New owner, persistent stumbling issue

Hi all, I bought a 2009 MS3 a couple months ago as a running/driving project. It's not working out too good so far. I'm about ready to throw in the towel, but I thought I'd seek help here before cutting my losses.

I've scoured this and other forums, and I did find a lot of very helpful info that's enabled me to fix some things, but I'm at the point where the only thing I can think of next is to start replacing parts....hate to throw time and money at it without some more specific diagnosis, especially if it ends up being something catastrophic.

Quick summary: The car has clearly been poorly maintained, worse than I thought when I first bought it (sigh...). Idle sounds a little irregular, not bad. At high throttle settings (and especially when combined with higher RPMs) there's a lot of hesitation, coughing/sputtering and misfiring, seems to be backfiring through the intake. If I floor it, the sputtering and misfire is really bad, and the car just won't accelerate. Backing off to maybe half throttle or less smooths it out quite a bit (but still not perfect) and the car accelerates decently.

If I give full throttle in neutral (as in the video below), RPM hovers around 5k, sputtering badly, and won't go any higher. Backing off the gas allows RPM to start climbing.

I have a scanner. Fuel rail pressure is in kPa for whatever reason, but I'm seeing around 11,700 kPa, which, according to an online calculator, comes out to about 1700 PSI. My research indicates this is normal, yes?

Gas mileage is pretty bad, mid-teens from what I can tell from limited driving...and that's driving pretty tame (remember, I can't get on it too much).

It's using quite a bit of oil. The exhaust never smokes, but sometimes I can smell a little oil burning. My diagnosis at this point is that the turbo is worn out and contributing to the problem, but I also understand the PCV is a likely culprit to unexplained oil loss. The oil loss itself is not the focus of my troubleshooting right now.

It ran worse before I fixed some things. Specifically, I've done the following repairs and diagnostics:

- Replaced coil packs, also tried moving them around and swapping with another Mazda 3
- New spark plugs (twice....the first set got really dirty very quickly before some of my repairs, need to check the second set now that I've driven a bit)
- Replaced several heat-damaged electrical connectors
- Fixed a boost leak (BPV gasket was AWOL....got a new one installed)
- Swapped MAF sensor with another Mazda 3 I have that runs great. That car continued to run great, the MS3 continued to have the same problem.
- Secured MAF boot (someone had left the clamp loose)
- Checked visually for more vacuum leaks, none found so far
- Visual inspection of wiring, also jiggled various wires and connectors while the engine was running, no change
- Pulled the wiring harness for #1 coil pack at idle, and the engine note did not change. Seems like #1 is just along for the ride, unless the MS3 has some kind of "eco" feature I'm not aware of.
- Before replacing the BPV gasket, I could feel a ton of air pressure escaping around the BPV when I had someone rev the engine, so the turbo is evidently doing what a turbo is supposed to do.
- Compressions are in 170s to low 180s

The car was throwing a bunch of codes when I got it. After my work thus far, I had it down to just one code: P0301 cylinder #1 misfire. But today I noticed another code popped up briefly: P0126 coolant temp insufficient. But coolant temp on my scanner looks normal. The temp gauge always comes up pretty quickly to the middle of the range (I know, it's not very accurate, only giving about 3 approximate ranges, but it does hit middle pretty quick).

I don't know what kind of gas has been run in this car, but I got it down to almost empty and have topped it off with ethanol-free 91 ever since. Also tried some injector cleaner for kicks, didn't help.

Here's a quick video showing my scanner readings while parked. One thing that seems odd: Throttle position D and E only max out at around 66% with the pedal on the floor. I can't find much info about this online to know if it's normal or not.

https://photos.app.goo.gl/2pdipY18Ubc8RqhX9

My next idea was to pull and clean injectors, replace injector seals, and replace the fuel pump internals (would go with the upgraded internals of course). But that's a lot of hassle and money just to be trying stuff.

Matt

 

Welcome to mso!

Sorry about your luck there, car definitely sounds rough. 170-180 for compression is good and yes 1700psi for hpfp is good to.

When testing MAF / coil packs from the another 3 are they the same part number? If they're not the same as the speed could make no change.

Spark plugs should be gapped to 0.027"

Have you checked for connectivity on the coil pack circuit?

Mis-fire can certainly be caused from dirty and leaking Injectors, if you were to try cleaning them I'd pull them and send them to someone that ultrasonic cleans them, replaces filter basket and flow tests them. While you're in there also clean the intake valves if that's the route you go down.

Wondering if the vvt needs to be serviced, you can check for slack in the timing chain with the engine at TDC through the oil fill cap, gives you some idea. Best idea would be with the valve cover off, any scoring on the underside would let you know it's bad too.

As for the oil leak is there any oil in the boost tubing coming off the turbo? And yes stuck PCV valve can also cause issues, you can pop a new valve in I'd recommend upgrading to the damond motorsports PCV plate with one of their OCC cans if you do that (yes more money) but that plate is so much nicer to work with than the brittle stock pos.

 

Either there's an aftermarket intake on this car or maybe a tune, as it's pulling a bit of fuel. Could just be that cylinder 1 isn't firing though, so I'd for sure work on this first since you said pulling the plug did nothing to current symptoms.

Fuel pressure seems fine, AFRs are trying to be fine but failing what with that one cylinder possibly not firing, and manifold pressure seems a bit high (you're hitting 18 psi free revving which suggests either a WOTbox or tune based antilag setup, but it's hard to say with the cylinder 1 thing going on).

By the way, to make things a bit easier, you can just unplug the MAF to rule out the possibility it's a MAF issue; the engine can run in a speed density mode as a fallback (you don't want to do this long term though).

Also at idle just for the shit of it pull the breather hose off the intake and see if smoke is coming out of the port on the valve cover. If you do this with the MAF connected, you'll need to thumb the end that connects to the intake, but with the MAF unplugged you don't have to worry as it won't be metering anyways. Also thumb the port on the valve cover and see if it pulls a vacuum. I would actually consider this to be a pretty important test as it should take only a few seconds and can tell *alot* about the health of the PCV system and engine in general.

I would also try and time the crank if you can just to make sure the crank pulley and crank position sensor are where they should be. Just need the peg for the back of the block as the only specialty tool and they aren't super expensive (~$70) and can be useful if you plan to build it in the future. Alternatively, you can see about borrowing one from a local if anyone is around.

To piggyback off of AW's statements:
1. Compression and fuel pressure are good
2. Just unplug the MAF, it *should* run normally albeit in limp mode. I wouldn't drive it much, if at all like this though.
3. Check the coil pack circuit; IIRC these engines fire in wasted spark mode so there may be some fuckery going on there, as two packs might be linked if that's the case.
4. Check the plugs, post pics of the plugs (not that we don't trust you but a picture is worth a thousand words and can tell us a lot more about whats going on)
5. The catalytic converter can hide smoke and will eventually foul up if it is doing so, so keep that in mind too.

Should be able to figure out what's going on without spending much, if any more money, but might take some time.

 

Post picks of engine bay

Gap the plugs to 0.027

You swapped the mat from a non-speed 3? It won't work if that is what you did

 

Does the car still have catalytic converters on it? Sounds like it could be a clogged cat preventing you from going WOT if your plugs and everything else checks ok

Do a compression test followed by a leak down test. Make sure to do a wet and dry compression test if any specific cylinder tests low

The temp insufficient code could be an error with the thermostat or it could be a skewed sensor reading. Try doing a log if capable of just allowing the engine to idle up to temp and then use Virtual Dyno or make a graph in Excel with your log to see the chart for how your sensor is reading. You could see random dips which would indicate a faulty sensor or connector.

Make sure all your grounds are good and check every single connector under the hood for the engine for corrosion.

 

Awesome ideas, thanks so much. This afternoon I was able to knock out some of the recommended steps.

Plugs are filthy, with #1 a bit lighter (see pic).

PCV line from engine seems to have a bit of vacuum. It's weak, but definitely noticeable. No smoke when I opened up this line.

The big hose coming from the turbo is fairly oily. I assume that confirms my turbo needs replacing?

Disconnecting the MAF connector didn't affect symptoms much, except the engine would only top out at around 3k instead of 5k at WOT and no load. On that note, is it really true that the MAF sensors are different for a Speed vs a standard Mazda 3? The part numbers I'm seeing online are the same for both. My other 3 is a 2010 sedan, I believe it's the 2.0L.

Looks to me like the stock cats/exhaust are in place. I suppose the only way to know if the cat is clogged is to disconnect it?

Forgot to mention I did gap both sets of new plugs before installing, they were spot on.

Attaching plug pics, and the engine bay. As you'll see, the engine bay is a bit of a mess....lots of little brackets and shrouds etc missing. The ECU is just hanging.....I'm trying to find a replacement battery box so I can secure the ECU again. Like I said, this car was obviously not cared for.

You'll notice plug #3 is wet. It appears oil is leaking into the spark plug bay (coil pack is wet too), which I read is usually caused by a leaky valve cover gasket. I forgot to mention this earlier. I've already got a new gasket and will be replacing it (will also check at that time for signs of timing chain marks Awafrican mentioned).

Matt

 

OK so first off, either that car was on fire and had a lot of wiring redone or was heavily, heavily modded. I would not doubt if it just has a ton of electrical issues just by looking at that engine bay pic.

Oil in the turbo could very well be PCV though, so you'll probably want to pull the hose off the throttle body, check for oil there, as well as pull the stock intake (and get rid of it for something aftermarket and WAY easier to work on/with if you're gonna keep it after this) and check for oil on the turbo inlet (just before the compressor blades, this will be your telltale as to if it's PCV oil or turbo oil).

Also, did you pull the hose off the valve cover next to the turbo outlet like I suggested or did you just do the one on the intake manifold? The one on the valve cover should build up a good deal of vacuum over some time (not instantly) but if there's smoke coming out your ringlands are toast. See attached image for the actual hose I'm talking about.

 

Maf part numbers aren't the same. Also people have had bad luck with anything other than an oem maf

Ms3 L3K9132159U

Mzr L32113215

 

unplugging it didn't smooth anything out anyways so that's right out.

 

The MS3 project got set aside for a bit. I actually ended up having to drive it for work a bit because my other Mazda 3 (2010 sedan) had to have a clutch replacement, and is back in the shop AGAIN with an issue related to that job.

I'm going to look at the other things Enki suggested (you're right, I checked at the wrong spot for the PCV test). I'm just having a hard time putting time and effort into this thing when it's got so many other problems.....if the used car market wasn't so nuts right now I'd just buy a better MS3 and move on. This one was clearly abused and neglected.