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Car Forum / Toyota / Toyota Trucks / November 2006Ignition Timing misunderstanding
So I tried to answer this for myself, but I just don't get it: How the hell do you adjust the ignition timing exactly? I've got an '88 Toyota pickup 4x4 w/ manual transmission. I just replaced the head gasket, had a bit of trouble, but figured it out. Then it wouldn't start, so I adjusted the distributor like it says in the Toyota manual I spent a lot of dough on. The problem is that I really don't know what I am doing, so I don't understand what it means. Here's what I am thinking, feel free to call me an idiot. The book says to check the ignition timing, for a 22RE like mine, it says 5 degrees BTDC @ idle. Then further down, it says 10 -14 degrees BTDC. Is the engine suppost to stop at 10-14 degrees for it to start properly? And just what marks am I looking to line up when I turn the distributor to adjust the timing? Am I suppost to do that while the engine is running? And what if my idle doesn't settle properly after letting off of the accelorator? I have to punch it for it to settle down to the proper idle. It's not the cable, and I sprayed everything down around the springs to make sure it nothing was sticking there. Is there something inside of the throttle body that might be sticking, or some kind of vacuum problem? If we come to the conclusion that is is a vacuum problem, I'm going to take it to someone else to deal with, I had a hell of a time getting all of those tubes back in the right spots, and I still don't know what they do. Thanks. > So I tried to answer this for myself, but I just don't get it: > [quoted text clipped - 14 lines] > to adjust the timing? Am I suppost to do that while the engine is > running? > Thanks. First you need to buy a timing light. A timing light is a light gun, that uses a clamp probe on the 1st cylinder ignition wire to trigger a flash of light. The light will flash every time the 1st cylinder spark plug fires. With the engine running you point the timing light at the main pulley (harmonic balancer). Above the pulley, and attached to the oil pump is a little shelf with hash marks on it. A few of these marks are numbered, 0, 5, 8. These are degrees of advance. So the engine is idling and the timing light is attached to the battery for power and the 1st cylinder spark plug wire for a signal. If you point the timing light at the main pulley you will see the notch in the pulley lining up with the hash marks on the shelf. If you loosen the bolt that holds the distributor, and rotate the distributor, you will see the notch on the pulley move in relation to the hash marks. You will also notice the engine noises change. A carbureted 22R is set to 0 TDC, so with the engine at idle the timing light should show the notch lining up with 0 on the shelf. A fuel injected 22RE is set to 5 deg advanced, so you want to adjust the distributor until the notch lines up with the 5 on the shelf. NOTE: You must disable the vacuum advance before setting the timing, On a carbureted 22R you simply unplug the vacuum hose going to the distributor's vacuum advance unit (the little piston looking thing attached to the distributor). On a fuel injected 22RE you will see a electrical plug that appears to dead end in a little boot attached to the driver side engine compartment wall, just next to the air filter housing. There are 2 connectors held in little boots this way. The one you want only has 2 wires. take a small piece of copper wire and short across these 2 contacts by pushing the ends of the wire into the connector. You should hear the engine noise change. With the vacuum advance disabled you can accurately set the timing. Remember to re-enable the vacuum advance and tighten down the distributor bolt when done. > And what if my idle doesn't settle properly after letting off of the > accelorator? I have to punch it for it to settle down to the proper [quoted text clipped - 5 lines] > hell of a time getting all of those tubes back in the right spots, and > I still don't know what they do. On 22RE's the throttle body sensor sticks a little when cold and tends to rev the engine a bit higher. >> So I tried to answer this for myself, but I just don't get it: >> [quoted text clipped - 24 lines] > With the engine running you point the timing light at the main pulley > (harmonic balancer). And, HEREIN lies the trouble. He just did head work, and installed the cam(s) incorrectly. The motor is out of time mechanicly, and does not run. He either has the cams set wrong, or the distributor set wrong, or a combination of both set wrong. > Above the pulley, and attached to the oil pump is a little shelf with > hash marks on it. [quoted text clipped - 47 lines] > On 22RE's the throttle body sensor sticks a little when cold and tends > to rev the engine a bit higher. Ok, now the misunderstanding is my fault. My truck runs. It runs pretty well. But I kept reading about pinging and lagging, and I wondered if maybe my truck should run better than it does. A little more history. When I bought the truck, the engine that the previous owner had installed had about 12,000 miles on it. It ran really well. About a year and half ago, I was going through a lot in my life, noticed the radiator leaking and did nothing about it. So it ran hot one day, and blew the head gasket. At least that's what I thought, but I didn't know for sure until I got it apart. Had to do it myself because I couldn't find anyone to do it around here that I trusted for less than $1,000, this Monterey, CA, pretty expensive place for EVERYTHING. So I bought the Toyota manual, studied what I thought was relevant, and went to work. When I got it apart, I was glad that I was right, the gasket blew between the 3rd and 4th cylinders, no water in the oil. Seemed pretty straight forward at that point. No warpage, everything seemed OK to put it back together. I didn't take the cams, rockers, valves or any of that stuff apart because I didn't think it was necessary, Since I bought the truck, I only put about 25,000 on top of the 12,000 it had on the new engine. Everything looked clean, aside from a little carbon that I got off of the cylinder heads and whatnot. Nothing alarming. The timing chain never came off. I lined it back up properly with the cam sprocket, and put everything back where I thought it was supposed to go. But it wouldn't start, and then I realized that I just threw the distributor back on without even getting close to proper mounting. I fixed that, mostly, which is where I am now. My truck starts fine, it runs pretty good. But I think it should run a little better. THe throttle thing is not just when it is cold, it does it all of the time, which is why I thought that something was sticking. It's not the cable, it's something after that. I can't find anything in the book about throttle position sensor, though I have read about it a couple times here. Now as far as setting the timing goes, it wasn't clear to me that I was turning the distributor while the engine was running, now I got that. But, just to be clear, what does degrees of advance mean and why is it different on the different engines? I want to fix my truck, mostly because I can't afford for someone else to do it, but I want to understand what I am fixing, and some of the terminology doesn't lend itself to easy interpretation. Also, if the sound of the engine changes when you adjust the distributor, why do you need the light? Is it not possilbe to hear the correct timing, or just not a good idea for some reason that I wouldn't think of? I can't imagine that they are cheap, and I don't know if I can rent one from one of the parts stores. And I need to start driving this thing to work this week. How much damage am I doing? And what is the 10-14 degrees BTDC about? > Ok, now the misunderstanding is my fault. My truck runs. It runs > pretty well. But I kept reading about pinging and lagging, and I [quoted text clipped - 15 lines] > this thing to work this week. How much damage am I doing? And what is > the 10-14 degrees BTDC about? Timing is when the spark plug fires. Usually you need it to fire just before the piston gets to the top when starting. This gives time for the gas to burn and produce the gasses (power) while the piston is just starting to go down. As the motor speeds up, the timing has to advance (plug fires sooner) so the gas will start to burn sooner as the the piston gets over the top faster. The BTDC is before top dead center, when the piston is at the top. Firing too soon and you get the pinging and the piston is being pushed the wrong way. Too late and you do not develop the rated power. If you insist on trying to set the timing by ear and not with a light, then you may try this. Advance the timing some and drive off. If you do not hear the engine pinging (where the gas explodes instead of burning) advance the timing a small amount and try again. This is usually most noticable at slow speeds in the higher gears. When you hear the pining, back off a little. You do not want to hear the pinging as this is bad for the engine. > Ok, now the misunderstanding is my fault. My truck runs. It runs > pretty well. But I kept reading about pinging and lagging, and I [quoted text clipped - 49 lines] > this thing to work this week. How much damage am I doing? And what is > the 10-14 degrees BTDC about? 5 degrees advance is a stock setting. Adjusting a little on either side can make your specific engine run smoother. Start with 5 degrees and try driving it, then try 4 degrees, then 6 degrees, and see which one runs soother. Ok man I just did this same project about 6 months ago on my 87 yota 4x4 22RE and let me tell you it was easy pulling it apart but a pain to put everything back together perfectly. Anyways I had the same timing issue you are having my truck would backfire through the air cleaner box (where the filter is) I pulled the distributor out and cranked the motor manually to TDC and the put the distibutor back in at number 1. The truck started and then adjust your timing accordingly. > > Ok, now the misunderstanding is my fault. My truck runs. It runs > > pretty well. But I kept reading about pinging and lagging, and I [quoted text clipped - 56 lines] > Start with 5 degrees and try driving it, then try 4 degrees, then 6 > degrees, and see which one runs soother. You have a couple of major timing issues to sort through before you get to the fine tuning of TDC (top dead center) specifications. 1.) the valves have to be timed correctly to the pistons. This is done by setting the crank so the #1 piston is at the top of its stroke and setting the valves so the #1 set is closed. In this condition, there is a mark on the crank sprocket and the valve sprocket that should align to an imaginary line that also passes through the center of the shafts that the sprockets are mouted to. If the mechanical alignment of the valves and pistions is not correct, the engine will not run -- well, it _might_ run, but if it does, it is purley by chance and NOT by design. The timing here is established by the proper position of the timing chain. 2.) the ignition must be set to provide the spark at the correct time. This is done by installing the distributor with the rotor facing to the #1 position. In a perfect world, the distributor will be in the center of its adjustable range and be perfectly positioned, requiring no further adjustment. The world is not a perfect place though, and this is where you get to do the fine tuning by finding the precise TDC setting. The timing here is established by the properj position of the distributor. The distributor is driven by a gear on the cam shaft, which is driven by the timing chain. You can set the mechanical position of the cam(s) -- valve timing -- and not set the ignitiion timing, and the motor will not run. OR, you can set the ignition timing but fail to set valve timing, and the engine will not run. You have to set BOTH the valve timing and the ignition timing in order for the motor to run properly. It sounds to me as though you failed to properly establish the mechanical aspects of setting the timing -- you have some combination of problem with the timing chain and distributor. VARIATION Some motors do not have a Timing Chain, and cam position is set by the direct engagement of the gear on the cam shaft with a gear on the crank shaft, and other engines use a rubber belt instead of a chain. In any case, the principle that the cam and the crank have to be in time with one another remains the same. After the crank and cam are properly aligned, then one must properly align the cam and the distributor. No matter how the cam is driven, the cam must first be aligned to the crank, THEN the distributor is aligned to the cam. > So I tried to answer this for myself, but I just don't get it: > [quoted text clipped - 26 lines] > > Thanks. |
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