thook

Hey all,
I have 92' 4runner with a transplant motor from an '89, rebuilt. We've had a good mechanic working on it to get it running properly, but there are still issues. He's pointing to the knock sensor (from the trouble code) and the fuel press. reg. My questions are: Is there some way to test the KS without pulling the top of the motor down? And does anyone know where to find both of these parts cheaper than at the dealer?
I'm aware that I may have to go ahead and replace the KS, and definitely the FPR. I also intend to replace the KS wire, since it had been spliced. But, the wire won't happen until I have the time to replace the VC gaskets. I just wanted to hopefully assess the KS's condition before I fork out the dough for a new one, and rule it out as the TC culprit til I can replace the wire. May be wishful thinking on my part!
I will do some searching on my own for all of this, but so far I haven't been able to find satisfactory answers on testing the KS.
Thanks in advance.

thook

I've checked out some part sites, but was wondering if anyone has had any experience with these particular companies, good or bad.
http://pa.partsandaccessories.com/pa...se&showdc=true
http://replacement.autopartswarehous...lator&dp=false
http://oem.overnightautoparts.com/pa...lator&dp=false
http://shop.toyotapartstore.com/wiza...28ba321628f675
All offer Bosch; is this brand a good choice for a replacement FPR?

wrenchmonster

A knock sensor can be checked with an oscilliscope (not a scan tool, an actual scope) and by tapping on the side of the block with a hammer.

Usually, like 99.5% of the time, if an FPR is going to fail it's because the diaphragm has broken. Pull off the vacuum line and if you see fuel on the other side the FPR is toast. If it's okay, then your problem is elsewhere.

If your FPR is toast, replace that before the KS. A broken diapraghm in the FPR will cause raw fuel to enter the motor via the vacuum line. Dont' just throw parts at it.

For parts, there are some Toyota parts guys on this forum who will give you a fair deal.

thook

Well, I talked to the mechanic a little while ago and he gave me the readings from the FPR. It was reading at 48 psi unhooked, and 54 installed with motor running. He had indeed found fuel in the FPR weeks ago, so we know it is bad. But, would that cause the trouble code to show up as the KS?
Thanks for the heads up on parts and KS test. We don't have much more money to spare, and the FPR alone is quite a chunk anywhere retail.
I will go ahead and replace the FPR and and run the test, and then see where that gets us. Thanks again.

wrenchmonster

Basic knock sensor circuits are used to retard timing based upon the knock sensor sensing a knock in the motor. I'm not entirely sure as I don't have my repair manuals with me, but I think the circuit doesn't have any monitoring. That is, I don't think the ECM actually monitors the knock sensor in and of itself, I think it just knows when the knock sensor cannot compensate for knocks. In other words, when the knock sensor is esentially "out of range".

That said, I'd certainly run down any condition that can cause knocks... ignition timing, valve train, misfires, etc.

thook

There are no knocks, save one very slight tap in the valves. It is very minor. The mechanic said you were right about the test, although he stated that the KS is just not giving a signal. In which case, the oscilloscope wouldn't do much good. That is if I understand him and am relaying what he said correctly. He is going to do some research on the testing.
I posted an ad in the marketplace for a FPR. Can you suggest any way else to make my need for one known here at YT?

^VooDoo^

What happens if the FPR just doesnt open?, How do you think that affects the engine?

thook

Well, I'm not a mechanic, but logically I would guess there would be no fuel pressure.

wrenchmonster

I've never seen a FPR fail in this manner. If it doesn't open then no fuel would be allowed to return to the tank, pressure would spike on the delivery side. Hence, I'd assume that your fuel pump would burn up. Other than that, you could damage your injectors, and maybe create a couple other fuel pressure issue problems.

thook

Been doing some research on KS testing. Given that all I have is an OM meter, would it be just as effective to test the KS once removed for continuity by tapping it? It was suggested by one mech that this is a workable method, but another questioned what the resistance readings would be? Anyone have an idea of what those readings should be? I would like to be able to use the OM meter because it something I could do at home without paying the mech.
Also, is the KS wire coaxial? It doesn't seem to be, and the dealer says that it isn't, but I've heard conflicting info from other sources. Just trying to clarify this little issue to rule out electro interference causing the computer to throw a code.
Note that I have no experience with this kind of thing, so I am aware that I may be compicating things and be getting "too much" input, if you know what I mean. Hell, I just want to know if my KS is bad.

Justin311

Here I will copy/paste a response I just gave in another thread:

Honestly I was not aware that the 22RE had a knock sensor (and I'm not sure why it needs one?)....I'm sure the 22RTE has one, but usually knock sensors are only needed on forced induction engines where the control strategy is to advance the ignition timing until you get knock, then reel it back in a degree or so. A properly tuned NA motor usually doesn't experience knock even on standard grade gas. If it was my 20 year old non-turbo truck I would not even replace it. They are usually fairly spendy at Toyota (~$150). If you want a budget replacement I have a source for knock sensor adaptors which let you thread a cheap ($30) GM sensor back in its place.

thook

Thanks Justin311! I will get with you if I find that I need a new one. This project of tearing the top down to do this and the VCG's will not happen for a few more weeks, though.
One more thing, how much is the adapter?

Justin311

I can get you a whole kit with the GM flying lead and all for pretty cheap. I will call the vendor on monday.

What part of NW Arkansas you in? Im in Fort Smith, headed up to Rogers tomorrow for a car show

thook

Winslow!!!!!!!!! Howdy neighbor!