Had an interesting one come into the shop today.......On my second day of being open for business in my own shop, This vehicle is owned by a used car lot I've never done business with before but was referred to me by another car lot that's my biggest account. I definitely wanted to score another account if possible!
*2007 Honda Pilot with the VCM J35Z1 with @ 90,000 miles.
*P0522 (Engine Oil Pressure Sensor Voltage Low) set....Permanent & History. Resets right after clearing the codes.
According to the owner of the lot, It has been to three different shops so far & have replaced.....
*Oil & Filter.
*VCM manifold which includes the VCM Spool Valve, VCM Solenoid, & EOP Sensor.
*Oil Pressure Switch (For the idiot light)....No idea why it was changed.
*PCM.
I guess someone was convinced it was a wiring issue after the parts cannon approach didn't work, The harness is completely naked & has cut/pulled back insulation on several circuits. I can't believe a seasoned mechanic would be so intrusive while testing circuits.....I'll snap some pics of that tomorrow!
Started out buy probing the 3 circuits at the VCM EOP Sensor, With the insulation pulled back on all 3....Might as well probe them there instead of back-probing!
KOEO, Sensor plugged in.......
*Good ground.
*Good 5-volt reference.
*Signal circuit was in fact low, .006vdc.....Which is a short to ground in my opinion.
KOEO, Sensor unplugged......
*Good ground.
*Good 5-volt reference.
*Signal circuit is now at 5vdc.....This is a Bias Voltage fed out from the PCM through a resistor, Taken with my Vantage Pro. Most cheaper/low impedance DVOM's will affect this voltage reading & knock the voltage down by half or more!
The aftermarket (Dorman) EOP sensor is internally shorted to ground, Priced a Genuine Honda/Denso part @ $240.....The customer was reluctant but Ok'd it after my little rant about aftermarket parts.
Torqued the sensor down & made sure no circuits were crossed/shorted by the hack job on the wiring.
This is where it gets interesting.......
*Cleared the code, Started it up....After @ 30 seconds, Check engine light pops on & the engine starts running on 3 cylinders.
*P2647 VTEC System Stuck On (Which is actually the VCM system) is now set.
If I've learned anything from all the years diagnosing problems like this....The last thing you want to do is get angry or lose your cool, Because it ALWAYS comes down to simple things!
I pretty familiar with VCM J35's & really can't believe Honda would do this to such a good base engine design but thats another discussion. It works on the same principle as a true VTEC but has circular secondary lobes to keep the valves closed during VCM operation.......
*The first clue was the engine was hitting on all 6 before I changed the EOP sensor, That tells me the VCM Solenoid IS NOT stuck on!!! In fact (As a waste of time).....I put the old EOP sensor back on & it hit on all 6 & reset P0522.
*The EOP sensor is suppose to have oil pressure present in 6 cylinder mode & doesn't have oil pressure when in 3 cylinder mode.......Spool valve shifted by the VCM Solenoid.
*Adapted my mechanical oil pressure gauge to the sensor port, Plugged in the defective EOP.......NO oil pressure present with the engine purring away on all 6 cylinders.
I thought to myself.....That's Effing impossible!! Unless something is physically blocking the oil feed to the EOP?
Went a step further, Again it hindsight it was a waste of time......I put 30 psi of regulated air pressure to the Denso EOP (Connector plugged in), With the oil pressure gauge still hooked up.
Started the engine up......NO codes, And the engine ran on all 6 cylinders with zero pressure at the EOP port. The EOP is NOT getting a oil pressure & EVERYTHING else has checked out!
Pulled the VCM manifold assembly & disassembled it........
The EOP port was not drilled through to the spool valve! Thanks Dorman for your JUNK Chinese crap.....I love having to explain to a customer that not only was the sensor faulty but the manifold was never fully machined!
Took a .093" drill bit & drilled through to the Spool Valve.....Fixed it!!!
*2007 Honda Pilot with the VCM J35Z1 with @ 90,000 miles.
*P0522 (Engine Oil Pressure Sensor Voltage Low) set....Permanent & History. Resets right after clearing the codes.
According to the owner of the lot, It has been to three different shops so far & have replaced.....
*Oil & Filter.
*VCM manifold which includes the VCM Spool Valve, VCM Solenoid, & EOP Sensor.
*Oil Pressure Switch (For the idiot light)....No idea why it was changed.
*PCM.
I guess someone was convinced it was a wiring issue after the parts cannon approach didn't work, The harness is completely naked & has cut/pulled back insulation on several circuits. I can't believe a seasoned mechanic would be so intrusive while testing circuits.....I'll snap some pics of that tomorrow!
Started out buy probing the 3 circuits at the VCM EOP Sensor, With the insulation pulled back on all 3....Might as well probe them there instead of back-probing!
KOEO, Sensor plugged in.......
*Good ground.
*Good 5-volt reference.
*Signal circuit was in fact low, .006vdc.....Which is a short to ground in my opinion.
KOEO, Sensor unplugged......
*Good ground.
*Good 5-volt reference.
*Signal circuit is now at 5vdc.....This is a Bias Voltage fed out from the PCM through a resistor, Taken with my Vantage Pro. Most cheaper/low impedance DVOM's will affect this voltage reading & knock the voltage down by half or more!
The aftermarket (Dorman) EOP sensor is internally shorted to ground, Priced a Genuine Honda/Denso part @ $240.....The customer was reluctant but Ok'd it after my little rant about aftermarket parts.
Torqued the sensor down & made sure no circuits were crossed/shorted by the hack job on the wiring.
This is where it gets interesting.......
*Cleared the code, Started it up....After @ 30 seconds, Check engine light pops on & the engine starts running on 3 cylinders.
*P2647 VTEC System Stuck On (Which is actually the VCM system) is now set.
If I've learned anything from all the years diagnosing problems like this....The last thing you want to do is get angry or lose your cool, Because it ALWAYS comes down to simple things!
I pretty familiar with VCM J35's & really can't believe Honda would do this to such a good base engine design but thats another discussion. It works on the same principle as a true VTEC but has circular secondary lobes to keep the valves closed during VCM operation.......
*The first clue was the engine was hitting on all 6 before I changed the EOP sensor, That tells me the VCM Solenoid IS NOT stuck on!!! In fact (As a waste of time).....I put the old EOP sensor back on & it hit on all 6 & reset P0522.
*The EOP sensor is suppose to have oil pressure present in 6 cylinder mode & doesn't have oil pressure when in 3 cylinder mode.......Spool valve shifted by the VCM Solenoid.
*Adapted my mechanical oil pressure gauge to the sensor port, Plugged in the defective EOP.......NO oil pressure present with the engine purring away on all 6 cylinders.
I thought to myself.....That's Effing impossible!! Unless something is physically blocking the oil feed to the EOP?
Went a step further, Again it hindsight it was a waste of time......I put 30 psi of regulated air pressure to the Denso EOP (Connector plugged in), With the oil pressure gauge still hooked up.
Started the engine up......NO codes, And the engine ran on all 6 cylinders with zero pressure at the EOP port. The EOP is NOT getting a oil pressure & EVERYTHING else has checked out!
Pulled the VCM manifold assembly & disassembled it........
The EOP port was not drilled through to the spool valve! Thanks Dorman for your JUNK Chinese crap.....I love having to explain to a customer that not only was the sensor faulty but the manifold was never fully machined!
Took a .093" drill bit & drilled through to the Spool Valve.....Fixed it!!!
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