DickH

So the weather is nicer out and I think I am down on power compared to last year. I had noticed that my peak maf values went from 245-250ish to 227-232ish. I have also logged 40-60mph, and 60-80mph times and they seem slightly slower than what used to be normal. Driving around there is no indication that I have a problem, the car seems to run fine without any extra thrown codes. Nothing has physically changed with my car, I had the same results with and without my air filter, I have no detectable exhaust or vac leaks. I have even cleaned and changed my maf sensor without any real difference to logged values.

I am starting to wonder if my problems might be related to the control for the vvti not working right. Is it possible to have some vvti issues without having a check engine light?

2013FSport

iTrader: (2)

Considering the VVTi is a controlled oil leak it very much cares about the oils condition and quality. Do nothing else but change the oil and see if the response comes back.

When I bought mine it ran great but was not to responsive with the throttle. Knowing the dealer dumped some cheap oil in there I dumped it for fresh. Night and day difference.

Maybe consider cleaning the mesh filters at the oil feed pipes too?
When was the MAF cleaned last?

redspencer

iTrader: (1)

Hope you figure out the issue. Perhaps you can try a different OBD reader app to see if the readings are consistent with what you are recording now?

StanleyR

When was the last time you checked your tire pressures?

DickH

I am about 2200 miles since my last oil change. I typically change my oil somewhere between 3000-5000 miles depending on my work schedule, weather and if I feel like doing it in my free time. I checked and my oil still looked ok, oil level was also ok. I have cleaned and tried two different maf sensors to see if it was just a problem with the sensor and it all read about the same.

Where are the mesh filters for the oil feed?

2013FSport

iTrader: (2)

Filters are in the banjo bolts at the feed pipes to each head.

Any chance the trans is playing a role here?

DickH

Thanks, I have ordered 2 for ~$10, I will change them out and inspect the control valves for the vvti on my next day off, maybe an oil change as well.

I don't think I have a transmission problem. I am mostly going off of the fact that my measured airflow is worse compared to last year. The cats are almost a year old, and my car runs lean so I doubt they are clogged. I have eliminated the air filter as a cause and nothing else has physically changed. I am only questioning the vvti system as that controls the airflow.

2013FSport

iTrader: (2)

So what's your current setup? This have primary cats at the headers or no? If no and for some reason you suspect the CATs you might consider making an exhaust leak for a test drive. Something ahead of the CATs.

Does butt dyno notice this or just MAF readings?
I'd think if cats were funked your trims and ignition advance would take a big hit.

DickH

I currently have PPE headers with a custom catted 2.5" dual exhaust, intake is 3.5" with an over sized filter setup. I have peeked under the car and didn't see or hear any indicators of an exhaust leak, I went through my engine bay and corrected the one thing I thought might have been a small vac leak.

My car drives fine with no obvious indicator that there is a problem outside of the recorded values from the OBD port being 6-7% lower from last year. Just recently having decent weather I can't really say that it feels worse than it used to. I am wanting to dyno my car soonish but im still waiting for the tune to be updated and want to sort out any other problems before paying to be disappointed.

2013FSport

iTrader: (2)

You might read my previous post again as the intent was different. Well based upon your response that is.

So, this maybe circling the wagon but if the fuel quality took a big old cr@p between then and now and the timing pulled back, that *could* account for something I'd guess. Anything different there that you know of?

When were the plugs last inspected?

DickH

So I have checked the oil control valves and they all looked ok, also changed the little strainers and did an oil change while I had the free time. I have ordered one of those cheap usb endoscope cameras and intend on using it to check out my valves, combustion chambers and maybe run it down my exhaust to check out my cats. Depending on if I find anything or have the time I might pull the valve covers and see if anything seems off.

2013FSport

iTrader: (2)

You ever find anything and/or get it back to where it was?
@DickH

DickH

No luck yet, but I have been too busy lately to really dig into it. I have tested the intake manifold and it has strong vac at idle. I recently did a compression check and got 175, 170, 170, 180, 175, 175 so that doesn't seem like a problem. I tried pulling the exhaust to to look at the cats and couldn't get a good visual on them. Tried getting a camera in the cylinders but it wasn't all that great, but the valves and pistons looked relatively clean, spark plugs looked ok too for having ~50k on them. I did buy new o2 sensors and they read quite a bit richer compared to my previous ones so I am starting to wonder if I was driving around the entire time running excessively rich. I really don't want it to be the cats but I am thinking that is all that is left. I am thinking about swinging by a hardware store this afternoon and throwing some washers in after my headers to make that leak. The problem with it being cats is that the exhaust hangers in the middle of my car were modified for my custom exhaust so I cant bolt up something else and I can't find an exhaust shop that will swap them out with a straight pipe.

Edit
Threw in some washers to create a ~1/8" gap in my exhaust before the cats and my maf readings didn't really change much.


I am now out of ideas.

2013FSport

iTrader: (2)

What does AFR show, is it mixing like before? You might pull the battery cable and let it relearn.

In your shoes I'd be looking at fuel trim data, make sure nothing is pinned against the rail, verify TP/TPS is opening all the way and as a last resort, get an oil pressure gauge on it. The VVTi is pretty sensitive to pressure loss. It's to bad they didn't fit the car with them stock...

DickH

My fuel trims are usually within 5% with the exception of idle or coasting along on the highway. I had hoped it was as easy as just a throttle body, I have tried two different throttle bodies with the same results. I have also manually moved the throttle body and watched the reading change up to and slightly past what logs show at WOT which all appears good. I have also changed the upper for the intake in case there were any cracks or leaks that might cause problems. I wonder if I could check the oil pressure from the obd port, I might look into that later today. I might throw in some heavier oil in on my upcoming oil change and see if that helps anything.

I have ordered some oddball exhaust hanger bushings which might let me put an alternative exhaust setup on that I have laying around which is pretty much straight through 2.5" exhaust, this will completely eliminate the exhaust side as a potential issue,