1997 saturn sl 160k misfire cyl4 sohc
#21
12-13-2012, 08:52 AM
The problem with a statement like this is believing is not verifying.
Your original symptom description seemed to indicate that once the engine was started it ran fine until you accelerated through the gears up through 3rd to about 3 or 4 thousand rpm and it would quit on the #4 cylinder. And would not start firing until such time you turned the engine off and re-started it.
And if nothing positive showed up I would try to verify one way or another the existence of a spark when in the failure mode.
None of which explains the lean appearance of the plug.
Your original symptom description seemed to indicate that once the engine was started it ran fine until you accelerated through the gears up through 3rd to about 3 or 4 thousand rpm and it would quit on the #4 cylinder. And would not start firing until such time you turned the engine off and re-started it.
And if nothing positive showed up I would try to verify one way or another the existence of a spark when in the failure mode.
None of which explains the lean appearance of the plug.
i shortened your post a bit, I believe it is getting spark because it is not misfiring all the time, if it wasnt getting spark, it wouldnt be an intermitten problem. Also, I didn't have to shut off the engine to get it to go back to normal, I just had to come to a stop and have the rpms drop to idle, misfire would go away and I would be good to go through the first 3 or 4 gears.
for example, I go from a traffic light up to 60 mph shifting at 3000 to 3500 rpms with 1/2 throttle, no misfire till the end of 3 gear or 4th and then it would constantly misfire in every gear no matter the speed till i come to a stop and let the rpms go to idle.
vice verse, if I drive away and only go to 30to40mph driving the same way, it sometimes doesnt misfire at all and will drive normal for a few miles. It seems to be dependant on engine load. cylinder 4s compression is 170 with is within 10% of every other cylinder. could something be jammed in the fuel rail? I'm thinking maybe its something valvetrain related? I'm gonna go clean all of the injector connectors soon.
#22
12-13-2012, 11:14 AM
When you automatically rule out things, then the chances of finding the source of the problem are greatly reduced. It can be an ignition problem just as much as it could be the injector problem, and it could even be compression.
It is remotely possible that one of the lifters is getting stuck. The bad thing about that is that in this failure mode, they don't make any noise. This is really remote and rare, but who knows. If that is happening, you should be able to see excessive wear on the affected cam lobe.
I haven't seen this in a long time, it used to plague engines back in the 60's and before, but the valve stems would get gunked up and the valve would stick partly open on occasions, but modern engines don't usually do this anymore.
It is remotely possible that one of the lifters is getting stuck. The bad thing about that is that in this failure mode, they don't make any noise. This is really remote and rare, but who knows. If that is happening, you should be able to see excessive wear on the affected cam lobe.
I haven't seen this in a long time, it used to plague engines back in the 60's and before, but the valve stems would get gunked up and the valve would stick partly open on occasions, but modern engines don't usually do this anymore.
Last edited by keith; 12-13-2012 at 11:18 AM. Reason: add stuff
#23
12-13-2012, 12:33 PM
When you automatically rule out things, then the chances of finding the source of the problem are greatly reduced. It can be an ignition problem just as much as it could be the injector problem, and it could even be compression.
It is remotely possible that one of the lifters is getting stuck. The bad thing about that is that in this failure mode, they don't make any noise. This is really remote and rare, but who knows. If that is happening, you should be able to see excessive wear on the affected cam lobe.
I haven't seen this in a long time, it used to plague engines back in the 60's and before, but the valve stems would get gunked up and the valve would stick partly open on occasions, but modern engines don't usually do this anymore.
It is remotely possible that one of the lifters is getting stuck. The bad thing about that is that in this failure mode, they don't make any noise. This is really remote and rare, but who knows. If that is happening, you should be able to see excessive wear on the affected cam lobe.
I haven't seen this in a long time, it used to plague engines back in the 60's and before, but the valve stems would get gunked up and the valve would stick partly open on occasions, but modern engines don't usually do this anymore.
also, the wires have been changed to brand new ones when i did the plugs. I pulled the spark plug today and the plug is black with a coats of carbon on it now. Only thing I changed was doing the injector o rings. I replaced the plug with a new one to see what it looks like after some miles. I'm thinking something is happening with the valvetrain that doesnt show up with a compression check. Maybe I will pull the valve cover soon to check. I checked the injector electrical connectors and cleaning them, but they had virtually no dirt on them anyway. Wires all look good and intact going to them.
#24
12-13-2012, 01:57 PM
I am not familiar with a noid light, never really needing one but this set of instructions:
http://www.noidlight.com/using-a-noi...tep-procedure/
seems to indicate that using one and changing RPM does not really tell you very much. Or am I reading it wrong?
http://www.noidlight.com/using-a-noi...tep-procedure/
seems to indicate that using one and changing RPM does not really tell you very much. Or am I reading it wrong?
#25
12-13-2012, 02:07 PM
Quote:
if I drive away and only go to 30to40mph driving the same way, it sometimes doesnt misfire at all and will drive normal for a few miles. It seems to be dependant on engine load. cylinder 4s compression is 170 with is within 10% of every other cylinder. could something be jammed in the fuel rail? I'm thinking maybe its something valvetrain related? I'm gonna go clean all of the injector connectors soon. Quote:
O.K., To me and reading what has been written and the work done this rings a bell. I just went through this last week end on another car that was experiencing an electric fuel pump failure.
Now while it was a fuel pump failure thus affecting all cylinders (an I-6) it was indeed performing exactly as this description and proceeded to get progressively worse as the fuel pump proceeded into it's failure mode.
This then explains the lean condition of that particular cylinder as read from the spark plug.
It is possible then that the suggestion of using a Noid tool may give additional information but it also seems to me that some very close inspection of the wiring going to the number four fuel injector might very well be in order.
Your process of elimination is beginning to pay off. Look at all the things and find out what ain't broken and then look some place else works pretty well too.
I am going to assume that it is not valve train related at this point in time.
A stuck lifter on an overhead cam engine makes noise just like they all do and a stuck valve hanging open will kill compression and depending on the engine pound holes in tops of pistons.
It does not sound as if it is valve train related to me.
But sometimes even that can not be confirmed for sure with out a tear down.
if I drive away and only go to 30to40mph driving the same way, it sometimes doesnt misfire at all and will drive normal for a few miles. It seems to be dependant on engine load. cylinder 4s compression is 170 with is within 10% of every other cylinder. could something be jammed in the fuel rail? I'm thinking maybe its something valvetrain related? I'm gonna go clean all of the injector connectors soon. Quote:
O.K., To me and reading what has been written and the work done this rings a bell. I just went through this last week end on another car that was experiencing an electric fuel pump failure.
Now while it was a fuel pump failure thus affecting all cylinders (an I-6) it was indeed performing exactly as this description and proceeded to get progressively worse as the fuel pump proceeded into it's failure mode.
This then explains the lean condition of that particular cylinder as read from the spark plug.
It is possible then that the suggestion of using a Noid tool may give additional information but it also seems to me that some very close inspection of the wiring going to the number four fuel injector might very well be in order.
Your process of elimination is beginning to pay off. Look at all the things and find out what ain't broken and then look some place else works pretty well too.
I am going to assume that it is not valve train related at this point in time.
A stuck lifter on an overhead cam engine makes noise just like they all do and a stuck valve hanging open will kill compression and depending on the engine pound holes in tops of pistons.
It does not sound as if it is valve train related to me.
But sometimes even that can not be confirmed for sure with out a tear down.
Last edited by uncljohn; 12-13-2012 at 02:10 PM.
#27
12-15-2012, 08:08 AM
Sorry Keith, I have worked on too many engines with some variety or another of either problem to agree with you as a universal definition. Especially when universally? Most people mix them up anyway until something is torn down to identify the problems. What needs to be done is identify what is going on and attempt to plan a direction to locate and solve the problem and that is complicated by both being cost effective and with in a working budget of the person trying to solve it. Blanket statements just do not work. Especially when they are miss-leading.
#28
12-15-2012, 03:00 PM
Maybe the term stuck lifter is not the best term to use as a collapsed lifter is also a stuck lifter. I am thinking of a lifter stuck in its expanded mode, one that is not compressing as it should. It will act like a solid lifter that has no valve lash and it won't make noise.
The more I think about it though, a stuck valve would make more sense but I really haven't seen the build up on the valve stems since leaded gas was banned. Carbon on the valve stems dates back to the leaded gas days, not sure why, but back then it was a big problem.
Its kind of interesting that some car manufacturers that use solid lifters actually recommend checking the valve lash only if there is noise coming from the valve train, but as valve seats erode over time, the valve lash closes up, and when it gets to zero, the valve burns shortly after. The owner who goes by the book never sees (or hears) that one coming.
The more I think about it though, a stuck valve would make more sense but I really haven't seen the build up on the valve stems since leaded gas was banned. Carbon on the valve stems dates back to the leaded gas days, not sure why, but back then it was a big problem.
Its kind of interesting that some car manufacturers that use solid lifters actually recommend checking the valve lash only if there is noise coming from the valve train, but as valve seats erode over time, the valve lash closes up, and when it gets to zero, the valve burns shortly after. The owner who goes by the book never sees (or hears) that one coming.
#29
12-16-2012, 06:49 AM
The last and most current motor in a car I owned with solid lifters was a 16 valve overhead cam Mitsubishi that when I sold it, the thing was 260,000 miles overdue for it's first and factory recommended 10,000 mile valve adjustment.
Personally I would set valve lash about 1 or 2 thousands over the recommend valve lash adjustment spec. and then pretty much not worry about what ever happens on something with solid lifters. Unless of course the slight klicking noise disappeared. Anything built to pass smog was also a bear to get after anything that took place in the head or heads. And also anything I build when said and done will also pass whatever the smog requirements are that cover the year car it is in which includes the Mercury Marine engine project I am building and is installed in my '76 Hornet Sportabout.
https://www.facebook.com/media/set/?...1&l=827fe42953
Having lived through leaded gas era, I never had a problem with stuck valves, or pretty much had a problem until current times. What ever the formulation of todays gasoline, if it sits in a car for a length of time where there is a fair amount of evaporation and that can happen in one stashed or stored and rarely driven there is some form of a deposit that will form internally to the gas tank that when dissolved by refilling the tank it is a bit like putting sugar in your gasoline and the valve will stick solid and a push rod will bend. That happens and it requires that the deposit be dissolved so the valve is free to move, the push rod replaced and the gas tank removed and cleaned out to remove the deposit.
I can imagine on an overhead cam engine this can get more than a bit expensive depending on what is ground away if and when a valve sticks. If a hydraulic lifter collapses due to age and miles and to some extent sitting for a long period of time and engine flush to eliminate gunk and a fresh oil change has a tendency to eliminate the problem. Te question becomes for how long and the answer is basically for how long do you need it to run and will it. And that depends to some on whether they are getting rid of it soon and only needing it to run that long or not. Switching to a heavier weight oil in the process helps in sure that it will also run and longer. High mileage cars need heavier weight oil and probably would have been in better shape if heavier weight oil has been used from the get go.
Personally I would set valve lash about 1 or 2 thousands over the recommend valve lash adjustment spec. and then pretty much not worry about what ever happens on something with solid lifters. Unless of course the slight klicking noise disappeared. Anything built to pass smog was also a bear to get after anything that took place in the head or heads. And also anything I build when said and done will also pass whatever the smog requirements are that cover the year car it is in which includes the Mercury Marine engine project I am building and is installed in my '76 Hornet Sportabout.
https://www.facebook.com/media/set/?...1&l=827fe42953
Having lived through leaded gas era, I never had a problem with stuck valves, or pretty much had a problem until current times. What ever the formulation of todays gasoline, if it sits in a car for a length of time where there is a fair amount of evaporation and that can happen in one stashed or stored and rarely driven there is some form of a deposit that will form internally to the gas tank that when dissolved by refilling the tank it is a bit like putting sugar in your gasoline and the valve will stick solid and a push rod will bend. That happens and it requires that the deposit be dissolved so the valve is free to move, the push rod replaced and the gas tank removed and cleaned out to remove the deposit.
I can imagine on an overhead cam engine this can get more than a bit expensive depending on what is ground away if and when a valve sticks. If a hydraulic lifter collapses due to age and miles and to some extent sitting for a long period of time and engine flush to eliminate gunk and a fresh oil change has a tendency to eliminate the problem. Te question becomes for how long and the answer is basically for how long do you need it to run and will it. And that depends to some on whether they are getting rid of it soon and only needing it to run that long or not. Switching to a heavier weight oil in the process helps in sure that it will also run and longer. High mileage cars need heavier weight oil and probably would have been in better shape if heavier weight oil has been used from the get go.
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