the_supernerd

I have a 1987 pickup with a carbureted 22r engine. It has started pinging at about 148,000 miles (it has 155,000 now). It usually starts pinging when the second barrel opens and it is fully warmed up. I posted on this site a few times and have tried all of the suggestions. The advice so far has been great! Here is a list of everything that I have done:

replaced cap/rotor, spark plugs & wires, 02 sensor
replaced air filter
replaced fuel filter
replaced Timing chain & guides
adjusted valves
set initial timing to 0* with vacuum advance plugged
cleaned carburetor with spray carburetor cleaner
checked HAI system
checked EGR valve
tried a tank of Plus (89 octane) gas

I am thinking that maybe the vacuum advance could be haywire, so I would like to know the best way to check that. I also heard that not using genuine Toyota spark plugs can cause pinging, so if anyone has any experience with that then some input would be great. Any other suggestions would be very helpful. Thanks in advance for the input.

Dr. Zhivago

You might want to look at this and this. It sounds awfully familiar to the problem discussed in that write up.

Hope this helps.
G

the_supernerd

That knock sensor tip sounds great, but I do not think my truck has a knock sensor because it is carbureted. Is this correct? I also noticed he replaced his MAF sensor, but I would also not have one of those because that is also a fuel injection component, correct?

Dr. Zhivago

While it is true that you don't have a MAF, if you have an ECU (most likely), you'll probably have knock sensor(s). The ECU controls the timing and spark advance.

Check it out, it can't hurt.

Hope this helps.
G

EDIT: I just double checked and no, the carburetted models do not have knock sensors... Sorry. I spoke too soon.

the_supernerd

Thanks for double checking, have any other ideas?

Plays_with_Toys

I am pretty sure our carbs don't have an ECU, I can't see any in my engine bay.

Have you tried changing your PCV valve? I don't know if that could cause the pinging or not, but its good maintenance anyway. I wish I could help, but carburetors and me go together like cactus and bubble gum(ouch).

Oh check your other thread, I posted a pic to try and help you out there.

Plays_with_Toys

Oops, that one was started by someone else. Didn't look at his name and thought it was you from reading it.


Isn't pinging caused by a lean mixture? Maybe your secondary fuel jet is gummed up and not providing enough fuel for all the air entering???

flecker

your truck has a "sort of ecu" under the driver side dash... a little gray box w/ a plug in it. It controls the emmission and carb crap.
What pinging are you hearing... top end pinging? How did you adjust the valves ie; .008 intake and .012 exhaust? What did the cam look like when you adjusted the valves? How were the rockers? I think your timing w/ vaccum advance plugged should be 5*

the_supernerd

Same here, and I am definetly the gum
I changed the PCV valve when I did most of that other stuff, I forgot about that on my list of parts that I have replaced. :pat: A lean mixture sounds very likely, so I will try cleaning my carburetor some more. My truck has an ECU under the passenger side kick panel. As far as the valves go, I had my mechanic do that. It seemed like he did a good job as far as I can tell.