Misfire saga... Measuring blocks
11-29-2006, 03:54 AM
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Misfire saga... Measuring blocks
OK... It looks like Cylinder 7 is the primary culprit. I ran the measuring blocks and the ONLY thing out of whack is Group 16 - Knock Control Bank 2. There ARE other, random misfires, but nothing consistent. Cylinder 7 misfires quite a bit -- especially when cold -- when you drop from >~2K RPM down to idle, but the misfires lessen as the engine warms up.
The Knock Sensor signal is consistently double the voltage (~1.4V) of all other cylinders at idle. At 2600 RPM (parked), it would sometimes spike up to 20V while the other cylinders were at 2 to 3V. A few times, a couple (or even all) of the cylinders spiked a little bit, but nothing that I recall being over 5V for a moment.
ADDITIONAL NOTES: The battery was completely dead AGAIN -- even though the car had been garaged and not run for a day. Also, the "click... click..." sound from before seems to be related to the brake. I heard it when I applied the foot brake during testing. It also engaged (or maybe disengaged) on its own around 2400 RPM while parked.
NOTE: The fault codes changed to "Misfire... Intermittent" after testing for a while. Also, I gained an ECU Miscoded fault after testing, but that has popped up now and then before and a full ECU diagnostic (at an ECU shop) showed it good.
So... It is headed to the shop in the morning so that they can look at Cylinder 7. They also need to check a brake vibration (they did new rotors/pads <6 months ago), clean out the cowl/evap drains & maybe change the oil (but I might wait until I do seal/gasket work soon).
Thoughts???
The Knock Sensor signal is consistently double the voltage (~1.4V) of all other cylinders at idle. At 2600 RPM (parked), it would sometimes spike up to 20V while the other cylinders were at 2 to 3V. A few times, a couple (or even all) of the cylinders spiked a little bit, but nothing that I recall being over 5V for a moment.
ADDITIONAL NOTES: The battery was completely dead AGAIN -- even though the car had been garaged and not run for a day. Also, the "click... click..." sound from before seems to be related to the brake. I heard it when I applied the foot brake during testing. It also engaged (or maybe disengaged) on its own around 2400 RPM while parked.
NOTE: The fault codes changed to "Misfire... Intermittent" after testing for a while. Also, I gained an ECU Miscoded fault after testing, but that has popped up now and then before and a full ECU diagnostic (at an ECU shop) showed it good.
So... It is headed to the shop in the morning so that they can look at Cylinder 7. They also need to check a brake vibration (they did new rotors/pads <6 months ago), clean out the cowl/evap drains & maybe change the oil (but I might wait until I do seal/gasket work soon).
Thoughts???
11-29-2006, 07:44 AM
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what would you see if the knock sensor was bad? i still have misfires on 7 & 8 and have...
no clue what to try now. I was also gonna check all the connections to the CPs and clean them with CRC electrical contact cleaner, check the wiring to make sure nothing is pinched or cracked. other than that, i have no clue...im at my wits end. help
