35 replies to this topic

[Paul Watts]

Any tips on what to try next??

 

In car video of symptoms:

 

https://www.youtube....h?v=njOqfRS4MWA

 

Initially the car would cut out at wide open throttle (like someone turned off the key) for only a couple of seconds.  Shortly into the session, the cut out gets more frequent and the engine begins to stumble / hesitate at light throttle.  After pumping the gas pedal and shifting the car would “turn back on.” 

 

After this session the MIL (check engine light) was on and the code was P0340 (Mazda code is P1345) – Camshaft Position Sensor Circuit Malfunction.

 

MIL Freeze Frame Data Reads as Follows:

 

Fuel Sys 1…………………….OL-Drive

 

Fuel Sys 2…………………….NA

 

Calc Load(%)……………….77.3

 

ECT(°F)………………………..169

 

STFT B1(%)………………….0.0

 

LTFT B1(%)………………….0.0

 

Eng RPM…………………….6412

 

Veh Speed(mph)………..80

 

Car starts and idles fine.  Issue only manifests on the track.  Car is a 2001 LS with VVT engine. 

 

The following items were replaced / changed and the problem was NOT resolved.

 

1. Camshaft Position Sensor (Brand New)

2. Ignition Coil Packs (Both brand new)

3. Fuel Filter

4. Filled Gas tank to Full

 

 

 

[Keith Novak]

I would go with fuel pump.  They act up at funny times when they start to go.  I sorted this out in my race car this year and then I sorted it out in my tow rig.  There were lots of other theories as to what it was but I'm finding when they fail, they will first do it at specific spots on track under power (or towing up a hill for the rig) and then begin to hesitate from a stop.  They will then return to normal and it's hard to duplicate the problem but they won't get better with time.

[Ron Alan]

Check the actual wiring and plug that goes into the cam sensor. A broken wire or pin contact that shows up when it gets warm with a lot of car vibration?

[Stelvio]

I know this sounds really basic but check the ground wire from the battery. I had a similar issue at Watkins Glen and we went from sensor to sensor changing things out and then found that the ground wire was frayed badly enough that I was losing power intermittently through that. We made an new wire and the problem was solved. Not a likely answer but if it is that you could save yourself a lot of work

[Bench Racer]

This info is well intended.

Plumb a fuel pressure gauge to a location at the cowl so you may view when the enging stumbles. Fuel pressure, yes or no.

With engine runing "slowly" steadly push the accelerator pedal to approx 4,000 rpm and see if there is any hesitation or ossilation to a lower rpm while your foot is continiously on the accelerator pedal. If yes, could be the throttle position sensor.

[David S.]

Mitchell OnDemand says that a crank sensor could cause this code, too. It seems like the computer isn't seeing the proper correlation between the crank and cam sensors. Could be a bad crank sensor, cam sensor, or if it has VVT it could be something getting messed up in that system. Is your oil level ok? I have never worked on a newer Miata but I know low oil will wreak havoc on the Honda VTEC system. With as much as I have read on here of cam sensor failures I'd think that a NIB one could be no good too. If you run out of stuff to try I'd swap it with a known good one off of another car. Good luck getting it sorted out.

[Keith Novak]

Two additional thoughts.  Make sure the code is related to the cut out issue.  They could be two different things so solving the code might not solve the fuel issue.   The other is that an intermittent cut out issue has appeared on the site several times before due to multiple different reasons.  People are always helpful in pointing out what caused their own issue and sure you have the same issue, but that don't make it so.  It's been grounds, bent pins on the ECU harness, loose baffles in the tank, fuel pump, and the list is sure to go on. 

 

Good luck!

[Paul Watts]

Keith, I think you might be onto something with the fuel pump.  Would a fuel pump that is going bad throw a code?  

 

I’ve re-watched the video for clues and well the fuel injectors / fuel pump are definitely getting shut off.  I noticed this from the AFR gauge that reads 22% oxygen when the engine cuts out.  To me, this only seems possible when no fuel is being admitted and the engine begins to pump pure air into the exhaust. The only question now is this from a bad sensor or bad pump.  I think a bad Cam or Crank sensor on the VVT will cause the ECU to cut off power to the fuel pump right? 

 

David / Mitchell you are now the 3^rd opinion I received on the crank sensor. I also found someone else on another forum with a VVT that was getting the P0340 code and it ended up being the crank sensor even though the code is for the cam circuit.  So after seeing the video and hearing multiple people say the crank sensor, I went ahead and put in a new OEM crank sensor.  I figure worse case scenario, I will have a spare now if the problem isn’t resolved.  Hopefully this is it, I’ll report back once I get it out for a drive. 

 

Also, Dave you asked about my oil level.  The oil level is full, but I am running thin 0-20w oil right now.  I suppose it is possible there is not enough oil viscosity / pressure for the oil control valve (OCV) to position the camshaft properly on the VVT.  I’m not sure how the ECU controls this, but I would guess the ECU would not be happy if it commanded the camshaft to a certain position and then the cam sensor reported back to the ECU it was in a different location.   There are separate DTC codes for this, P0011 is for Camshaft over advanced and P0012 is for camshaft over retard.  I did try and test this though; I disconnected the electrical connector to the OCV on the VVT.  Car started and idled, check engine light came on immediately with code P0010: Camshaft Position Actuator Circuit Malfunction.  The car was not reporting any of these codes when I pulled off the track, but I know how that goes codes rarely tell the whole story.  I think if the crank sensor turns up as a bust, I will drain the oil and put in OEM recommended viscosity.  I for one am at least curious if the thin oils will affect the VVT system, sure someone else is too. 

 

Thanks everyone for your input so far!  You have definitely given me some more things to look at.

 

 

[QuattroGuy]

I've been fighting this same issue on my 1999 CA emissions car. Every change I make seems to "fix" the car for a while. Sometimes I'm good for a month, other times a few hours. To give the cliff notes version, I've replaced the cam position sensor, the crank position sensor (both several times), rerouted the CPS wiring, replaced the last few inches of harness to the CPS, and, just this week, replaced the engine control harness all the way back to the ecu. (Not fun with race seats and a cage!)

When my car cuts, the tach drops immediately, even at speed, leading me to believe that my problem is not fuel related, but rather that spark just goes away. My advice is to watch your tach.

I'll report back on the harness swap results.

Oh, one more thing: in the course of my diagnostics, there was a point where I could rev the engine up gradually and watch the frequency of vibration of the wires until I saw the cut at 6k. I could actually see the CPS plug vibrating on the CPS, seemingly producing the cut.

Tom

[KW78]

 

Keith, I think you might be onto something with the fuel pump.  Would a fuel pump that is going bad throw a code?  

 

I’ve re-watched the video for clues and well the fuel injectors / fuel pump are definitely getting shut off.  I noticed this from the AFR gauge that reads 22% oxygen when the engine cuts out.  To me, this only seems possible when no fuel is being admitted and the engine begins to pump pure air into the exhaust.

 

 

 

Actually your logic isn't quite correct.  The Wide band oxygen sensor is sensing oxygen, so it will read full lean for any condition that doesn't combust the oxygen.  So even if you have air/fuel mix going down the exhaust pipe it will sense the oxygen and read 22.  In other words, a no spark misfire will look the same as a no fuel misfire to the wide band.

 

If you are getting a sensor code, typically it is a dropout in the sensor circuit.  Not always is that due to a bad sensor.  I also have seen a cam code when the crank sensor signal was the culprit, so that has something to do with the mazda algorithm  of which problem it is self-diagnosing to set the code.

 

I have a car doing this right now to and it has proven unfixable so far, reliably.  I too will get no symptoms for awhile from a change.  My current working theory is that it is a wiring harness issue, but my next real step is to prove it with a labscope at the ECM.  My main problem is it has to be a hot day, and hitting a bump for the cutout to happen.  

 

The other item to keep in mind is that the 5V refernce signal can dropout too.  Rare, but I have seen it on street cars problems we've seen in the shop.

 

Another big clue is that your tach does not seem to flicker with the symptom.  Not being familiar with the 2001 vvt and not trusting mitchell all that much, I would hold the car at 4000 rpm and briefly unplug the cam and see if the tach dies imediately or tapers down with the dying motor.  Do the same for crank.  See if that defines a circuit that does not effect the tach. 

 

The tach is a generated output from the ECM to the instrument cluster, so the above test may not be the end all be all. 

 

Hope this helps

 

Kyle

 

EDIT:  BTW, these issues are why this class dominated by 15+ year old 100K+ mileage donor cars, needs to allow all wiring and a cheap aftermarket ECM, such as megasquirt.  I litterally may have to retire the SM that I am fighting with on this issue.   This will make for better racing too, as shortly, the best VE and timing maps would be attainable, public knowledge... My 02!

[Keith Novak]

 

Keith, I think you might be onto something with the fuel pump.  Would a fuel pump that is going bad throw a code?  

It certainly can.  When it went out on my truck, it gave me codes related to the O2 sensors.  I realize that's not a 2001 Miata, but depending on the logic in the system, sometimes the codes don't directly relate to the problem itself.  It's a matter of what the sensors are picking up to detect the message and how it interprets that bad signal.

[Joe (dad) Jordan]

Here is what we have learned.  This is shared information from 3 2001's running in SOCAL.

 

The=is camshaft sensor can handle a higher temp than the stock sensor up to 300 degrees,

 

www.rockauto.com/catalog/moreinfo.php?pk=938308    (try cutting and pasting)

 

One 01 ran back to back with stock and this sensor in 100 degree heat at Spring Mountain.  He had no miss when he ran this sensor.

 

We have also resoldered every connection in our 01 engine harnes and gone through each wiring connection.  The sensor connector are know to have freys.

 

Hope this helps

[Todd Green]

The sensor connector are know to have freys.

 

Everyone knows you don't want to mess with the Freys:

 

Just bustin your chops, thanks for the info.

[Joe (dad) Jordan]

Here is another example, this was taken from another forum that is talking about the Miata birthday party at MRLS

 

The usual VVT hickup - cam sensor went out.

Car started cutting bad at part throttle all of a sudden, limped it around until I got back to the garage, instructed my passenger to stay strapped in, jumped out, put a new sensor in 30 seconds and drove right back out with a healthy car.

[Paul Watts]

Joe, haven't had a chance to take the car out, but I got the Airtex sensor you recommended.  The brand new sensor I put in at the track (which didn't work) was one from an O'Reilly auto pats store just down from the track.  The two are stamped with different numbers and visually look slightly different.  I will report back when I give it a try. 

 

Do these things go bad frequently for an 01+ track car?  

[Joe (dad) Jordan]

Joe, haven't had a chance to take the car out, but I got the Airtex sensor you recommended.  The brand new sensor I put in at the track (which didn't work) was one from an O'Reilly auto pats store just down from the track.  The two are stamped with different numbers and visually look slightly different.  I will report back when I give it a try. 

 

Do these things go bad frequently for an 01+ track car?  

 

My understanding is yes.  A group that runs a bunch of VVT's in a different class out here called 949 racing changes them frequently.  Their advise was to change it before every big Race.  I would also suggest re- soldering your engine harness or getting a new one from mazda and soldering it.  Jim Drago has an example of what he has done on this forum somewhere.  Also some believe running the correct oil is very important something to do with sensor design etc.  Not sure on that one...

[QuattroGuy]

New wiring harness solved my issue.

[Paul Watts]

Was just able to take out the car out and for a drive and the issue seems to be solved for now.  We’ll see how it does at the track for a practice day in a couple of weeks.  Items changed were:

 

1. Airtex Cam Sensor  (thanks for the tip Joe)

2. OEM Ignition Wires

3. OEM Crank Sensor

 

Would have been nice to change items one at a time and narrow it down to one, but I didn’t have the luxury.  I’m still suspect of the engine wire harness, so I’m going to get one of those as well, solder it up and have it ready for change out at the track in two weeks. 

[Keith Andrews]

Here is what we have learned.  This is shared information from 3 2001's running in SOCAL.

 

The=is camshaft sensor can handle a higher temp than the stock sensor up to 300 degrees,

 

www.rockauto.com/catalog/moreinfo.php?pk=938308    (try cutting and pasting)

 

One 01 ran back to back with stock and this sensor in 100 degree heat at Spring Mountain.  He had no miss when he ran this sensor.

 

We have also resoldered every connection in our 01 engine harnes and gone through each wiring connection.  The sensor connector are know to have freys.

 

Hope this helps

 

Do you know what the temp spec is for the stock cam position sensor?  I'd be interested in the specs for the stock crank sensor as well if you have it.

[Keith Andrews]

I found this trouble shoot information online for a 2001.  Has anyone used this to work the issue?  The following is from a Mazda technician answering a question about the P1345 code online.  I know throwing a new cam sensor at the car will delay the onset of this problem.  I wonder if it really is just the cam position sensors getting to hot or something more. 

 

_______________________________________________

 

OK, here is the diagnosis pinpoint test for that fault code. Follow it step by step to determine the root cause of your concern. 

I have also seen alternator interference cause this fault code. Disconnect the electrical connector from the alternator and test drive as you did before to make the check engine light come back on. If the code does not come back and engine runs good, replace the alternator. 

I have also seen the incorrect spark plugs cause this concern. Make sure you are running the standard Mazda spark plug and ignition system.

 

2001 - Miata - Workshop Manual - Engine DTC P1345 (or P0340)

 

DTC P1345 (or P0340)

CMP sensor circuit malfunction

DETECTIONCONDITION

 

• Diagnostic support note

• This is a continuous monitor (CCM).

• MIL illuminates if PCM detects the above malfunction continuous during first drive cycle.

• PENDING CODE is not available.

• FREEZE FRAME DATA is available.

• DTC is stored in the PCM memory.

• If PCM does not receive input voltage from CMP sensor while crankshaft 8 rotations, PCM determines that CMP sensor circuit has malfunction.

POSSIBLE CAUSE

 

• CMP sensor malfunction

• Connector or terminal malfunction

• CMP sensor is dirty.

• Open circuit between main relay terminal D and CMP sensor terminal A

• Open circuit between CMP sensor terminal B and PCM terminal 3V

• Open circuit between CMP sensor terminal C and body GND

• Short to GND circuit between main relay terminal D and CMP sensor terminal A

• Short to GND circuit between CMP sensor terminal B and PCM terminal 3V

• CKP sensor malfunction

Diagnostic procedure 

 

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS BEEN RECORDED

 

• Has FREEZE FRAME DATA been recorded?

Yes

Go to next step.

No

Record FREEZE FRAME DATA on repair order, go to next step.

2

VERIFY RELATED REPAIR INFORMATION AVAILABILITY

 

• Check for related Service Bullatins and/or on-line repair information availability.

• Is any related Service Information available?

Yes

Perform repair or diagnostic according to available repair information

 

• If vehicle is not repaired, go to next step.

No

Go to next step.

3

CLASSIFY INTERMITTENT CONCERN OR CONTINUOUS CONCERN

 

• Start engine.

• Is same DTC present?

Yes

Go to next step.

No

Intermittent concern exists. Go to INTERMITTENT CONCERNS TROUBLESHOOTING procedure.

(See INTERMITTENT CONCERN TROUBLESHOOTING)

4

INSPECT POOR CONNECTION OF CMP SENSOR CONNECTOR

 

• Turn ignition key to OFF.

• Disconnect CMP sensor connector.

• Check for poor connection (damaged, pulled-out terminals, corrosion, etc.).

• Is there any malfunction?

Yes

Repair or replace terminal, go to Step 12.

No

Go to next step.

5

INSPECT POWER SUPPLY CIRCUIT AT CMP SENSOR

 

• Turn ignition key to ON (Engine OFF).

• Measure voltage between CMP sensor terminal C (harness-side) and body GND.

• Is voltage B+?

Yes

Go to next step

No

Repair or replace for open circuit or short to GND, go to Step 12.

6

INSPECT CMP SENSOR SIGNAL CIRCUIT FOR OPEN

 

• Turn ignition switch to OFF.

• Disconnect PCM connector.

• Check continuity between CMP sensor terminal B (harness-side) and PCM terminal 3V (harness-side).

• Is there continuity?

Yes

Go to next step

No

Repair or replace for open, go to Step 12.

7

INSPECT CMP SENSOR SIGNAL CIRCUIT FOR SHORT TO POWER

 

• Turn ignition key to ON (engine OFF).

• Measure voltage between CMP sensor terminal B (harness-side) and body GND.

• Is there voltage B+?

Yes

Go to next step

No

Repair or replace harness for short to power, go to Step 12.

8

INSPECT CMP SENSOR SIGNAL CIRCUIT FOR SHORT TO GND

 

• Check continuity between CMP sensor terminal B (harness-side) and body GND.

• Is there continuity?

Yes

Repair or replace harness for short to GND, go to Step 12.

No

Go to next step.

9

INSPECT CMP SENSOR GND CIRCUIT FOR OPEN

 

• Check continuity between CMP sensor terminal C (harness-side) and body GND.

• Is there continuity?

Yes

Go to next step.

No

Repair or replace for open, go to Step 12.

10

INSPECT CMP SENSOR

 

• Check pulsation signal comes out from PCM terminal 3V (harness-side) using voltmeter while cranking engine.

• Is there signal?

Yes

Go to next step.

No

Check camshaft pulley for damage. Replace pulley and go to Step 12.

11

INSPECT CKP SENSOR

 

• Check CKP sensor for following.

• Has above condition been detected?

  • CKP sensor is dirty.

  • Crankshaft pulley is damaged.

  • DTC P0335 is displayed. etc.

Yes

Repair or replace for malfunctioning parts, go to next step.

No

Go to next step.

12

VERIFY TROUBLESHOOTING OF DTC P1345 COMPLETED

• Make sure to reconnect all disconnected connectors.

• Clear DTC from PCM memory using NGS tester generic OBD-II function.

• Start engine.

• Is same DTC present?

Yes

Replace PCM, go to next step.

No

Go to next step.

13

VERIFY AFTER REPAIR PROCEDURE

• Perform “After Repair Procedure”

  (See AFTER REPAIR PROCEDURE)

• Is there any DTC present?

Yes

Go to applicable DTC inspection

(See DTC TABLE)

No

Troubleshooting completed.