Since I replaced my head gasket two years ago and had the valves done, my 22REC has had some pinging (under load) issues which force me to run premium fuel all the time. Not too big a deal, so I put up with it.

Yesterday the engine developed a pretty good miss at idle and lost a fair amount of power (it drives, but it's intermittently slow up hills). Lately the idle has been eratic, sometimes it's a bit high and sometimes it's right where it should be. Here's what I've done so far to chase down the more serious miss/power problem:


- Changed wires, plugs, cap and rotor. All were almost two years old, plugs had very heavy white "snow" looking buildup, almost 1/8" thick in places. Apparently this is "ash" buildup from fuel additives (plenty of those in CA) or oil leaking past rings or valve seals. Guess I need to change 'em a little more often.

- Checked fuel pressure and pressure regulator, seems to be working fine. The pressure goes up 10psi when you remove the vacuum line from the regulator, and really spikes when you pinch the return hose closed. Oddly the extra 10psi doesn't seem to have much affect on idle RPM, and when you pinch the return line and really drive up fuel pressure the engine starts to stall.

- Checked EGR, Mity-Vac pump on the EGR valve kills the engine as it should.

- Checked TPS, all within spec.

- Checked timing, timing is 5* TDC with short-circuit, per spec.

(Next will be a compression check, didn't bother with it tonight)


Now the weird thing is what happens if you remove the timing jumper and watch the timing while you rev the engine. It hovers at the correct advance at idle, then just after you crack the throttle the advance jumps directly to 43* TDC (used a dial-back-to-zero timing light) and stays there. It doesn't matter how much you rev up the engine, doesn't matter how slowly you increase or decrease RPM, the advance is precisely 43*- 44* at any RPM that's above idle.

This can't be right, anyone know anything about Yota EFI timing advance?

Oh yeah, it's an '87 Runner with 230K miles.

Just drove it about 15 miles, power is a lot better with the tune-up parts but the miss is still there...if the compression check turns out okay I suppose it's time to look at injectors.

But that still doesn't explain this timing advance thing...

Im willing to bet that toys have a mechanical advance under the plate in the distributor. If the weights are sticking that could be the cause.
DWT

Hey Drew,

I've had my '85 22R disty apart several times. It gets pretty gummed up inside after high mileage. You might want to pull it out and clean it. There are two springs for the mechanical advance that work with the centrifigal weights. You might have a spring missing or broken, or the weights are sticking. There are some E-clips in there, be careful, they tend to disappear when removing or installing. You can buy the springs at Toy dealership, their about $2.50 each. A miss can be a "misstery". Other than having the injectors cleaned and tuned, you might try running a can of Berryman Chemtool B-12 in a full tank of fuel. Let us know what you find.
Gnarls.

I could be wrong, but I don't think the EFI distributors have anything under the rotor but a little magnetic "pickup" sensor.

Is it possible the timing throughout the RPM range looks strange because I'm revving it with no load?

Hey Drew,
Yep, I think you are right. I looked in my 1986 FSM and it doesn't show any mechanical advance, like the 22R. Sorry. It's got the ESA (Electronic Spark Advance). It's controlled by the ECU. Other than air gap inside the disty, it's all up to the ECU. There's an on-vehicle inspection test procedure listed in the FSM. It may be a sensor giving the wrong data to the ECU. I'm not and EFI expert, so I'll back out now. I don't think the load has anything to do with the total ignition advance, but with EFI, I'm not sure. Let us know what you find.
Gnarls.

Mine acts the same way although it seems to jump just another 10-15 deg.

I can also dial my timing light back to zero to see what the advance is so maybe I'll have time to check it in the next few days.

I just thought that was normal. :confused:

Unjumpered, it runs about 12~14 deg. adv. and the moment that I rev it, it jumps WAY advanced.

If this is not correct behavior, I'd love to know. :p

EDIT: This is also a 1987 22RE

My 85 EFI 4Runner had the same problem. It is due to a brain dead computer. The computer has a default mode that allows the engine to run, but low RPM performance is bad. The electronically controlled advance should slowly advance with RPM, and you will see this with a timing light as you increase throttle. I bought a replacment computer (used) and it solved my problem.

Originally posted by 76tlc
My 85 EFI 4Runner had the same problem. It is due to a brain dead computer. The computer has a default mode that allows the engine to run, but low RPM performance is bad. The electronically controlled advance should slowly advance with RPM, and you will see this with a timing light as you increase throttle. I bought a replacment computer (used) and it solved my problem.

Whoa! Maybe this is why I had so much trouble passing smog II?

I'm still able to pull codes from mine. I would think that means it's still working? This is very interesting. Anyone else?

My brother's '87 Runner pings really bad, even though his EGR (and everything else) seems fine. Wonder if it's a bad year.

- Checked EGR, Mity-Vac pump on the EGR valve kills the engine as it should.
plugs had very heavy white "snow" looking buildup, almost 1/8" thick in places.
(Next will be a compression check, didn't bother with it tonight)

I think you are on the right track but might be playing to much into the timing advancing off idle thing sounded fairly normal to me, and like most (good since making tests) like I'm sure you like I know there is no spec's.

Your EGR test is not complete until you tee into the vacuum line and vacuum is confirmed while on your pinging test drive.

One pinging symptom some over look is carbon build up raising your compression, holding the valves open slightly, and carbon soaking up the fuel causing an odd burn.

Valve adjustment is another, after you get it warm and check the compression, could have a burnt valve by now.
;)
Dan

editedMy 85 EFI 4Runner had the same problem. It is due to a brain dead computer. The computer has a default mode that allows the engine to run, but low RPM performance is bad. The electronically controlled advance should slowly advance with RPM, and you will see this with a timing light as you increase throttle. I bought a replacment computer (used) and it solved my problem.

Sorry dude but I'm having hard time swalowing that one, mostly because you cant say it was the "same problem" unless your timing was advancing the same way off idle and that is somthing on EFI rigs that like never gets checked, and if it cured your pinging problem well then for how long and did you do anything else at the same time?? When ever you disconect the battery the computer has more of a base setting untill it gets driven for awhile could it have been that it stoped pinging for like an hour or so? I guess what I want to know was this a (confirmed) one part fix, In other words can you plug that old computer back in it and it will ping?

You said you checked the timing with the pins conected while doing that test did the timing actualy drop down at idle or stay the same?

Dan

Originally posted by Wazzobie
You said you checked the timing with the pins conected while doing that test did the timing actualy drop down at idle or stay the same?

Dan

It dropped, which helped confirm that the TPS is properly adjusted.

.It dropped, which helped confirm that the TPS is properly adjusted.

Cool!! http://www.pirate4x4.com/ubb/icons/icon14.gif
Guess it comes to pulling them plugs again for that compression check should help show whats up with a more accurate plug check now that it has some miles on it.

I'm gonna go see what the timing does on my '86 right now...if it has a smoothly increasing advance with increasing RPM I'll try swapping computers and see what happens.

I'm gonna go see what the timing does on my '86 right now...if it has a smoothly increasing advance with increasing RPM I'll try swapping computers and see what happens.

http://www.pirate4x4.com/ubb/icons/icon14.gifCool Beans:D do you have that kinda timing light?

I have that craftsman dial one and wish they used a heat proof plug wire clamp that plastic crap is tough to keep together

Yup, it's a Craftsman dial-back-to-zero light.


Well, didn't really get a conclusive result:

The '86 (LC EFI cam, LC adjustable cam gear advanced 4* for more torque, Downey header, 2.5" exhaust) is at 10* TDC at idle and jumps to 30* when the TPS tells the computer it's not idling anymore. Once at 30* it climbs about 5 more degrees as you really rev it up.

The '87 (DOA cam, stock everything else) is at 10* TDC at idle and now jumps to 38* when you crack the throttle. (I pulled the EFI fuse to reset the computer earlier today, which may be why the off-idle advance isn't 43* like it was last night.) It also climbs several more degrees when you really wind it up.

I'm surprised there isn't more range of advancement, it seems like a really high RPM would need a lot more advance than a low RPM, five degrees or so change doesn't seem like much. I figure the modifications to the '86 are probably what makes the difference between jumping to 30* and jumping to 38*.

So I didn't bother swapping computers, for now anyway. Figure I'll try a few tanks of EFI cleaner, I always run cheap-ass ARCO gas...

Originally posted by 76tlc
My 85 EFI 4Runner had the same problem. It is due to a brain dead computer. The computer has a default mode that allows the engine to run, but low RPM performance is bad. The electronically controlled advance should slowly advance with RPM, and you will see this with a timing light as you increase throttle. I bought a replacment computer (used) and it solved my problem.

How much does your advance increase as you move toward redline? Maybe both of my computers are bad - LOL.

General rule of thumb (IME)is don’t go more then 46 total 36 if you want to be really safe.

A worn timing chain or lack of tensioned pressure might be causing the cam to move farther at different times.

Will it stop pinging when set at 0 TDC

I'm surprised there isn't more range of advancement, it seems like a really high RPM would need a lot more advance than a low RPM, five degrees or so change doesn't seem like much. I figure the modifications to the '86 are probably what makes the difference between jumping to 30* and jumping to 38*.

Sure if you run race fuel:D



Edited
Figure I'll try a few tanks of EFI cleaner, I always run cheap-ass ARCO gas...

That stuff is bad news man hard on your fuel pump, EFI injectors, and computer from the electrical in the injector breaking down to a short.

I highly recommend Motor Vac Injection, Plenum and, Decarbon there like $99 bucks service here at my shop 2000 Auto Repair Molalla OR Toyotas kinda suck to do, compared to most the domestic rigs. If you get that service some where make sure they are using Motor Vac solution not the SnapOn just that kills electrical to from what I hear.
Dan

Sure if you run race fuel

Before I get flamed on that there is a fine line in the higher #'s I dont know.




Edited'
Your EGR test is not complete

If that intake pasage is restricted the motor wont die when you mighty vac that EGR will it die? If at around 750-800RPM the engine should die

thats right you said it killerd the engine

- Checked EGR, Mity-Vac pump on the EGR valve kills the engine as it should.

Alldata says 10*to15*BTDC with no timing conector at idle is normal.