the SSV and VDI
Vacuum tested the car itself
Changed the MAF
Made sure the APV cycles
Seafoamed

Now I am looking to order new Solenoid Valves for the SSV and VDI because I am getting a P0661 code.

I am really lost as to why the car is running this bad... Perhaps I missed a large vacuum leak :dunno:

Any ideas guys?

How do the injectors look in the logs? Normal latency, etc? If there was a problem there it seems like you would get multiple codes but the sensors the PCM uses are only so sensitive and sometimes they don't detect every little issue.

A vacuum leak would be my guess. Have you had a compression test done?

no compression test yet. I have vacuum tested at full temp off the UIM. Holds a strong vacuum. This is how I usually tell if a car has low compression.

Damn ur car runs really rich

Did u try to uninstall ap for a while, go back to stock and see what happens?

New front O2 sensor.

I'm betting the O2 sensor is kah-putski

What are the vaccum readings at operating temp at idle (if it idles long enough).


I am betting this as well. At least this is something you should replace anyway.

havent tried uninstalling the AP yet.

i actually replaced this too, but I replaced it with a used one so it still could be the issue. plus with the car running very rich I may have ruined it anyway

the vacuum reading is around 14.

As the idle has gotten worse over the past week or so this number may be different so I will have to get a new reading.

That's pretty low man.

You can't count on vacuum readings if you have other, obvious, problems with the engine. Once those other problems are corrected, the vacuum reading will be more reliable.

From the factory service manual;

• SSV solenoid valve malfunction
• Connector or terminal malfunction
• Open circuit in wiring harness between main relay terminal C and SSV solenoid valve terminal A
• Short to GND in wiring harness between main relay terminal C and SSV solenoid valve terminal A
• Open circuit in wiring harness between SSV solenoid valve terminal B and PCM terminal 1L
• Short to GND in wiring harness between SSV solenoid valve terminal B and PCM terminal 1L
• PCM malfunction

SSV solenoid is the one I want to replace. While testing them I broke one which I now have in there to block the port for the Air Pump (which I have deleted). The vacuum is holding fine there.

Ray, did you get my emails? I sent over some data logs and the links to the pics I had. Also, Kalen never sent out that tool :sad: So I will go ahead and ship it right away.

Datalogs do no good but you can resend the e-mail if you like.

i'm in the same boat as you, i just found out i'm running very rich and my idle is horrible. i already replaced the SSV and checked my injectors.

Same boat, I really think it's my catalytic converter but I'm unsure on how to verify that before I risk it at Mazda. (Not in the position to waste $90 on a diagnostics test unless its under warranty smh...)

What are the fuel trims? If they are maxed out at 25 then you have no more available

Could be the MAF...if it reports higher flow than actual the car will dump fuel to compensate for the air it thinks it is getting...and then the closed loop will try and trim it out...till it hits max trim..and then it can't do any more

What do you have for a map in the AP? Have you altered the MAF scale in the low flow ranges?

What injectors? Turbo?

Usually a vac leak will result in the opposite....car gets more air than the MAF reports....so less fuel is injected...the closed loop tries to aadd fuel till it hits max trim and then that's all it can do as well....

:icon_tup:

If you have done anything to upset the way the maf sits or with the screens etc then it can build some big trims .

updates?

Well its weird, but the code indicates that their is a vacuum leak, and it says that the readings could be misled due to something cat-related... I'm not completely sure. I thinking of just pulling the exhaust apart to see what might be rattling in the pipe

Update
 

please if you fixed the issue can you tell me what you did because I have the same exact issue and I have tried everything and nothing has worked

Hi Tyler
Sorry about your problem but I don't think you'll get a reply this post is 10 years old.
The original poster Chris had a boosted RX8 so there was alot more going on there, I'm not sure about the other guy Jpaul26.

So to be clear your car is running rich at idle?
Do you have a modified intake?
Mileage and year?

I run super rich at idle and my car jerks when I put it into drive
I have a cold air intake
I have a 2004 with 74000 miles

Thanks.

Ok so not all aftermarket intakes are equal.
Typically you'll find (my experience as well) that only the AEM/Mazdaspeed or Revi Racing Beat intakes are worth installing on the RX8.
As a point of interest the RX8 in fact came with a cold air intake.
So what you can do is check the Maf Screens inside the intake and make sure they are not bent or turned on a angle.
I've taken apart several AEM Intakes and each one have the Maf screens all turned out of position.
This will totally ruin the air flow across the maf and create all sorts of havoc.
While you have all that a part inspect and clean the Maf with Maf Cleaner spray (you can buy this stuff at most automotive stores).
You should be able to check this in your driveway.

Couple more questions:
- Do you know what brand of intake you have?
- Do you have a check engine light on? If so you should get that checked.
- Do you still have a catalytic convertor installed? These are known to fail and cause all sorts of issues especially on the earlier models.
- It sounds like you're able to read the AFR's to determine it is running rich, can you also read the Long Term Fuel Trim (LTFT) and Short Term Fuel Trim (STFT). These can often provide a good indicator of what is going on.
- And lastly, only because someone will say it - When is the last time you changed the coils and plugs and have you done a compression test? (its the RX8Club mantra to ask this it seems)