[alexsmithfanning]

Hello everybody,

I am seeking assistance with a intermittent engine stumbling and lurching on my 2003 Honda CR-V with approximately 300,000 miles. I have had the issue since I got the car about 3 months ago. The issue occurs between approximately 1000 RPM and 3500 RPM. The problem is present under various conditions, including in neutral and under load, and is much more noticeable at lower speeds to the point of being jarring, but is also noticeable on the highway as a vehicle shudder. This is NOT the same issue as when the VTEC spool valve/solenoid fails. I am able to go to any RPM just fine.
The following parts and diagnostics have been completed:

• Replaced:
  • Fuel pump (not OEM but didn't make a difference)
  • All fuel injectors
  • Spark plugs
  • Ignition coils
  • VTEC spool valve/solenoid (not OEM, but it did have P2646 and the power cutting before I replaced it as it was bad, seems to be working fine now)
  • VTC solenoid
  • Both strainers (VTEC and VTC)
  • I have an O/2 sensor spacer installed in the cat to prevent a P0420 check engine light for low catalyst performance
• Checked:
  • Vacuum/smoke test performed with no leaks found.
  • Engine oil level and condition. Oil filter is Honda OEM and oil is Valvoline Restore & Protect 5W-20, and both have less than 1,000 miles on them.
  • Valves have been adjusted into spec (they were already in spec, actually).

Live data from a bi-directional scan tool was monitored during a stumble, and the following was observed:

• The Air/Fuel Ratio data goes wonky when this happens.
• The Manifold Absolute Pressure (MAP) value goes wonky as well.
• Throttle position is working properly.
• Coolant temperature sensor is working properly.
• Crankshaft position sensor is working properly.

During these events, the following camshaft position data was recorded:

• The "CMP Control Command" remained steady and within normal ranges.
• The "CMP Control" (actual value) was observed to be drastically different from "CMP Control Command" when the hesitation occurs.
• The VTC solenoid duty cycle simultaneously drops to zero momentarily before it kicks back on again and tries to adjust

The live data indicates a significant discrepancy between the commanded and actual camshaft position. The VTC strainer was found to be clogged, but its replacement did not resolve the problem. The intermittent and frequent nature of the issue has not activated the Malfunction Indicator Lamp (Check Engine Light). I suspect that it could possibly be a VTC actuator, but at this point I am not sure. I do not know the last time the timing chain was done. I have ordered a camshaft position sensor to see if that might help, but I am not hopeful.

The engine has been well cared for as far as I know. Oil changes on time and all that.

I have attached a video of data playback on my scan tool. You can tell when the issue happens because there will be a drop in RPM, but you have to watch closely. Sometimes it's way more obvious than others. This is in neutral, no load on the engine. I am slowly increasing throttle as smoothly as I can, up to above 4K RPM where everything smooths out because VVT turns off.



Thank you to anyone that can provide some assistance.

 

[otto888man]

the spark plug spacer you installed are these spark plug defouler?
did you installed them in both 02 sensors?
did you installed the spacer in both of the 02 sensors for only the downstream?
try unplugging the front or upstream 02 sensor & try to rev it in neutral & see if you still get the chugging.
are the o2 sensors still oem?

 

[alexsmithfanning]

the spark plug spacer you installed are these spark plug defouler?
did you installed them in both 02 sensors?
did you installed the spacer in both of the 02 sensors for only the downstream?
try unplugging the front or upstream 02 sensor & try to rev it in neutral & see if you still get the chugging.
are the o2 sensors still oem?

Yes, technically it's a "spark plug defouler". I only have it installed on the downstream sensor. Installing one on the upstream A/F ratio sensor would cause many issues, yes? The upstream sensor is the one that is used for fuel delivery, downstream is for the cat only.

The downstream sensor appears to have been replaced, but the upstream sensor seems to be original. I have not tried unplugging it to see if that helps. I will do that after I get off work today.

I can take more data recordings as well, but my scan tool limits custom PIDs to 8, so I can't show any more than that at once without showing them all, which wouldn't be much help.

 

[otto888man]

you are right.
only install it in the downstream,
never on the upstream.
for that mileage most likely the upstream 02 sensor, more appropriately called Air Fuel Ratio sensor.
just in case if it needs the Upstream sensor be sure you only install an NTK brand or a Denso brand no other brand will work properly.
also be sure its an Air Fuel ratio sensor not 02 sensor, as the connector is exactly the same.
good luck
please let us know the fix

 

[Kpnitrunnin25]

Fuel Pump Relay? Have recently read on a similar problem that led to that.

 

[alexsmithfanning]

Fuel Pump Relay? Have recently read on a similar problem that led to that.

I can check that as well. I'll swap it with another relay to see if that makes a difference.

 

[alexsmithfanning]

Swapping the relay didn't have any effect, unfortunately.

 

[alexsmithfanning]

you are right.
only install it in the downstream,
never on the upstream.
for that mileage most likely the upstream 02 sensor, more appropriately called Air Fuel Ratio sensor.
just in case if it needs the Upstream sensor be sure you only install an NTK brand or a Denso brand no other brand will work properly.
also be sure its an Air Fuel ratio sensor not 02 sensor, as the connector is exactly the same.
good luck
please let us know the fix

Unplugging the A/F ratio sensor made the stumbling go away, but it also seemed to disable the VVT system while it was unplugged. I tried a new A/F ratio sensor after that and it didn't make a difference.

 

[otto888man]

what brand of new A/F sensor did you use?

 

[alexsmithfanning]

what brand of new A/F sensor did you use?

I didn't get it from Amazon obviously, but this is the one I used.

Amazon.com: Denso Air/Fuel Ratio Sensor - 234-9005 (Fits Select Years of Honda: Civic/CR-V and Acura RSX Vehicles) : Automotive

Buy Denso Air/Fuel Ratio Sensor - 234-9005 (Fits Select Years of Honda: Civic/CR-V and Acura RSX Vehicles): Oxygen - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

a.co

 

[otto888man]

i see.
there are a lot counterfeit out there.
after installing the new A/F sensor i would suggest to take out the battery terminals for 15 mins. to have the system to reset.

 

[alexsmithfanning]

i see.
there are a lot counterfeit out there.
after installing the new A/F sensor i would suggest to take out the battery terminals for 15 mins. to have the system to reset.

I got mine from AutoZone, which I would assume would be genuine.

I didn't remove the battery terminals, but I did do an all system code clear, which essentially does the same thing.

 

[otto888man]

have you downloaded the repair manual in the 2nd Gen section to help you with your diagnosis.
is the VTEC assy. a good quality?

 

[alexsmithfanning]

have you downloaded the repair manual in the 2nd Gen section to help you with your diagnosis.
is the VTEC assy. a good quality?

I don't really need the repair manual, I have full access to DirectHit Identifix. That's what has gotten me this far.

VTEC assembly is a Doorman unit.

 

[otto888man]

i understand.
i see, Dorman it's a

might be the Dorman causing the issue.

 

[Avisitor]

Just wondering, ...
How do you know the throttle position sensor is working right?? You said it is intermittent?? If you had an oscilloscope then you could monitor the throttle position sensor while driving. Graphing it to see if there is a drop out when the car hesitates?? Nevermind me. I don't know what I am talking about.

 

[alexsmithfanning]

Just wondering, ...
How do you know the throttle position sensor is working right?? You said it is intermittent?? If you had an oscilloscope then you could monitor the throttle position sensor while driving. Graphing it to see if there is a drop out when the car hesitates?? Nevermind me. I don't know what I am talking about.

I can graph it with my scan tool, and I've never seen the throttle position sensor read anything other than what it's supposed to. It's a smooth line from closed to wide open throttle, and never deviates.

 

[Dave J]

I would look at live misfire data maybe a coil failing or an injector more likely a coil this is a weird one interested to see what you find, In neutral not sure if it would look normal I would have to go out and look maybe tomorrow night