2001 Honda CR-V Case Study

Tim Owner/Technician Oregon Posted   Latest  
Case Study
Driveability
2001 Honda CR-V EX 2.0L (B20Z2) 5-spd (SBXM)
P0304 — Cylinder 4 Misfire Detected
Misfire

Honda 2001 CR-V 2.0 Liter DTC P0304 We recently had a 2001 Honda CR-V to diagnose. This vehicle was brought to us from another shop. The concern was that it was setting a P0304, #4 misfire. The scan data showed repeatedly that cylinder #4 was misfiring, even though the engine did not appear to misfire. We connected the scope to the ignition coil #1 and the front CKP sensor. We then checked the crankshaft sensor yellow trace fig 1, the data appeared to be ok. We then ran this data through the CKP misfire system in our ATS scope fig 2. The CKP sensor data showed that cylinder 4 was missing. We then connected a tailpipe pressure transducer to the exhaust tailpipe to confirm the misfire on cylinder 4 fig 3. As you can see the CKP data, yellow trace, showed a misfire occurred on cylinder 4 but the tailpipe sensor, blue trace, showed no misfire occurred on any of the cylinders. We then revved the engine and reran the CKP data on the scope fig 4. It appeared that the crankshaft was changing speeds for a single cylinder. Since this cannot happen we were pretty sure the CKP sensor was loose on the crankshaft. We then looked over a wiring diagram and found a distributor timing sensor. We now connected to this sensor and ran a CKP test fig 5. Now we could see that the distributor signal, green trace, did not have the problem that the crankshaft sensor had, yellow trace. We disassembled the front of the engine to get access to the crankshaft sensor. The video of the loose CKP sensor is shown in fig 6.

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Interesting
Mike Instructor
California
Mike Default
 

Hi Tim, I hope you are doing well----- I know this is off-topic, and I apologize, but can you please send me your e-mail address? The one you gave me a little while ago is getting kicked back to me. Please send it to: … Thanks!

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Eric Owner/Technician
Wisconsin
Eric Default
 

Tim, That crankshaft sprocket is captured between the crankshaft and balancer pulley. Unless the crankshaft balancer bolt was loose I can't see how the crankshaft sprocket would be loose. Even if it was loose why would it consistently affect one cylinder? Do you have it back together and running correctly now? If so could we see some after wave forms? Thanks, Eric

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Benjamin Owner/Technician
Georgia
Benjamin Default
 

I think Eric has a point. Although this engine doesn’t have a balancer shaft. Check valve lash and guides. Also these have 30k ngk plugs.

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Eric Owner/Technician
Wisconsin
Eric Default
 

Benjamin, Not Balance shaft but Harmonic Balancer, you know, the round thingy that attaches to the crankshaft with a bolt and is on the front of the engine, sometimes has a pulley or two on it for the belts. Eric

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Craig Technician
Tennessee
Craig Default
 

Did you do the intake transducer? Worked for Honda when these vehicles were new and this head was bad about sucking valves into the head.

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Rudy Technician
California
Rudy Default
 

Tim- So is this vehicle fixed? Ed is correct,that sprocket is captured, I doubt it would move much,if at all, with the crank pulley bolted in place. Is the key sheared or key way widened?

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Tim Owner/Technician
Oregon
Tim Default
 

I feel really lucky to have great software avalible for my scope from ats. The data does not lie, yes the car is fixed. The neet thing about this car is it had two crank identification, one on the crank and one in the dist. Look at fig 5 the dist green there is no frequency change, the yellow was changing frequency on cyc 4, it changed on several cyc at certain rpm, but look at the green trace…

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Helpful
Dmitriy Analyst
Ontario
Dmitriy Default
 

Thanks for the update, Tim! Is it possible to attach before and after TDMS files as well — I guess they will need to be zipped to be accepted for upload? Thank you in advance.

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Geoff Diagnostician
Hawaii
Geoff Default
 

so, it was the wrong bolt, or was a spacer missing? Also in your write-up you said the sensor was loose, not the gear. I kinda guessed what you meant, but you should edit that to make sense.

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