CX-5 2.0L - P0304 P0171 - Help needed please

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Mazda RX-7
Need some help troubleshooting a 2013 Mazda CX-5 2.0L w/130k miles

Original problem: DTC P0304 – Cylinder 4 Misfire and sometimes a P0300

Symptoms:Misfires / hesitation under load only. Idles and rev's freely in park fine. Higher RPM driving seems OK too. Lower RPM with high load, bad.

Things tried:
1. Replaced all 4 spark plugs (BOSCH 9683 OE Fine Wire Double Iridium)
2. Swapped coil #4 with coil #3
3. Inspected intake pipe after MAF for leaks.
4. Cleaned MAF with MAF cleaner spray. Didn’t look bad and Torque app reports reasonable MAF readings.
5. Inspected PCV hose for leaks
6. Tried spraying carb cleaner around intake manifold seals and various other potential leak areas. No change in RPM.
7. Took to Mazda dealer for diagnosis. Mazda recommends replacing all 4 coils based on a TSB and current DTC P0304.
8. Purchased 4 new coils from RockAuto and installed myself (easy to do, 5-minute job, no reason to pay anyone).
9. Tried disconnecting each coil at idle. Engine sounds equally rough with any one cylinder disconnected. On all 4 coils it sounds quite smooth/normal. Engine is smooth in park all the way up to 4000 RPM (where I stopped). Seems to start bucking (misfiring) under load only.
10. Filled 3/4 of tank with 93 octane and some Techron fuel cleaner.

No dice. Still getting P0304

I found TSB that Mazda Tech was referencing about the coils:
https://static.nhtsa.gov/odi/tsbs/2016/SB-10085446-6903.pdf

I’m a little annoyed that it described the exact troubleshooting procedure I did by swapping coils, yet tech said TSB said to replace all 4 coils.
At this point I lost all faith in going to dealer to diagnose issue. We’ve paid $127.78 in diagnostics and replaced 4 coils needlessly.

I started a deeper dive in my own troubleshooting. Didn’t want to do this earlier in the week because I just got LASIK and I couldn’t see well.
I connected the CX-5 to my HP Tuners Scanner and pulled what PIDs I could with it.
First thing I noticed was the LTFT (Long Term Fuel Trims) we basically getting maxed out ADDING FUEL, while the rear O2 sensor (B1S2) was at a near constant .800v or higher (RICH!!!)
My first scan didn’t have data for the front O2. I learned later that it’s not a narrowband in this car but a 5-wire wideband O2 sensor for B1S1. I eventually found the PID to give me lambda, but not before I replaced the front O2 sensor with a new DENSO 2345059 {#PE01188G1A}.

So with a new front O2 sensor, I went for another drive. I noticed under load (greater than 75kPa MAP) is when the engine misfires. As I mentioned before, in park you can rev the motor freely to 4000 RPM without it getting rough.

My scan shows the WB O2 ratio to be withing 1% of the Commanded EQ, yet the rear O2 is pretty consistent staying above .750v (rich) unless I do a deep decel and then it will read .100v. Never really is any middle ground with the rear O2

I think I verified that the High Pressure Fuel pump is working to spec. 435 psi at idle and ~2100 when engine load is above 60% and above 3000 RPMs. Using this procedure here and this one here.

Still getting the #4 misfire, I decide to replace the #4 injector. While I have the intake manifold off, I notice quite of bit of carbon/oil build up on the intake valves. I cleaned those up with carb cleaner 2 valves at a time (valves closed). They cleaned up reasonably well.

No more P0304 but now getting a P0171 (Lean Bank 1) and still has same symptoms.

Still observing:
-Normal WB (front) O2 operation. I never see lean accept on deep deceleration.
-Rich rear O2's
-Short Term and Long Term Fuel Trims adding a lot of fuel, especially at higher loads when car hesitates / misfires.

I've since tried:
-Swap the MAF with a known good one
-Unplugged battery for the entire night
-Cleaned MAP sensor
-Performed a compression test: 160, 160, 170, 160 PSI respectively.
-Performed a leak down test: All cylinders gave no significant loss.


So what is your opinion? I don't understand the logic of this car. Why a lean code, when the commanded EQ is close? Why is the rear O2 reading rich?

I have a HP Tuners scan if anyone has it and wants to take a look.

Appreciate any help. I'm stuck. Trying to help out a family member with their CX-5.

-Andy
 
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Mazda RX-7
I might have missed it, but have you replaced rear O2 sensor yet?

I have not, but would that effect drive-ability? Is the computer throwing more fuel at the cat because it's rich?

Here's a snap shot of where it typically misses / hesitates:

Engine RPM (SAE) 3,385 rpm
Throttle Position (SAE) 32.2 %
Timing Advance (SAE) 24.0
Mass Airflow (SAE) 37.0 g/s
Intake Manifold Absolute Pressure (SAE) 80 kPa
Engine Coolant Temp (SAE) 144 F
Intake Air Temp (SAE) 52 F
Fuel Rail Pressure (SAE) 2,026.2 psi
Absolute Load (SAE) 55.3 %
Equivalence Ratio Commanded (SAE) 0.989 λ
WB EQ Ratio 1 (SAE) (2) 0.988 λ
O2 Voltage B1S2 (SAE) 0.743 V
EVAP System Vapor Pressure (SAE) -340 kPa

Short Term Fuel Trim Bank 1 (SAE) 0.8 %
Long Term Fuel Trim Bank 1 (SAE) 20.3 %

Vehicle Speed (SAE) 29 mph
 

yugrus

Contributor
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CX-5 GT
Rear O2 sensor readings are fairly stable in any case. But you noticed a sudden drop under certain conditions... If you have infra-red thermometer, see what are the temperatures before and after the cat. The chance of it being clogged is miniscule, but still... You've done everything else.
 

GJ-Molestor

Banned
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2011 BMW 528i, 2015 Mazda 6, 1995 Nissan Maxima Manual
Buy a new ignition coil and replace the one in misfiring cylinder. Very easy to do yourself and much cheaper. I recommend changing all 4 spark plugs. Worn plugs wear out your coils faster.

Swapping coils isn’t going to fix the issue because you’re just putting the faulty coil into a different cylinder.
 
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Mazda RX-7
Buy a new ignition coil and replace the one in misfiring cylinder. Very easy to do yourself and much cheaper. I recommend changing all 4 spark plugs. Worn plugs wear out your coils faster.

Swapping coils isn’t going to fix the issue because you’re just putting the faulty coil into a different cylinder.

You didn't read the whole thing sir. I moved #4 to #3 to see if the misfire moved with it. It did not.

All 4 coils are replaced.
New plugs
New front o2
New #4 injector
 

yugrus

Contributor
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CX-5 GT
It never occurred to me to take a look at fuel trims on our car, I should do that. Regardless, this engine runs pig rich quite often to begin with, particularly under load and low RPM, fighting detonation.
 

yugrus

Contributor
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CX-5 GT
It also could be injector or coil connectors. When you rev the engine in neutral it doesn't tilt much. It tilts under load, potentially causing a weak/dirty connection to fail.
 
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Mazda RX-7
It also could be injector or coil connectors. When you rev the engine in neutral it doesn't tilt much. It tilts under load, potentially causing a weak/dirty connection to fail.

The harness is pretty tight to the motor. It's only a 2013. The connectors feel secure and look new.

Unfortunately I cannot do some of the troubleshooting, like turning on and off injectors with HP Tuners. The manual for the SkyActiv-G says to use some "M-MDS" thing which I do not have access to.

This manual
 

yugrus

Contributor
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CX-5 GT
If you have Elm OBD2 dongle, WiFi or Bluetooth, download Forscan, PC version, it can do pretty much same things as OEM scanner, depending on the dongle. Politely ask the author for the license, he normally gives it away for free, for a period of time.
Mobile app is also very useful, and free, everyone who's into Ford/Mazda should have that.
 

Chris_Top_Her

Banned
Moderator
Contributor
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San Antonio, Texas
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'15 CX-5 Miata AWD
Improper operation of ignition system
n Spark plug malfunction
n Ignition coil related wiring harness or connector malfunction
n Ignition coil malfunction
l Fuel injector malfunction
n Improper operation of fuel injector
n Fuel injector related wiring harness malfunction
l Erratic signal to PCM
n CKP sensor signal malfunction
file:////hoth/manuals/cars/mazda/2015/cx5/cx5/am.mazdaserviceinfo.com/emazda/d...ersystem/service/esi/en_us/SM/2015/CX5/pv/books/pvw01/html/id0102h4703300.html (2 of 14)2/24/2014 6:58:52 PM
DTC P0301:00, P0302:00, P0303:00, P0304:00 [SKYACTIV-G 2.0, SKYACTIV-G 2.5]
POSSIBLE CAUSE
n ECT sensor No.1 signal malfunction
n MAF sensor signal malfunction
n MAP sensor signal malfunction
n IAT sensor No.1 signal malfunction
n APP sensor signal malfunction
n TP sensor signal malfunction
n VSS signal malfunction
n Related connector or terminals malfunction
n Related wiring harness malfunction
l Poor drive belt assembly or adhesion of oil
l Drive belt auto tensioner malfunction
l Air leakage from intake air system (between intake manifold and cylinder head)
l Engine malfunction
n Insufficient engine compression
n Engine coolant leakage to combustion chamber
l PCM malfunction
System Wiring Diagram
l Not applicable
Function Explanation
 
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Mazda RX-7
ForScan gave me some new information. I could see the Commanded Fuel Pressure, which I could not see before. So I was able to verify that the Fuel Pressure at the Rail was always in line with the commanded.

I also disconnected the rear O2 since it's actually in front (I know sounds weird) of the rear cat. I wanted to check to see if I had a clogged cat. I figure the extra hole in the exhaust before the cat would give it extra breathing room. However, car still behaves exactly the same.

So I don't believe it is the High Pressure Fuel Pump, Rear O2 sensor, or a clogged rear cat.

Here's a shot where she typical hesitate / misfires / bucks. 20% lean of the command. Like the injectors are possibly slow to react to the demand?
 
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GA prior 16 CX5 GT
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20 CX5 GT + Prem
OP, do you know the history of this car? Has someone replaced the original computer map with a performance one(and introduced some errors)? I see you swapped some parts, can you swap the computer? Checking the temp of the CAT is a good idea, I might try switching the second O2 sensor as well.
 
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Mazda RX-7
OP, do you know the history of this car? Has someone replaced the original computer map with a performance one(and introduced some errors)? I see you swapped some parts, can you swap the computer? Checking the temp of the CAT is a good idea, I might try switching the second O2 sensor as well.

Car behaved the same with the rear O2 in free air.

Car is completely stock. Just a daily driver for my G/F's Dad. I have access to another CX-5 (G/F's brother) but it's hard to align schedules. Everyone needs their car. This CX-5 has been in my driveway for a week now, while he drives our Equinox.

I've considered swapping PCM, Fuel Rail/Injectors, and MAP. I really don't know what else to look for at this point.
 

yugrus

Contributor
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CX-5 GT
LTFT gets out of scale at 23% while spark advance is pulled to zero. It's choking, it can't burn all that fuel, that's what it looks like to me. It behaves like under huge load with no help from the transmission...
Another thought, SkyActiv engines are quite finicky when it comes to spark plugs. I've read that OEM plugs are the part of the system for indirect measurement of the cylinder pressure. I see that you're using Bosch plugs with multiple applications... Who knows...
How did you check for air leaks, did you use smoke machine?

It is a waste to throw parts at the problem, but in your situation there's not too many options.
Too bad there are less and less techs who know what they are doing, even at the dealer. Their hiring pool is the same as Midas'.
 
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Mazda RX-7
I think the timing being pulled is a result of all the knock. As I sweep the graph it starts at 43* and quickly drops.

I don't have access to a smoke machine. I have capped the brake vacuum port and visually triple checked all the hoses. This car isn't very old and the hoses are in good shape.

When I get some time I am going to try and thoroughly go through this procedure. Many I have done already.
http://mazdaman.x10host.com/SM352634/

Wondering if I can shut off injectors with ForScan???
 

yugrus

Contributor
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CX-5 GT
I'm sure I recall shutting injectors off with ForScan on my son's Crown Vic. It was a while ago, I can't recall now how it's done. Shouldn't be too hard. What are you trying to achieve with that though?
 
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Mazda RX-7
I'm sure I recall shutting injectors off with ForScan on my son's Crown Vic. It was a while ago, I can't recall now how it's done. Shouldn't be too hard. What are you trying to achieve with that though?

See if one being shut off has less effect than the others. Maybe another weak injector.

Honestly just swapping the whole rail over from a known good car would be more definitive. I'm nervous about the Teflon seals getting ruined. It requires a special tool to put them back on supposedly.... and they are 12 bucks a piece I think.
 
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GA prior 16 CX5 GT
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20 CX5 GT + Prem
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