Knock sensor codes
11-16-2007, 10:16 PM
#1
Knock sensor codes About a week ago I had three codes: MAF, KR sensor, and one other sensor. I checked the engine sensor fuse and it was OK. Reset the codes and they stayed away. The MAF code isn't critical as I have it physically installed but I'm running OLSD.
I've been getting some constant KR while logging and I'll be putting some race gas in this weekend to see if it disappears. But today the MAF code came back as well as two knock sensor codes. IIRC the codes are P0325 & P0327. The knock sensors were both new this past July when we built the motor on a stand.
I guess I'll see if the wiring is pinched this weekend, but any other ideas?
I've been getting some constant KR while logging and I'll be putting some race gas in this weekend to see if it disappears. But today the MAF code came back as well as two knock sensor codes. IIRC the codes are P0325 & P0327. The knock sensors were both new this past July when we built the motor on a stand.
I guess I'll see if the wiring is pinched this weekend, but any other ideas?
11-19-2007, 08:14 AM
#2
I measured the resistance between the knock sensors and the pins at the end of the harness, and they were both 100Kohm, which fell right in the middle of the 93-107Kohm range dictated in the Helms manual. I measured the new harness I bought and it measured the same. I installed the new harness as the rubber seals fit much better.
I measured the voltage registered on the knock sensors when tapping on the ridge at the top of their hole. The back sensor was registering .001-.003, so it looks like that one is fine. The front sensor would not register anything so I replaced it, but the replacement wouldn't register any voltage change either
The manual indicates these codes are only triggered up til 3000RPM, and also that the computer 'learns' the frequency range of the motor. If the responses are out of this range, and within other specific parameter ranges, then it sets the code. If it learns the frequency range, why do we need to alter the sensitivity of the knock sensors on occasion?
Also, I still get the P0332 code after replacing the harness, and the front sensor. The rear sensor was showing a voltage change from the noise, which indicates it is good, but the code indicates the rear sensor. A friend says he gets the code whenever he goes over 6000RPM and suggested desensitizing the knock sensors. But I've read elsewhere that the P0327 & P0332 codes are hardware malfunctions.
So where do I go from here?
I measured the voltage registered on the knock sensors when tapping on the ridge at the top of their hole. The back sensor was registering .001-.003, so it looks like that one is fine. The front sensor would not register anything so I replaced it, but the replacement wouldn't register any voltage change either
The manual indicates these codes are only triggered up til 3000RPM, and also that the computer 'learns' the frequency range of the motor. If the responses are out of this range, and within other specific parameter ranges, then it sets the code. If it learns the frequency range, why do we need to alter the sensitivity of the knock sensors on occasion?
Also, I still get the P0332 code after replacing the harness, and the front sensor. The rear sensor was showing a voltage change from the noise, which indicates it is good, but the code indicates the rear sensor. A friend says he gets the code whenever he goes over 6000RPM and suggested desensitizing the knock sensors. But I've read elsewhere that the P0327 & P0332 codes are hardware malfunctions.
So where do I go from here?
11-21-2007, 12:31 AM
#3
Since my last post, the codes went away but I was still getting knock. So I threw in 5gal of 104 and proceeded to desensitize the global gain table. I just kept chasing my tail. I maxed out the table and I'd still get knock. So I reset the table back to stock and filled up with 92 octane .
A friend and I went through the diagnostic procedure outlined in the Helms manual. No problem found with 3 sensors (1 spare) nor the harness. No wiring problems between the PCM and the harness behind the intake. The only thing we couldn't try is swapping PCM's, but we did remove the PCM connectors to test the wiring.
It did look like the harness may have been wedged between the RTV and the bottom of the intake, but it tested fine with the intake off. We cut a path through the RTV for the rear sensor to slip through and used a combination of RTV and electrical tape to encourage the wiring to stay put.
Started the car and it died as I backed out, like something interrupted the power to the vehicle. Pulled it back in and heard some knock coming from bank 2, checked the oil level and it was maybe 1.5qts low, from a fresh 6qt fill 700 miles ago. We only had a combined 1/2qt to add, but we added it.
Car died spontaneously again, with the dash lights all flickering off and back on at once, maybe a mile down the road. Broke out the trouble light and notice the #2 injector harness was not snapped on. Drove it gently for a few miles without incident, and then it recurred just before the interstate entrance ramp. Drove back to his house and we looked things over and all looks OK. The audibleknock from bank 2 was gone, presumably due to the #2 injector.
With severe trepidation, I drove it home 30 miles. I just set the cruise control at 65 and kept the throttle changes mild. Seemed to be idling a bit on the high side. Oil pressure rose with RPM's. Battery voltage was OK and steady(although I see the battery leaked some acid about a month back when the alternator was overcharging).
I get within a couple miles of home and the lights flicker off and on again but the car doesn't die. It happened at the same time I hit a bump, but I hit more bumps after that and nothing happened. I finally get home and the dipstick reads mid-has after letting it sit for maybe 15 minutes. I add anothe 1/2qt.
Right now I'm very curious what is causing the intermittent electrical(?) problem. The symptom wasn't there on the way up. I made changes to the VE before the trip back, but nothing else. I'll be paranoid for a few days.
A friend and I went through the diagnostic procedure outlined in the Helms manual. No problem found with 3 sensors (1 spare) nor the harness. No wiring problems between the PCM and the harness behind the intake. The only thing we couldn't try is swapping PCM's, but we did remove the PCM connectors to test the wiring.
It did look like the harness may have been wedged between the RTV and the bottom of the intake, but it tested fine with the intake off. We cut a path through the RTV for the rear sensor to slip through and used a combination of RTV and electrical tape to encourage the wiring to stay put.
Started the car and it died as I backed out, like something interrupted the power to the vehicle. Pulled it back in and heard some knock coming from bank 2, checked the oil level and it was maybe 1.5qts low, from a fresh 6qt fill 700 miles ago. We only had a combined 1/2qt to add, but we added it.
Car died spontaneously again, with the dash lights all flickering off and back on at once, maybe a mile down the road. Broke out the trouble light and notice the #2 injector harness was not snapped on. Drove it gently for a few miles without incident, and then it recurred just before the interstate entrance ramp. Drove back to his house and we looked things over and all looks OK. The audibleknock from bank 2 was gone, presumably due to the #2 injector.
With severe trepidation, I drove it home 30 miles. I just set the cruise control at 65 and kept the throttle changes mild. Seemed to be idling a bit on the high side. Oil pressure rose with RPM's. Battery voltage was OK and steady(although I see the battery leaked some acid about a month back when the alternator was overcharging).
I get within a couple miles of home and the lights flicker off and on again but the car doesn't die. It happened at the same time I hit a bump, but I hit more bumps after that and nothing happened. I finally get home and the dipstick reads mid-has after letting it sit for maybe 15 minutes. I add anothe 1/2qt.
Right now I'm very curious what is causing the intermittent electrical(?) problem. The symptom wasn't there on the way up. I made changes to the VE before the trip back, but nothing else. I'll be paranoid for a few days.
11-21-2007, 09:14 AM
#5
I checked the ground which comes down the front of bank 2 and it was not touching the header. If the starter ground is elsewhere, I didn't check that. I've already had it towed to the dealer. Unfortunately the knock codes aren't set right now so I didn't mention that to them.
