Engine ping

[RS12Turbo]

For the past couple of summers on 95+ degree days.....I have heard pinging/ detonation under light acceleration/ load....usually around 3500 rpms. I have yet to be able to figure it out.......and last week, I heard it in cold weather. It's enough to throw the detonation sensor code.Any idea on where to start looking?The car is a '95 maxima auto with 161,000. I changed the plugs a couple of years ago from ngk platinums to denso iridiums.....but that didn't fix it. Also replaced the 2 front o2 sensors several years ago before the problem started to Bosch....so maybe this could be the prob...since Bosch o2 sensors suck in Nissans. The cat o2 sensor is still the original....i need to replace all 3 with some ntk'sNo engine modifications other than a "drop-in" panel k&n filter.Any ideas what the prob could be?

[maxhopper]

Check your codes and see if you don't have a knock sensor code. Directions on how to pull the codes, and what the codes mean can be found here. zerothread/56283

[RS12Turbo]

yeah........it does throw the knock sensor code...........I mentioned that above, but I put detnotation sensor instead.............sorry

[maxhopper]

What octane fuel are you using?

[RS12Turbo]

always hi-test since 1995...............91% in Cali, and now 93% down here. Most of the time Chevron, and sometimes Shell.

[maxhopper]

Probably just time for a new knock sensor then.

[RS12Turbo]

mmmmmmmm, the knock sensor detects knock, not create it......right?

[maxhopper]

True, but a non functioning knock sensor will cause the engine to operate at a predetermined set of parameters. That coupled with the high temps you where experiencing, could have caused your ping.

[RS12Turbo]

Ahhh, I see. Is there a way to test the knock sensor on the engine, without pulling it out.....because it looks to be a true pain to get to......plus their not cheap.....so I want to make sure it's bad before blowing the $$$ on a new one.

[maxhopper]

This will show you how to test the sensor.

http://is.rely.net/3-9-2204-l-...g.jpg

[RS12Turbo]

Hey, thanks...........I'll test it and see if it's good.........

[skassamali]

Did you ever find out if the knock sensors were bad? I'm having the same issue in my 03 I35...already replaced the MAF and done the EFI service....have an appt w/ the dealer on Monday..but they've been working on this problem for 1+ years.

[RS12Turbo]

I never tested the knock sensor.......I think I resolved the issue though. My maf finally crapped out on me one night. Had to get towed home I replaced it with a new maf, and it seems to have taken care of the problem......but it's cool outside now, and I was only getting ping on hot days......so I may not know till next summer if it truely went away.

[skassamali]

think it's ok for me to drive my car?

[Q45tech]

Knock sensors are tested by ecu everytime you crank and residual noise is measured and calculated every few rpms as a non knock baseline.

Measuring the resistance of knock sensors is a rough and dirty test as the sensitivity of the microphones changes with heat exposure.

As long as their are no codes on Scanners the system is probably working.

KS replacement has been an every 6-7-8 year exercise on Nissan for 20 years.

[skassamali]

Hi - So warm weather is back and surprise surprise, my engine knock is back. The dealer continues to insist there is no issue as the computer is not throwing any codes back. They have tried 3 different kinds of fuel injection services, along with replacing the MAF. I'm running the car hard in an effort to clear out any carbon build-up, but no luck. I run premium fuel and am using bg 44k every month or so. Help!

[RS12Turbo]

Mine too is back with the warm weather. I'm considering going one step colder with some NGK Iridiums to see if that might help, but am concerned that they might foul out. Anyone experiment with going colder? I've done it with forced induction since I was 100hp over stock, and the plugs burn perfectly clean in that application, but with a N/A bone stock VQ, I wonder if a colder plug would foul, and if it would reduce the ping?

[skassamali]

Why the doesn't the engine throw a code or something? That's what I don't get. If the dealer says they hooked their computer up and nothing came up, i'm thinking cars is technically ok. They kept the car for 3 days trying to diagnose the problem.

[RS12Turbo]

Mine will throw the knock sensor code, which doesn't trigger the check light