Joseph Harlow

To Start: I'm driving a 2008 Acura TL Base model w/ NAV. 147,000 miles on it and it appears that some things were replaced at the 120k but not the most important things like CAM/Crank shaft position sensors, 02 Sensor, coil pack/spark plugs, etc. I've started to go through the car with my mechanic but I would like to try and knock some of the steps of troubleshooting this issue myself, to save me a lot of money and a lot of back and forth with him.

I was able to pull a lot of information from the ZR15 ODB2 reader I used to scan DTC, but dont know where I can find what these readings should look like when the car is running at optimum performance.

Backstory: I've had issues with the car since I purchased it several months ago and have gone through 3 mechanics before finding someone I can trust. While I'm going to end up having him troubleshoot and fix the major issues. The ones that I can fix myself.(spark plugs, coil replacement, O2 sensors, etc.) I would like to do what I can to save money. I'm about to go pick up a new set of NGK Laser Iridium spark plugs and begin there, but my mechanic is saying he doesn't believe it's the issue and wants me to wait. I would like to see what the guru's here think before I see him again on Monday. I have all the tools to replace the coils, spark plugs and clean the manifold and EVAP cylinder.

I've had misfire's and spark plug/coils going bad on different cylinders and i'm just tired of bringing the car in, waiting to get it back and then only to find that it continues to happen. I drive it for a week or two after they replace a coil/spark plug and as soon as i'm doing 80Mph or higher on the freeway it throws a misfire code again and sputters to the point of forcing me to drive it under 40Mph and not exceeding 3k RPM's to avoid CEL flashing on me. This time it stayed solid as long as i followed those steps and then today all of a sudden the CEL wasnt on when I started the car and it's not idling rough and I also dont feel it sputtering as bad but it's definitely driving more rough than when I got it back from this last stop at the auto shop.

Any help is appreciated greatly and I respect the expertise and knowledge from all of you!

SO here is all the info that I was able to get off the ZR15 - (Harbor Freight Tools ODBII reader that will be released soon that should be around $200)

DTC Codes
1. P0304 - Misfire on cylinder 4. It was 5 and 3 before.
2. P0325 - Knock Sensor Circuit Malfunction
3. P0302 - Misfire on Cylinder 2
4. P0300 - Random Misfire

Suggested issues:
*Faulty Spark Plug
*Faulty Ignition coil
*Faulty fuel injector
*Faulty Fuel pump and/or regulator
*Poor connections or loose terminals at the ignition coil, the injector, and the PCM
*"Open" or "Short" circuit between the ignition coil and under-hood fuse/relay box
*"Open" or "Short" circuit between the PCM and the ignition coil
*Internal Engine Problem
*Incorrect PCM Idle learn procedure
*Incorrect CKP pattern learn procedure
*MAF Sensor

Performance Readings from the scanner:
*calculated LOAD Value: 74.1%
*Engine Coolant Temp: 190F
*Short Term Fuel Trim Bank 1: 3.9%
*Long Term Fuel Trim Bank 1: 3.1%
*Short Term Fuel Trim Bank 2: 3.1%
*Long Term Fuel Trim Bank 2: 2.3%
*Intake Manifold Absolute Pressure: 22(inHg)
*Eng RPM: 2059
*Veh Speed: 35(mph)
*Ignition Timing Advance #1 Cylinder 18.5(°)
*Intake Air Temp: 104(°F)
*Absolute Throttle Position: 25.5(%)
*Run Time: 127 (SEC)
*Commanded EGR: 36.1(%)
*EGR: 0.0(%)
*Command EVAP 91.8(%)
*Fuel Level: 59.6(%)
*Barometric Pressure: 29(inHg)
*Control Module Voltage or ECU Volts:14.050(V)
*Absolute Load Value: 71.8(%)
*Commanded Equivalence Ratio: 1.000
*Relative Throttle Position: 19.6(%)
*Absolute Throttle Position B: 40.4(%)
*Accelerator Pedal Position D: 34.9(%)
*Accelerator Pedal Position E: 16.9(%)
Commanded Throttle Actuator Control: 21.2(%)

sparc

bad knock sensor?

Joseph Harlow

Thats what the mechanic thought initially as well. He quoted me $450 to change that out. That seems high but then I looked into replacing it myself and it involves getting almost all of the top end off to do it.

My dad thought Crank/Cam shaft position sensors, which dont look TOO terrible to replace, but i dont want to put money in replacing things that I could spend in things I know for sure need replaced. Motor mounts for example.

Also, does any one have the experience to know at what cost or at what number of repairs would it make sense to just purchase a rebuilt J engine and scrap ideas of repairing the current one? I've seen some places sell rebuilds for $800-$1000. Then labor for installing, id imagine another $400-500. So $500-700 of repairs, plus possible future issues could easily hit that number.

Thoughts?

El_Cheapo

Have you tried clearing the codes and see which comes back first?

The flashing CEL light indicates a damaging cat misfire. In my experience it is due to unburned fuel so your O2 will read a rich condition for that bank. Honda's misfire counter can be misleading because one bad injector/coil can give you misfires in other cylinders.

I would scope the coils and the injectors to see which one is missing. My suspicion is that something abnormal is happening with the coils. Did you use OEM coils? Why did you have to replace them in the first place? How did you get to that conclusion? Any visual damage?