PirateFins

Hey guy's found this on another BB and thought some of you might want to read the info about this guy's findings on his pinging problem and how he fixed it on his 22R (E?). He says it might fix the problem for other motors as well. I think I am going to check mine out.

Knock Sensor / Ping fix

Dr. Zhivago

Very interesting read!

G

Dr. Zhivago

Bumping this because it's so cool.

G

Albuquerque Jim

Have you tried it Dr. Z?

Would it retard the timing all the time or just when needed due to ping?

midiwall

If I think I know what I'm saying, the purpose of the knock sensor is to back off on the timing only when there's knocking, and otherwise leave it alone.

So actually.. Depending on the range that the ECU can correct, you should be able to crank the timing into oblivion and let the ECU back it off as required.

Albuquerque Jim

Or, don't mess with the timing and use this as a fix to ping under low rpm/in a high gear. That is only if the knock sensor isn't working properly right now, right?

Dr. Zhivago

Hey Jim,

Mark pretty much said it. But, as for how many degrees the ECU can retard timing, I don't know. I'm sure there is a limit. Probably 20 Degrees or so.

In the article, he mentions being able to run 5 Degrees over the stock initial advance setting without pinging and without changing the fuel grade. Before the fix, he had pinging all the time unless the initial timing was retarded below factory spec, which of course really kills performance.

The point to the article was to illustrate that the poor shielding on the Knock Sensor output wire caused a poor signal to noise ratio (SNR) at the ECU. Improving the ground improved the SNR, which in turn improved performance since the ECU could do it's job much more effectively.

I don't think there are any issues with the Knock Sensors on the 5VZ-FE, but you never know. Maybe it's part of the pinging problem with the SC's. I may tackle this on my engine. Not any time in the next two weeks, but it might be worth checking out all the same. I will probably take a look at the Knock Sensor Waveforms on a scope first before tearing off my intake manifold...

Hope this helps.
G

Albuquerque Jim

So on the 3.4 is the knock sensor hard to get to? I'm not sure where it is even.

Dr. Zhivago

On the 3.4, there are 2 Knock Sensors. One for each bank. They are threaded into the Coolant Passage on top of each bank, underneath the Intake Manifold. So, it is a bit of a chore to get to them.

However, you won't need to remove the Knock Sensors themselves to do the mod, you'll just need to be able to solder a wire to the shield jacket and ground it. You'll still have to yank off the manifold to do it, or in your case, the supercharger, which is probably the only downside.

G

Albuquerque Jim

If I do this mod, is there any potential problem? I don't see any as long as I am careful not to damage the core wire. Even if it only improves the signal to noise ratio for the sensors it is still a benefit, right?

Dr. Zhivago

I don't see any potential problems.

A knock sensor is simply a microphone, or possibly a piezolectric device, that ouputs a waveform that the ECU interprets. Based on the information provided, and if the frequency and amplitude of the waveform are within certain, predefined parameters, the ECU will retard timing if necessary.

Improving the quality of the information provided can only help things I would think.

My .02
G

Dr. Zhivago

One more thing, Jim. If you need an ECU Pinout diagram, let me know.

Peace!
G

DreamToy

OK Im gonna revamp this old thread. I installed a spanking new (reman) Jasper engine in my truck this feb. I dont drive it much but it has been pinging since day 1. I played wiht the timing, ect and saw this post about the knock sensor wire shielding in the ECM wiring harness.

My question is............Has anyone tried this with any success? what did ya find if ya tried it?
Im gonna try it this week....Ill post results if I have the opportunity.

John

Bumpin' Yota

this is a damn good read, i got pinging/knocking when cruising at low rpm high speed....

VAFM is dead btw

YodaTundraTRD

Hey. I think you may have what I am mooking for. If you get this, I could use that ECU pinout. I am working on a fuel computer for my 5VZFE Tundra. If you still have it, email to eldog@maine.rr.com.
Thanks