Stumbling, hesitation, numb gas peddle, Fuel trims crazy, Lean, P2187.

So unfortunately the Mazda is driving like shit these days and I'm getting desperate for some help.

- Verified no vacuum leaks or boost leaks, I used the smoke method, soapy water method, and carb cleaner method. Whenever I pressurize the system, all I get is flow coming out of the valve cover.
- verified spark plug gap at .026" and changed spark plugs within the last 1000 miles
- cleaned MAF sensor
- stretched ignition coil springs
- added fuel system cleaner

nothing is working.
I'm starting to think the primary o2 sensor or MAF sensor is going bad

I took a 37 min log on the way to work this morning. I thought almost a dozen times I was going to have to pull over. Its just strange that sometimes my fuel trims are fine and then the next moment its at 26%

Any help is appreciated

 

bunch of questions to help narrow it down:
Did it happen all of a sudden, slowly get worse, or after a particular mod?
How are you tuned, what fuel, has any of that changed?

Just an example; I recently got my car back after a lengthy engine build. Had evidence of a vac leak but could not find it for shit. Turns out it was the methanol solenoid fittings. They were still loose, and because they were on the opposite side of the throttle body it wasn`t getting enough pressure from the test to be visible. I ended up pressurizing it with the key on and a brick on the gas pedal and found the leak. Not to say you`d have the same issue (your sig says no meth yet), but it could be a similarly activated problem.

 

Thanks for the response.
slowly got worse over the past month or so. I got my first stumbles about a month ago but it came and went, never felt like I needed to pull over. I figured since my WOT logs and idle logs looked good it was a non issue but then it just got worse and worse.

I'm on a mild tune from Dizzy. 93 octane, original K04, no changes this year.

the issue seems to worsen as the car warms up. Wondering if there is a pre-o2 exhaust leak?

 

I though the same two things when I was fighting with mine. I was actually headed to the parts store to beg them to let me swap in a new maf sensor just to see if it fixed the problem (I`d have purchased it if so) when it dawned on me to try what I did. O2 sensor failures *tend* to not be flaky on/off problems. I`ve read a few people had luck cleaning the maf sensor, might try that and see if anything changes, even if it comes back shortly it`ll be an indication.
[doublepost=1507135294][/doublepost]something you might try is logging maf voltage and comparing that to instances of the problem or simply looking for anomalies.

 

What does your fuel pressure look like at idle? Could be your Fuel Pressure Relief Valve. I see in your logs you are at around 60 sometimes which is not anywhere near where idle should be. You should only be around 60 with key on when the car is cold because that is the pressure the pump gives. Mine went out at 135k and caused fuel cuts and I could not WOT.

 

Good call. I can`t open the log from here so great observation Sr Tightlips.

 

If you do need one THIS is the cheapest I could find it unless you have the mazdaspeed discount stuff. The signs of a bad relief valve would cause all sorts of odd fueling issues.

https://www.tascaparts.com/oem-parts/mazda-fuel-pressure-valve-l3k9132j0

 

Thank you so much for this! i am going to clean my spill valve tonight as a first measure and then buy this part if that fails
[doublepost=1507145869][/doublepost]

 

To clean your spill valve use Naptha which can be found at home depot or anywhere for 5$. Then use Redline fuel system cleaner to lube it. Do the same thing with the HPFP. You should really only have issues with spill and hpfp if you are running heavy e85 like more than e30 mix. Never use rotella or something that will react with ethanol to lube or you will get black sticky death.

2-Pack VM&P NAPTHA QT by KLEAN-STRIP
by Klean-Strip
Link: http://a.co/jdG2Nji

Red Line 60103 SI-1 Fuel System Cleaner
by Red Line Oil
Link: http://a.co/6iOzjE1

 

Thanks again, you lube the components with Redline S1-1? or just add it to the gas tank and go for a drive? or both?

 

I lubed them after cleaning and added the rest to the tank.

 

just got done cleaning and lubing the spill valve, I broke the O-ring and had to wait until my girl got home to borrow her car to get another o-ring. Autozone nor Advance had a 27mm O ring so i ordered some of Mcmaster for a long term install. fuel pressures are looking a lot better. I had a hell of a drive to pep boys after work to get the red line fuel cleaner and concluded that the fuel pressures dropping to 60 psi 100% correlate to the stumbling and hesitations. I got two bottles of the red line fuel cleaner and drove to home depot. Even that made a huge difference I had a much more pleasant drive to home depot to get a 32mm wrench. Here is the most recent map, its not perfect but I have a lot more confidence in the car. Ill continue to monitor on my drive to work in the morning to determine if relief valve is next. I do here a clicking sound in the engine bay when i listen to it idle which I read in another thread could indicate relief valve.

see attached log after spill valve clean and lube.

 

Awesome to hear it is getting better. When my relief valve was bad it would make the hpfp sounds like a turbo whistle at idle and light revs. I think it was due to over working the hpfp as it tried to keep up with something that would never build pressure. A quick way to check is to pull the relief valve and see if you can blow through it. It should only crack at 1800psi or so. If you can blow through it then it is bad or you are super human. be careful when you remove it as it does have a washer with it, don't loose that as it seals it.
[doublepost=1507169902][/doublepost]I looked at your log it is looking a lot better. Lowest HPFP was 266 , that is still fairly low for idle but much better than 60.

 

JohnnyT coming through in the clutch

 

Once again my drive to work was much better than yesterdays. Thanks so much for the help. Everything is looking pretty a lot better but I still feel like my fuel trims are too high and inconsistent, I thought the goal was to keep these between -10 and 10, centered around 0.
Mean = 2.16, Stdev = 8.04.

FYI I didn't do a full fuel pump cleaning, just the spill valve. I'll do the relief valve check tonight. Thanks

 

Easiest way to see if the relief valve is bad is watch fuel pressure and shut the car off. It should hold ~400psi (normal idle pressure) for a few seconds and slowly drop over a period of a few minutes. If it drops to 60psi immediately after shutting the car off your relief valve is definitely bad.

 

Yeah , the youtube video I posted also has an nice guide to check it via data.

 

Just saw this thread... I'm pretty sure the SV I ID'd as the fuel pressure issue was the end of that. Usually relief valves cause other problems and the car looks fine at WOT...AFR's are bang on. At this point I kinda just want to get my hands on the car and find out what is going on to cause the trimming problems. My primary suspicions are:

1) Downpipe to turbo connection leak or other leaks in the vicinity of the primary O2 past the turbine wheel
2) Purge valve solenoid stuck open, possibly in conjunction with an EVAP system leak somewhere
3) MAF sensor or wiring, or air straightener issue. Something like that.
4) EGR stuck open

The reason I suspect #1 is because the exhaust stream is going noticeably lean in closed loop at times. OP has leak tested the intake systems multiple times to no avail and on top of that this is not acting like a gross vacuum leak. It also is not acting like a faulty injector because misfiring is not happening and misfire codes aren't stored.

As far as order, I would test #2 first by plugging the IM side of the purge valve and letting the purge valve VTA. Then swap MAF sensors. Re-test. Then the shitty exhaust stuff is left after neither of those do anything... But really it's not that bad to just pull the DP off the turbo and he has the Cobb so access isn't horrible.

 

Thanks John @VTMongoose

-EGR is blocked off and deleted so I doubt that's contributing but ill look into it.
- I have a turboXS downpipe, not Cobb, regardless, it shouldn't be too bad of a job.

I had purge valve issues when I got the car about 18 months ago and its been replaced at least a few times with cheap Chinese replacements over the life of the vehicle so its very well possible. I can do this test this weekend.
-I'l need to borrow your spare MAF sensor.

Thanks again, everyone

 

Its definitely not the purge valve, did the test above and after turning the key off, pressure slowly rose to~1850.

-it looks like the threads in the Cobb intake that hold the MAF screws have come loose and are coming up out of the intake body. The O-ring is fine and doesn't look like it has breached the top but could definitely be playing a role under heavy vibrations. I don't have a spare intake yet so it will have to wait until the weekend.