I just don't think it's that because two afms cause the car to behave the same. Is there some king of cog in the afm that I could trick into putting more fuel in advance the afm's low point by one tooth? I have to smog soon and I think it would be nice to have a wide band O2 to check if it is a lean condition or hot spots in the cylinder head.

 

AFM's are tricky.... tis why manufacturers did away with them ^_^

Electrical-Mechanical Signal at its finest.

 

Well I put a good AFM in mine today and nothing, same problem. I give up, and part this thing out. This has left a very bad taste.........

 

Too bad you're so far away. This would have been a wonderful challenge. Must be something really oddball to be so persistant.

 

If it were by chance the wiring related to the knock sensor, would it be possible to unscrew the knock sensor and then plug it back in? That way it is not detecting anything but it is still communicating with the ECU. You may have to come up with a way to ground it, but I think this would help cancel out the wiring question. Speaking of wiring you say this is a rebuilt/new engine, do you have all of the grounds connected. I know there is at least 8 of them. Sorry if this is redundant..

 

I just remembered that I had an 88 with a similar problem. I ended up having to replace the igniter. I replaced it with one from O'rielly's and it did not fix the issue. So I looked around and found one made my Denso. It actually fixed the problem. I have learned on these trucks Denso electronics are the way to go.

 

Yup, oe denso is the best.

 

Just looked in my thread and saw some posts, Skypilot, sounds like your a pilot, so I'm not that far away. Anyways new AFM did not change anything and I only have a few more tricks up my sleeve. I have just been driving it with the knock sensor unplugged, check engine light on, blah bah blah........Even went as far as driving a couple other 4runners in the 1990-1995 realm and all I can say is that I thought mine sucked......Anyways I will be starting a new revised thread "Part 2" just for fun

Peace

 

Guessing I could make a ground for it and plug the knock sensor wire directly into that, not sure if that is a ground though, it's supposed to pick up an a/c signal correct?

 

Been keeping my eye out for one just for fun!

 

I have a similar issue on my 91 p/u with a 22re. I had the head resurfaced and when I put it back together it would ping all the time. I started running 93 octane gas and it quit, so I just chalked it up to the increase in compression. A few weeks ago I was at a machine shop and was talking to the owner (guy has a ton of experience with many different engines), he said that machining the head on a 22re not only raises compression but also retards the cam timing. The tensioner takes extra slack out of the chain but in the process rolls the camshaft around a little and retards the cam timing in relation to the crankshaft. When you install the chain everything looks right and the links are in the right spot, but the shortened distance between the cam and crank cause them to be out of time with each other when the tensioner is pushing on the chain. He said that increasing compression while retarding camshaft timing work against each other, and in order to fix it he either uses an offset crankshaft key or adjustable cam gear and degrees the cam.

Sorry for the long post, But I didn't see this mentioned and since you said the motor had just been rebuilt, I thought this could be the issue.
-Matt

 

I've had the same problem with my 22RE since I purchased it, I'm the second owner and I have never been able to get rid of it. I'm wondering if it's even possible living here in Phoenix.

I say that cause pinging is related to heat. There's been several times where I have driven to L.A. and the pinging has stopped. The only difference is the ambient temp, I went from 110+ degrees to mid 80's and lower. The truck ran perfect in that environment, especially since I was at sea level too. I have tried everything I could think of. I use 89 octane which helps. Timing is 5 degrees exact BTDC. I clean out the combustion chambers at every oil change, this helps to blow carbon out that leads to pinging. I use the coldest spark plugs I can, NGK V-Groove plugs (Stock # 6427, BPR6EY), this has really helped too. I have a fairly new Denso EGR, all new vac lines but it's still the same amount of ping. I have not checked my fuel pressure but I plan too soon. I'm curious about that. I assume it's pinging but I have not had anyone like a ASE Master engine tech ride with me to tell me "yeah that sound is pinging". I did write to Ted and Engnbldr.com because I have the street RV head. They responded saying that I could possibly have "piston slap" but because of the 89 octane and cooler temps decreasing my problem I'm pretty sure I have pinging.

I have spoken to many header manufactures since I want that as my next mod. I did question one of them if headers reduce cylinder head temps, he said yes. I still have yet to try a header to see if it helps. I'm just not sure if I can ever get rid of this pinging unless I move to a cooler climate.

 

Has anyone suggested putting a o scope on the pin for the Knock sensor going into the CPU while simulating driving conditions?
I have heard the knock sensor cable may send false readings because of age or damage.

 

Have you checked the signal out of the knock sensor itself? Have you checked the signal at the CPU on the pin for the knock sensor? I have read the Gen 1s had problems with the cable.

Just a thought.

 

If you are running lean try this for kicks. in your afm there is a dial that you can lean/richen the mixture. I can't remember which way does what i know lcengineering has stuff on this, and there are a bunch of articles on adjustments. Just mark where stock is and adjust a click or two and see if the pinging goes away. Not sure if this is the best solution but it can hurt to richen it up a little, and it's easy to adjust back.

 

Have not done this, but I have pulled the harness apart and it is solid. Az truck so it had a little bit of dust in there. But I will keep this in mind.

 

I forgot to mention I got the old afm dialed in, engine was running the plugs coco brown. The replacement afm did not have to mess with.

 

Matt, thanks for the long post, I have had the timing anywhere between 0° to 10° and and high octane at the pump and to no avail same systems. If it were a compression issue it would also ping with the knock sensor unplugged which is how I drive it currently. But thanks again for the reply!.

 

Hey Hilux, yours is a bit different as mine will ping no different when it cools off. Yours sounds like EGR related like maybe the the egr gas temp sensor. Thanks for the reply though.

 

I would make two suggestions, make that three, 1 check fuel pressure at idle and at higher RPM's to see if it;s stable, should be about 28PSI. 2. leave pressure gauge attached and pinch off the return line to the tank from the fuel rail pressure regulator, see if that stops fuel pressure drop at RPM's, pressure should rise to about forty some odd pounds. If fuel pressure does not rise after inch off, replace fuel rail regulator. 3.Relocate knock sensor to a lower point on the block by the engine mount bosses, not up high by the head where it is normally located.