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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / August 2005effects of late timing ?
Hi, I've been told that running an engine with timing too much advanced causes damage. But what's the story with late timing ? I found very little on usenet about late timing, except for power loss, "like an old man's car ..." My dealer adjusted the distributor because of pinging, about 5 degrees. But also, it had been pinging even when an anti-knock sensor was correcting. So ignition would have been late already. Would it just diminish loads on the piston and bearings ? Or can the pressure load the piston in another bad way ? And what is the effect of the camshaft sensor being moved ? It replaces the crankshaft sensor, and I was told by another dealer that turning the distributor does not affect timing. Yet, as I imagine, both timing and injection points are changed. Would this add to already abnormal loads ? Looking forward to your valuable opinions, MTIA Carl Theres no reason to monkey with retarding the timing. It will run sluggish & I can't think of any reason why anyone would want such a situation. Put base timing where it belongs, usually a degree or 3 more advanced won't hurt. If it still pings, scan it for any other possible problems in the EST ckt. or ( if you can afford it ) go up a grade in fuel. Good luck. Hi Pater , Maybe the dealer found timing was too advanced and sold it as having to retard a little ... I am taking that possibility serious ... There are no errors at readout, but I worry about the fuel lines being clogged. I emptied a tank one day, without running out of gas, on a relatively new tank. An engine rebuilder suggested he'd connect a data logger to the oxygen sensor and see if combustion is ok. But pinging is not included in the ECU error codes. EGR malfunction is. Thanks again, Carl > Theres no reason to monkey with retarding the timing. It will run > sluggish & I can't think of any reason why anyone would want such a > situation. Put base timing where it belongs, usually a degree or 3 more > advanced won't hurt. If it still pings, scan it for any other possible > problems in the EST ckt. or ( if you can afford it ) go up a grade in > fuel. Good luck. Engine will be sluggish, and tend towards overheating, and burning valves. So, yes, less mechanical stress, but more heat stress. > Hi, > [quoted text clipped - 19 lines] > > Carl > Hi, > > I've been told that running an engine with timing too much advanced causes > damage. But what's the story with late timing ? If the timing is too late you can get excessively high exhaust temperatures, increased possibility of burned exhaust valves, catalytic convertor damage. Basically you're opening the exhaust valve before combutsion is sufficiently complete so that you get more continued burning in the exhaust system and more incomplete combustion products dumped into the catcon. Five degrees of static timing (i.e., before the engine computer and any vacuum advance mechanism you might have perform make further adjustments) could be quite a bit, depending on where you were to begin with. I'd be more interested in figuring out why the engine is pinging, despite the presence of a knock sensor. First, has this been going on for a long time or did it start suddenly? Does it persist through changes in brand of gas? Are you using gas of inadequate octane raing? Are the conditions extreme (one or probably more of great heat, steep hills, heavy loads, hard acceleration)? These could exceed the dynamic range of the engine computer's ability to adjust things, or of the knock sensor's abilito to provide input. Is the engine old enough to be heavily carboned up inside? > And what is the effect of the camshaft sensor being moved? The same as moving a crankshaft sensor -- the crankshaft and camshaft have a fixed relationship determined by the timing belt or chain that connects them together. > I was told by another dealer that turning the distributor does > not affect timing That one makes me go "hmmm..." Perhaps what he meant was that it isn't the official way to adjust timing on your engine. Or tha t the engine computer will use other inputs to compensate for it (to a point). It would also make me want to drag out the shop manual and go back to basics on the positioning and adjustment of distributor and sensors, before further troubleshooting. Best of luck, --Joe Through it all, what the hell car/truck/engine are we addressing here? > Hi, > [quoted text clipped - 23 lines] > > Carl Something else lit a bulb here. Do you have a cam/crank sensor??? Seems that everything involving these things is distributorless. Why would you need 'em if ya got a dist??? To reiterate from the post above me here, whatta ya drivin'. Hi, Thanks all for the flood of suggestions. This is the first time I see some reference to damage from late timing. I'll post some later, this evening, but need to clear some other things now. I got a second car to help me out. Thanks, Carl > Hi, > [quoted text clipped - 19 lines] > > Carl Hi all, I finally got to reply to all this. I answered your questions beneath. I would not like to offend the dealership, so I choose not to mention the make, but I worry about what they have (not) done. It is a low-volume, four-cylinder, petrol engine, with a simple multipoint injection system, no MAF I was told, no crankshaft sensor but a single camshaft sensor and a mechanical distributor wich has to be adjusted for fixed timing. I can't really understand this, but it is constructed this way. It has 16 valves, manually adjusted, aluminium head, SOHC. It is quite new, 60000 mi. and consumes about 1 l oil in 4-6000 mi. It appears to have no real carbon build-up. What the symptoms are : sluggish response to throttle at idle, and sometimes also on acceleration, even thought it did not do this at first with this late timing. I noticed also a resistance to driving fast on motorway, but did not want to test it. No really smooth turning, a bit noisy, also at idle. When cold, idling flutuates, and it has not done this two months ago. A sharp high pitch ticking metallic noise, notably when cold, but also when warm on acceleration, and also sharply when you revv up at idle, just when the rpm goes down again. When the car has been left for a while after warming up, the noise is much less or gone for a while. I wonder if this can not be caused by injectors, but how would they tick just after revving up at idle ? No problem about running hotter, but I think the cooling is very good, it has never risen in temperature. The mpg has risen strangely before the problem arised, but I'm not sure it is a ecu fault or real fuel economy. It is sometimes corresponding on the actual mpg at fill up, and sometimes not. The display has been beeping and showing incorrect time and date and returning to the "thruth" afterwards. But the car was not behaving strangely at those moments. I have not yet had the fuel system checked out. ---------------------------------------------------------------- Now for your questions : "pater" <weavcowinory@aol.com <mailto:weavcowinory@aol.com>> schreef in bericht <news:1123585961.385601.140000@g49g2000cwa.googlegroups.com>... > Theres no reason to monkey with retarding the timing. It will run > sluggish & I can't think of any reason why anyone would want such a > situation. Put base timing where it belongs, usually a degree or 3 more > advanced won't hurt. If it still pings, scan it for any other possible > problems in the EST ckt. or ( if you can afford it ) go up a grade in > fuel. Good luck. I normally couldn't afford even the car at this moment ... But I always filled up with high octane quality fuel. Pinging is not logged in the engine error register. And there were never errors. Except for a "crankshaft sensor" error after the distributor was turned. Which is strange given the statement that there is none and it does not move with the distributor. ---------------------------------------------------------------- "Steve" <no@spam.thanks <mailto:no@spam.thanks>> schreef in bericht <news:8cSdnYDnDOOLVmXfRVn-qw@texas.net>... > If the timing is too late you can get excessively high exhaust > temperatures, increased possibility of burned exhaust valves, catalytic > convertor damage. Basically you're opening the exhaust valve before > combutsion is sufficiently complete so that you get more continued > burning in the exhaust system and more incomplete combustion products > dumped into the catcon. Can this valve damage explain the ticking metallic noise ? How can you find damage to valves ? Only compression and leak-test ? Or can valve stems and guides be as well victims to excessive heat and cause noise ? If too much heat is built up, would it lead to piston wear and - slap ? Can this be verified ? I know compression will eventually go down if this is the cause. But I would not want to get there. I'm using a second car to avoid all that. I imagine an emissions tester can check the cat ? ---------------------------------------------------------------- "Ad absurdum per aspera" <jtchew@california.com <mailto:jtchew@california.com>> schreef in bericht <news:1123605516.886963.85330@z14g2000cwz.googlegroups.com>... > Five degrees of static timing (i.e., before the engine computer and any > vacuum advance mechanism you might have perform make further [quoted text clipped - 3 lines] > I'd be more interested in figuring out why the engine is pinging, > despite the presence of a knock sensor. There should be no significant carbon build-up, but EGR could be a problem, there has been a large amount of oil consumed once. The EGR valve should be being monitored for errors I was told. No readout found. And it is possible the mixture is sometimes too lean, although the ecu should be correcting for this. In any case, spark plugs look normal. The coolant was changed and maybe not properly vented. Would a too lean mixture at cold cause pinging? The coolant passes under the inlet manifold to underneath the throttle valve. There are air ducts around the throttle passing this coolant duct. > First, has this been going on for a long time or did it start suddenly? I don't really know, I think it started quietly and has risen in importance and sound volume. There was a problem with valve lash, and different adjustments, and I thought this was there three months ago. In answering the question above, the anti-knock sensor can be triggered because of valve lash being too wide, and cause persistent late timing. I would not know when this started. The rotor has burning marks on the late end of the contact with the electrodes. As if it can't go any later anymore. So maybe a long time already. The timing was changed 600 mi ago, but the late timing through anti-knock sensor could have been there been there at least 1000 mi or even 3000 mi. > Does it persist through changes in brand of gas? I changed to an unknown brand once recently and had some problems, but two years ago, it did not - seem to - pose a problem. > Are you using gas of inadequate octane raing? Are the conditions > extreme (one or probably more of great heat, steep hills, heavy loads, > hard acceleration)? These could exceed the dynamic range of the engine > computer's ability to adjust things, or of the knock sensor's abilito > to provide input. No, it is the normal driving pattern I followed when the car was new. > Is the engine old enough to be heavily carboned up inside? As above, I don't think so. I took out an amount of loose carbonised particles with a vacuum cleaner throught the spark plug hole, but a dealer looked inside and found nocarbon now. > > I was told by another dealer that turning the distributor does > > not affect timing > > That one makes me go "hmmm..." Perhaps what he meant was that it isn't > the official way to adjust timing on your engine. Or tha t the engine > computer will use other inputs to compensate for it (to a point). No, he said it had no influence.I see that the fixed timing is set with an ecu ground wire, and timing lamp, by turning the distributor. But how, in the absence of a fixed crankshaft sensor, and so told fixed camshaft sensor, the timing can be adjusted this way I don't see. It is a combination of sensors and distributor, but I thought the distributor is only to pass on the high voltage. The coil is inside. There is a pin sticking out in the cap about the height of the rotor, maybe this is the ignition timing sensor. But it reacts to the rotor and not really on crank- or camshaft. Even then, one dealer persisted turning the distributor doesn't affect ignition timing at all ... And others refused to check ignition, saying they only adjust it through the ecu. Which they should never do ... > It would also make me want to drag out the shop manual and go back to > basics on the positioning and adjustment of distributor and sensors, > before further troubleshooting. My thought but not accepted by the dealers. > Best of luck, > --Joe Thanks ---------------------------------------------------------------- "pater" <weavcowinory@aol.com <mailto:weavcowinory@aol.com>> schreef in bericht <news:1123634081.380530.83920@g47g2000cwa.googlegroups.com>... > Something else lit a bulb here. Do you have a cam/crank sensor??? Seems > that everything involving these things is distributorless. Why would > you need 'em if ya got a dist??? To reiterate from the post above me > here, whatta ya drivin'. As above, I dare not say and I don't know how it works. If I would have a shop manual ... ---------------------------------------------------------------- |
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