94 Buick LeSabre misfires, error 300

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Pull the egr and clean the carbon , may not be seating could cause a definite roughness at idle, worth a try, sometimes even that won't work and they need to be replaced. A scanner can pick up that roughness as a mis fire
because the pcm uses the crank sensor to see variations in crankshaft acceleration after each firing event, this can set a random misfire code.

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Alpha One wrote:

Sounds like the timing is off and the computers can't compensate. Not sensor-related, but mechanical.
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I STILL have the same problem with a 94 Pontiac SSEi, never resolved, the car is currently not being driven. Mine seems to miss more on #5 cylinder and on a few others as load is increased. It also only misses when under boost conditions. Sounds like you have done everything I had tried also. I don't remember checking the timing. If I did it wasn't off. I have tried to find a fuel pressure tester. Have been wondering if the pressure may be low.
Let me know if you get your problem resolved.
Thanks, Jeff

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I am not yet sure what it is, but yesterday I removed the EGR valve and looked at it. I didn't see carbon build up but I did push the valve a few times in and out. Afterwards the car was running smother. I have to see in a few day what happens. I thing the valve might have been getting stuck. Yesterday I got code 406, EGR spindle position error. I had this error a week or so ago, then it went away. Because it disappeared I didn't think much of it, but if it gets stuck in an open position the engine will run rough, or not at all if wide open. In this case, it would try to start and die immediately. If it's not this, then I would be inclined to thing it is the timing chain loose or worn out. Not good, but its not as difficult as it appears to change the timing chain.
In your case, if the car does worst when accelerating , it can be due to low fuel pressure. Low fuel pressure may be cause by a bad pump, a restricted filter or bad fuel pressure valve. But... other things can cause similar problems.

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Good work, maybe you are on to something, with the egr, I saw this on a 93 Bonney, same type issues but more erratic, anyway you can get a rough idea of the chain condition, get a socket and good size handle on the crank bolt and rotate the crank back and forth , should be a slight amount of free movenment before the cam can be felt moving, a little subjective here as to what is normal.

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"Alpha One" wrote: > My 94 Buick LeSabre misfires almost constantly on cylinder 6, > but it also > misfires a lot on 5 and some on 3. I get only error 300. > > I have the Actron ScanTool that tells me what the car is doing > and during > the same space in time 1,2,3 and 4 is firing while 6 is not. > Sometimes 5 and > 6 are not firing or, less often, 3 doesn't fire. > > Also, if I connect a timing light to each spark plug wire > while the engine > is running I see how often the strobe light doesn't flash. 6 > is the worst, > then 5, number 2 I thing does it less or almost never. > > The misfiring happens randomly. > > The Crankshaft sensor was replaced 30,000 or 40000 miles ago. > Do you think > it could be the Ignition Module? > > Antonio
ahh the chev v-6 misfire, with those kinds of numbers on compression (offset) i would be looking at the timing chain. injector control is driven through a camshaft sensor in the timing cover which is triggered by a magnet mounted in the timing chain upper cam gear. very common for this magnet to seperate and no longer properly trigger the cam sensor. i would rec. dealer parts on this setup as they have changed magnet design, tensioner design etc. good luck.
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I checked and the magnet is there.

http://www.autoforumz.com/GM-94-Buick-LeSabre-misfires-error-300-ftopict112936.html
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"Alpha One" wrote: > I checked and the magnet is there. >
> > > "Alpha One" wrote: > &nbsp;> > My 94 Buick LeSabre misfires almost constantly on > cylinder 6, > &nbsp;> > but it also > &nbsp;> > misfires a lot on 5 and some on 3. I get only error > 300. > &nbsp;> > > &nbsp;> > I have the Actron ScanTool that tells me what the > car is doing > &nbsp;> > and during > &nbsp;> > the same space in time 1,2,3 and 4 is firing while 6 > is not. > &nbsp;> > Sometimes 5 and > &nbsp;> > 6 are not firing or, less often, 3 doesn't fire. > &nbsp;> > > &nbsp;> > Also, if I connect a timing light to each spark plug > wire > &nbsp;> > while the engine > &nbsp;> > is running I see how often the strobe light doesn't > flash. 6 > &nbsp;> > is the worst, > &nbsp;> > then 5, number 2 I thing does it less or almost > never. > &nbsp;> > > &nbsp;> > The misfiring happens randomly. > &nbsp;> > > &nbsp;> > The Crankshaft sensor was replaced 30,000 or 40000 > miles ago. > &nbsp;> > Do you think > &nbsp;> > it could be the Ignition Module? > &nbsp;> > > &nbsp;> > Antonio > > > > ahh the chev v-6 misfire, with those kinds of numbers on > compression > > (offset) i would be looking at the timing chain. injector > control is > > driven through a camshaft sensor in the timing cover which > is > > triggered by a magnet mounted in the timing chain upper cam > gear. very > > common for this magnet to seperate and no longer properly > trigger the > > cam sensor. i would rec. dealer parts on this setup as they > have > > changed magnet design, tensioner design etc. good luck. > > > > -- > > Posted using the http://www.autoforumz.com interface, at author's request > > Articles individually checked for conformance to usenet > standards > > Topic URL: > > http://www.autoforumz.com/GM-94-Buick-LeSabre-misfires-error-300-ftopict112936.html > > Visit Topic URL to contact author (reg. req'd). Report > abuse: > > http://www.autoforumz.com/eform.php?pW0057 > > > >
is the magnet doing its job. check to see if there is any magnetic field remaining in it. definetly replace this magnet when you replace the timing chain.
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It did atracted a screwdriver when I tuched the magnet with it.
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Alpha One wrote:

When was the last time you replaced the wires, cap and rotor? If you did, did you use AC Delco parts?
Ken
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