Ijust replaced my water pump and timing belt and have the exact problem. The water pump seized so I thought it may be a cracked head or burnt valve. ran great till i replaced the pump and belt. Revvs great till under load. And as the engine warms the knock and ping increases a bit. would it still run if I was off one tooth on the cam gear? is that maybe the problem.

 

It would run if it were off one tooth, The first time I did a timing belt I did not set it right, it was off like 3 teeth - and good thing it was a non interference engine!! but it ran, but very rough.
I'm still trying to figure out my spark knock problem, and with the weather getting warmer, its getting worse. I took the timing cover off and all of the marks still line up perfect every complete cam rotation.
haha - time for an engine rebuild I guess - or just pull the heads and clean carbon...

 

I figured it out. It was a leaky head gasket that happened when the water pump seized and the engine got hot. Blew out a week ago. Wish I had a 4banger right about now.

 

try running 87 grade fuel and see if it stops. 93 is not recomended by these toyotas. you should be running 87.....

 

yeah - I put 87 in and it pings its rear end off!

 

Sounds exactly like what mine was doing. It was the head gasket on mine. Check ur compression after in warms up. You will probably find ur answer there

 

My 89 had a persistent pinging problem for over 10 years that also didn't care what octane I burned or where I set the timing. I checked everything (or I thought I had). Even after I changed the head gaskets in 2001, it was STILL pinging. I finally gave up looking.

Two and a half years ago, I replaced the distributor because the bearings/bushings were squealing when it got very cold. That's the only reason I replaced it - it seemed to be fine otherwise.

As a fellow ping-victim, I'm sure you can imagine how stoked I was when the pinging stopped completely!

It hasn't pinged a bit since, and I smile every time I push that "87" button on a gas pump. My guess is either the signal rotor clearances or the signal coil resistances were out of spec and the ecu was getting faulty crankshaft position signals.

Because I was short on $$, I bought a new distributor from "Distributor King" on ebay - under $200 shipped. It isn't up to Denso quality, but it's not bad and it did come with a lifetime warranty. As far as performance goes, I couldn't be happier. I see that DK doesn't currently list a distributor for your year engine, but I'm pretty sure they used to, so you might ask them if they will have it in stock again.

This is the one I got for my 89:
http://cgi.ebay.com/ebaymotors/ws/eB...m=120395321901

I would be wary of a used distributor, since my engine was pinging as early as 110k miles, but if you found a real low-mile one, you might make out okay. New Densos are crazy expensive, over $400 at 1sttoyotaparts.

It has been 2 1/2 years now without a ping, and it's running better than ever - even starts a bit quicker. I hope you'll have the same luck with yours.

 

I'll check the signal rotor clearances and the coil resistances and see what they read. I think the factory service manual has the ohm specs in it.

 

http://personal.utulsa.edu/~nathan-b...12onvehicl.pdf

Page IG-23. I also read one case where someone found one of the terminals in the female side of the distributor connector was pushed back so it wasn't making contact - might be worth a look.

Good luck.

 

cool, thanks for the link,
it says to use a SST for the G1 and G2 gap on the distributor, or can I just use a feeler gauge to check for the 0.2mm-0.5mm range on both the G1, G2 and NE gaps?

 

I sure hope it isn't the head gasket... Don't have the time or money to deal with that right now

 

Ok, heres what I got:
Primary Coil Resistance (cold): about .5 ohm
Secondary Coil Resistance (cold): about 12k ohm

Distributor Air Gaps:
G1 & G2: 1.1mm
NE: .2mm

All signal generator resistances were in spec for cold

I'll do some driving today and check them hot. That G1 and G2 gap reading concerns me a bit - its about double what it should be, yet I didn't have the SST to measure it.

 

Does it ping on the highway? If not, then you have an air flow problem with the fan clutch hub failing at slow vehicle speeds. They tend to weaken with age and not move enough air for city driving. I replaced mine with a flex fan and the temperature gage quit spiking and it returned to normal temps just like when it was new.

My $0.02

 

Not to be confused with a Flex-a-lite fan.

 

yeah it pings on the highway. I don't have a problem with the temp gage spiking or overheating, so I figured the problem has to be in the ignition/fuel category. I borescoped the cylinders too and it does not appear that there is that much carbon on the piston/head.

 

SST is probably just a narrower and perhaps angled feeler gauge to make it easy to get a good reading on the G gaps. If you were able to fit your feeler gauge in there and measure the clearance, then the SST isn't necessary.

Sounds to me like you've probably found your problem. Timing is set by the computer, but it uses the crankshaft position signals from the distributor as reference. The flag to me was that it still pinged at 0 deg advance, which is exactly what mine was doing. And replacing my distributor immediately cured the problem.

When the gap is too great, the pulse generated is weaker, and we're talking about weak voltage to begin with. Add wire distance and slightly corroded connections, and there is probably too little voltage to make it back to the ecu.

I would try a known good distributor and see what happens.

 

I'll order one tomorrow and see what happens...

 

distributor didn't solve it. Did a lot of highway driving today and it was pinging. Pulled the plugs out and cleaned them. #4 and #6 were pretty oil fouled. I guess I should try cooler plugs, I've got stock plugs in it now - thought I put cooler plugs in it, guess not - and see what happens then.

 

I'm really sorry to hear that - I thought for sure that would do it - your motor's symptoms are just like mine was. Major drag - I know those things are expensive.

Just for curiosity's sake, which distributor did you use and was it new?

Since you've got oil leaking in your #4 & 6, have you run a compression test to make sure it's not rings? It's probably valve seals, but... would be good to be sure.

Have you checked your EGR as jhershner11 suggested? To check, let the motor warm up and hold rpms around 2500 while you (carefully) quickly touch the iron egr pipe where it goes into the plenum. Should be hot. You can also pull the vacuum tube off the egr valve when the motor is at 2500 rpm and test for vacuum in the tube with your finger. EGR reduces combustion temps, and that helps to reduce pinging, though I would think that bringing the spark advance back to zero would eliminate pinging even without the egr.

 

the egr is functioning properly - well at least when I take a vacuum pump and connect it to the egr and open the valve manually it works (engine stumbles and dies). I'll check it by touching the pipe to make sure it works on its own.

Oh, heres some pictures of the #4 & #6 plugs - I'm pretty sure its oil fouling:



I only drove a couple of miles today after cleaning the plugs, and I didn't hear any spark knock - but of course the engine didn't have time to warm up. I'll advance the timing back to stock again tomorrow, check the egr, do a compression test and see what happens.

Oh, the distributor was a by cardone. I've used their stuff before (cv axles, ps pump, brake calipers) and they seem to hold up pretty well. It does run MUCH better with the distributor and it starts better too. I guess the ecu doesn't have to 'guess' where the cam is now.

I really appreciate all of your input on this guys!!