I was checking the ignition timing on my KA24DE with 250k miles ( all city) the other day, and noticed the ignition timing was not steady.What I was wondering is if this could be due to a stretched timing chain or a faulty tensioner? It has the infamous KA timing chain rattle at startup and has for some time, so I wonder if the cams and the "transfer sprocket" ( don't know technical name) are varying their timing at idle due to stretch. It also doesn't idle perfectly smoothly and all sensors are in perfect order, so maybe this is the reason why? Thanks for any opinions, I just want to be sure this thing is good to go in a few months when I drive from Florida to New York. Throwing a timing chain en route would suck!
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1998 Nissan Frontier XE/2wd/5spd 1 owner, 264k miles
1985 Olds Cutlass, 350 Chevy, owned for 14 years
WANTED: 1968-1973 Datsun 510 or 1991-1994 Sentra SE-R http://www.myspace.com/junkyardengineer
The only way your going to get a change through the timing chain is if it jumped a tooth. Which I doubt has happened in your case. If it jumps too many teeth, you'll bend your exhaust valves.
The only way your going to get a change through the timing chain is if it jumped a tooth.
Are you sure about that? I would think that as they chain stretches (which I know they did in the olden days) that the crank and cam(s) marks would not line up like they did before the chain streched and that would affect timing, no?
Quote:
Originally Posted by himilefrontier
...the ignition timing was not steady...
But, I would think a stretched chain might just change the timing, not cause it to vary.
Is the distributor bolted down tight? I would think that a worn distributor might cause varying timing too.
Just some thoughts.
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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd My Frontier Page
If your timing chain stretched to the point of timing marks not being aligned, you would have serious engine problems as I stated before. That is a fact. I also mentioned that the engine should be scanned and scoped on a different thread where he mentioned his problem about an intermittent miss on idle. Shooting in the dark is not the way to diagnose a problem.
If your timing chain stretched to the point of timing marks not being aligned, you would have serious engine problems as I stated before. That is a fact. I also mentioned that the engine should be scanned and scoped on a different thread where he mentioned his problem about an intermittent miss on idle. Shooting in the dark is not the way to diagnose a problem.
I remember the thread he's referring to, I also jumped in on that one. Occasional misses at idle are not an indication of timing problems. Such problems are actually fairly common, almost every vehicle on the road has occasional misses and stutters at idle. As NissanMadness says, if your timing chain was so stretched that it was throwing the timing off you'd notice a lot more than a miss at idle. The engine behavior would change in between throttle-on and engine braking situations becuz the cam pulley would rotate further than it should while the chain slack got taken up, and you'd have some major retard/advance surging issues going on every time you changed throttle input.
I'd agree with BTF/PTM that the timing is not a source of an occasional miss. A stretched timing chain would retard the timing to some extent but that would be a constant condition. I'd think that the timing should not be variable as the tensioner should keep the chain tension constant as the engine varies speed (of course, if the tensioner is also going away then the timing will vary).
Himilefrontier, I'd invest in a timing chain and tensioner if the engine is otherwise sound. While chains are not as fragile as belts they do fail. A chain failure may be catastrophic in the 4 cylinder engine.
Also, just to get this straight, IGNITION timing is not the same thing as CAMSHAFT timing. Himile, when you mention that you were checking your ignition timing, I'm assuming you did this with a timing light?
Not sure what type of ignition system the 4-banger uses, but i know the 05 and older V6 models have a distributor, so the 4-bangers probably do as well. You can adjust your ignition timing simply by rotating the distributor (as you probably already know). That will change how your engine idles. Also, misses at idle can be a result of certain types of gas (crappy gas like Arco will cause it to happen more), spark plugs not being perfectly gapped, engine valves not seating completely against the cylinder head (this is more common in high-miles engines becuz the valve guides are more worn), and lots of other things. Unless your engine is drastically loose at idle and sputters and shakes, don't worry about it. My brand new 2006 has an occasional rumble and stutter at idle, it's just how engines run.
As for that infamous chain rattle, it certainly won't hurt to replace the chain and tensioner if you've got that many miles.
Also, just to get this straight, IGNITION timing is not the same thing as CAMSHAFT timing. Himile, when you mention that you were checking your ignition timing, I'm assuming you did this with a timing light?
You are right that ignition and camshaft timing are not the same thing (the first is the relationship of the spark to the piston position and the second is the relationship of the valve open and closing operation to the piston position). But, since the distributor is usually run from the camshaft, both are affected by a worn timing chain.
By the way, my 2001 KA24DE engine does use a distributor.
Steve
Last edited by azrocketman : Dec 11th, 2006 at 01:35 PM.
You did mention that you have 245K miles on this truck with all city driving. Do you ever take it on the highway to blow out the carbon? You know with all the high mileage you have city driving, it would probably be damn near double if you converted it to highway mileage. There is no silver bullet. You can change the timing chain, which it does probably need, then suppose you have the same problem. When you go to a doctor, the first thing they do is take all your vital signs. Blood pressure, temperature,x rays etc... It gives them a starting point to help you out. Same thing with an engine scan and scoping of all sensors, injectors etc.... A compression test would also be included. It helps narrow down the problem and gives a mechanic a starting point in diagnosing the engine. You've already spent alot of money by changing different parts and having the same results. On some distributors, you have to disconnect the ecm wire, to set your initial timing. And when plugged back in will change the timing, because the ecm and sensors take over. I wish you well whichever way you choose to go.
I did perform a compression test, all 4 cylinders were at least 175psi. IIRC, one was even at 195 psi....WTF? ( That's what got me thinking about valve clearences and the odd possibility that the cams are not opening the valves long enough to bleed off excess cylinder pressure due to reduced overlap)I noticed the timing issue when using my Craftsman Dial back timing light, which I had out because I had just set the timing on my neighbor's 1973 Fiat 850. The truck does see some highway miles , depending on how much junkyarding I do in a given week. I put about 100-200 miles of junkyarding a week on it when I am building a project car ( I have a 360 V8 powered 1979 AMC Spirit and a 350 Chevy powered Olds Cutlass as well), or drive it a few hunderd miles when I'm bored. I have also taken it out and just run it a hundered miles or so in the country on the interstate to see if that was the issue, but it made no difference.I have noticed this unstable reading of the ignition timing before on other cars, but not on every car I test. Oh, and the distributor shaft is fine, no play in it. I have run Mobil 1 synthetic in this engine most of it's life, which is probably why it uses virtually no oil. I think the timing chain is a prudent thing for me to do soon as long as the engine passes an oil pressure test. If the bearings are going bad, there's really no point. Anyone know what thread the oil pressure fitting is so I can add a sender?
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1998 Nissan Frontier XE/2wd/5spd 1 owner, 264k miles
1985 Olds Cutlass, 350 Chevy, owned for 14 years
WANTED: 1968-1973 Datsun 510 or 1991-1994 Sentra SE-R http://www.myspace.com/junkyardengineer
Most oil pressure senders I've seen are 1/8-27 npt. But don't take my word for it. I've seen others that are 1/8-28 bsp. My best advice for you would be to remove the sending unit and put it up next to a thread pitch gauge. If you have a tap and die set, there should be one in the kit.
Most oil pressure senders I've seen are 1/8-27 npt. But don't take my word for it. I've seen others that are 1/8-28 bsp. My best advice for you would be to remove the sending unit and put it up next to a thread pitch gauge. If you have a tap and die set, there should be one in the kit.
I'll try it, but all of my taps and dies are SAE, not Metric, and I don't know if the gauge has national pipe thread as an option. I have never heard of BSP threads before, what does BSP stand for?
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1998 Nissan Frontier XE/2wd/5spd 1 owner, 264k miles
1985 Olds Cutlass, 350 Chevy, owned for 14 years
WANTED: 1968-1973 Datsun 510 or 1991-1994 Sentra SE-R http://www.myspace.com/junkyardengineer
I'll try it, but all of my taps and dies are SAE, not Metric, and I don't know if the gauge has national pipe thread as an option. I have never heard of BSP threads before, what does BSP stand for?
BSP stands for British Standard Pipe. Definetly check the thread pitch, just to be safe.
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