SBarnes

Starting a new thread because the only thread I seen that had this same problem did not have a resolution.

i have a 05 Rx8 6 speed with 66,xxx miles
It starts fine but will not idle, will not rev unless I feather the gas. If I unplug the maf it will run a lot better but still won't idle and sputters some.
Things ive done so far:
New spark plugs
New ignition coils and wires,
New Maf
Checked for vacuum leaks and did not spot any
Cleaned the throttle body and intake

I will post a video with the maf plugged in so y'all can see exactly what it's doing.

SBarnes

Here is a link I uploaded it to YouTube, said the video was too long to upload on here.

NotAPreppie

What happened before this started?

Are there any other codes behind that check engine light in addition to the one for the disconnected MAF?

Have you cleaned your ESS and reset the ESS profile?

How did you search for vacuum leaks? Did you use a smoke machine? I know some people recommend spraying carb cleaner at various air connectors but there are so many that it would be easy to miss some. Did you make sure that the vacuum caps didn't rot off of the service nipples on the lower intake manifold?

If you don't have one, get a bluetooth OBD-II adapter and app for your phone. Tell us what the short term fuel trim and long term fuel trim look like. Also, tell us how much air flow the MAF is reporting.

SBarnes

Thanks for the reply,
i bought it and it was already running like this, additional engine codes are misfire in cylinder 1, and system is too lean, i didn't clean the ess because it looks brand new but I will do that tomorrow. I have reset everything I know - pumping the brakes 20 times within 8 seconds, had the dsc light because the battery was bad when I purchased the car so I reset that. I sprayed carb cleaner at every location I seen that could possibly leak and it didn't show signs of a leak, I removed the upper intake to inspect the seals and they all look good, pulled all the vacuum hoses off to make sure they were not clogged, I just ordered a Bluetooth obd 2. I will post those results when it comes in. The service nipple caps looked good but I replaced them anyway just to be sure, I did add a new ground wire from the frame to the engine and it runs a lot better but still idles a little rough. I am still getting the system is too lean code and cylinder 1 misfire, I replaced the spark plugs, ignition coils and wires as soon as I got the car so I don't know why I'm still getting a misfire. It has a midpipe so that may be why I'm getting the code system is too lean? It looks like it was very well taken care of, starts right up every time cold or warm.

NotAPreppie

If you're getting misfire and lean codes you likely either have too much air or not enough fuel. A midpipe will not affect this. If you're running cat-less you should get a P0420 (catalyst below efficiency) code.

Step 1: stop running it until you get these sorted out. If your engine isn't already trashed, misfires will trash it.

Step 2: verify the lean code by looking at your fuel trims and MAF rate when your OBD2 adapter arrives. At warm idle, your MAF should be reporting between 4.5 and 5.5 g/s. Less than this indicates a vacuum leak. Fuel trims between -8% and +8% are no big deal. IIRC, you have to be up over +20% to throw a lean code.

Step 3: go over your intake and vacuum systems with a fine-tooth comb. If possible, get your hands on a machine to smoke test your intake. It makes finding leaks stupid easy. Read here for more info.

Step 4: Check your fuel pressure. A weak fuel pump may not be providing enough fuel which will cause the engine to run lean. You'll need a T-connector and a gauge and you may be able to rent this as a kit from an auto parts store. The fuel line connections are between the brake booster and the UIM.

Step 5: best of luck and godspeed.

SBarnes

i borrowed a friends code reader and recorded the short term long term and the maf.

Andrew5190

iTrader: (1)

Has to be a sizable vacuum leak. With LTFTs that high, it should very obvious, even using the carb cleaner method.

NotAPreppie

What Andrew5190 said.

MAF rate is low and LTFT is pretty high. You've most likely got a leak somewhere.

SBarnes

Okay I will check all vacuum lines again tomorrow, I will try to get a smoke machine to test with. How would I test with a smoke machine and is there anything else that could be causing this problem?

SBarnes

Another thing I've noticed is the cel will go off shortly and it will come back on and every time it is the same codes, sometimes the cylinder misfire 1 code will not be there.

NotAPreppie

Here's a good resource on how to smoke your intake.

Misfire events don't always trigger a persistent code even if they cause a flashing CEL.

Andrew5190

iTrader: (1)

It can be more than vacuum lines, too. For instance, my vacuum leak that threw LTFTs that high was caused by one of the SSV bolts being loose (I broke the first one and was too loose on the replacement ). Also verify all of your gaskets on the upper intake manifold are in good shape, no pinches or breaks.

SBarnes

Alright thanks for the info. I will be home in an hour and I'll take the upper and lower intake off along with all the vacuum lines to make sure they are in good condition and going to the right places. I'll post an update as soon as I get done to let y'all know what the results are.

Andrew5190

iTrader: (1)

Lower should be fine...and it's a complete and total bitch to remove with the engine in the car. Focus on the upper.

SBarnes

is that gap suppose to be there ?

NotAPreppie

IIRC, that's normal. Any air that gets through there will be metered by the MAF sensor.

SBarnes

Okay good, is the oil refill cap suppose to have a gasket ?

NotAPreppie

Yes, I believe mine does.

SBarnes

Don't know if that would be the cause of this, mine doesn't but everything looks good, I've got the upper intake off as we speak, all the gaskets look good, one of the bigger hoses that connects to before the throttle body on the intake goes to the omp, one goes to the oil refill and the other one goes where?

NotAPreppie

SBarnes

How does that look ?

Andrew5190

iTrader: (1)

Those values all look spot on!

What was the issue?

SBarnes

Ltft-1.8 ~ 3.7
Maf 4.75 ~ 5.45

After I reinstalled the upper intake and throttle body I installed the aftermarket intake that was on the car when I bought it and it still didn't fix anything so I took the air filter off to clean it and I noticed whoever installed it before I got it pushed it as far up on the tube as it would go so it wasn't getting much air at all through it so I went and bought another filter and installed it properly. Bam runs like charm

NotAPreppie

I was going to guess it was the VFAD nipple behind the throttlebody.

SBarnes

I thought it may have been that too but it had a cap on it