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Discussion Starter · #1 ·
My 97 850GLT (164K) began running roughly during a recent trip. Onset was intermittent at first--under acceleration loads only with check engine light illuminating and sometimes blinking. Soon it began to run poorly continuously. <p>Code reader shows that cyls 1-4 are misfiring. Removed cap and checked for cracks--found no visible discrepancies. Cap and wires are about 1 year old. Tried HEET in fuel with no improvement; replaced fuel filter with no improvement.<p>Can anyone suggest a logical diagnosis?<p>Thanks much.
 

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Re: Sudden onset: Missing on all cylinders; no codes other than misfiring (ThreeVolvos)

I don't have the magic diagnosis for you, just a few comments. First, I've learned over the years that the old adage is absolutely true - always make sure the ignition is right before you go suspecting all kinds of fuel problems. In your case I think that applies especially since the computer is telling you that it has ignition problems.<p>Second, with 164k miles, I'd certainly not be surprised if you have a bad ignition coil. My experience is that bad coils can cause a range of ignition symptoms.<p>Third, I think you might have been on the right track with the distributor, but consider the primary side since you are getting many cylinders misfiring. The distributor gets its timing signals from the cam position sensor, and advance/retard modified by the knock sensor. If one of these is bad (especially cam position), you could have all kinds of misfiring isues. What I'm not sure of, is whether the computer should be able to diagnose that problem for you - maybe so.<p>Fourth, another question is whether you or someone else added oil sometime before the problem occurred - when oil is spilled around the filler hole, it runs under the ignition wire cover and can pool down around the plug connectors. The OEM wires have those silicone collars that are designed to seal the tops of the spark plug wells, but if you have a <U>lot</U> of oil there, it can run past the seals. When I bought my first used 850, the owner told me that he had just changed the oil before turning it over to me - then the car started running badly within a day or two, and I found a good half cup of oil down in those wells (it had original plugs/wires with 100k on them).<p>Good luck with your troubleshooting.
 

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Re: Sudden onset: Missing on all cylinders; no codes other than misfiring (jhalbert)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>jhalbert</b> »</i></TD></TR><TR><TD CLASS="quote">Third, I think you might have been on the right track with the distributor, but consider the primary side since you are getting many cylinders misfiring. <b>The distributor gets its timing signals from the cam position sensor, and advance/retard modified by the knock sensor. If one of these is bad (especially cam position), you could have all kinds of misfiring isues.</b> What I'm not sure of, is whether the computer should be able to diagnose that problem for you - maybe so.</TD></TR></TABLE><br>Sounds like you have very similar problems to what I had in my 850. Went from bucking on the highway to doing it all around town. It came and went a lot. Mine ended up being the cam position sensor. Try that! <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0"> <p>FYI, I found very low compression in one cylinder and sub-par in 3 others (which I fixed with Seafoam <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0">), had just replaced the distributor cap, rotor, and plugs (and wires ~40k miles ago and checked them with a multimeter), discovered that the plug for the mass airflow sensor had corroded and was able to kill the car by wrenching on it, and even tried replacing the ignition coil. None of that fixed it until the cam position sensor was replaced. So, check all of those things, and then replace the CPS <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">
 

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Discussion Starter · #4 ·
Re: Sudden onset: Missing on all cylinders; no codes other than misfiring (StarmanDXE)

Thanks much, I've pulled the plugs; they all show carbon, and the gaps are way too big. Will replace distributor cap and plugs. If that doesn't work, I'll likely move on to the CPS. I'll post results.
 

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Re: Sudden onset: Missing on all cylinders; no codes other than misfiring (ThreeVolvos)

This is becoming more interesting. After replacing the camshaft positioning sensor, I'm down to misfiring on only two cylinders. While the roughness previously existed throughout the rpm range, now it is pronounced only at idle. Exhaust stink is also much better. Still, car is undriveable.<br>Codes now show only 1 & 4 misfiring. Checked connections for plug wires--all seems proper. I'm thinking that a new set of wires would be an appropriate next step, but would enjoy hearing thoughts.
 

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Make sure the wiring for the CPS is sufficiently far away from the plug wires. From what I recall, if they're too close, you can have interference which will mess with the CPS's reading.<p>I'm assuming, since you did the CPS, you did the distributor cap and the plugs? What about the rotor? What about a compression test?
 

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Re: (volvosince16)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>volvosince16</b> »</i></TD></TR><TR><TD CLASS="quote">Try cleaning your mass airflow with CRC mass airflow cleaner.</TD></TR></TABLE><br>Yes. Try cleaning the contacts for the plug for the MAF, too!
 

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Discussion Starter · #9 ·
Re: (StarmanDXE)

New plugs, rotor, and distributor cap installed this week--these made no perceptible difference except that I got a new code (see post made Mon 4/13). That's why, based on forum advice, I moved to the CPS which did seem to help. I had not thought at all about wire location, but now that you mention it, that would make sense, and I completely overlooked the possibility. I'll try that, as well as the MAF.<p>Thanks. Will "keep you posted" as to progress.<p>
 

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<IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0"><p>Good luck!
 

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Discussion Starter · #11 ·
Re: (StarmanDXE)

CPS, plugs, cap and rotor all replaced. Repositioned CPS wire to be as distant as possible from plug wires. MAF cleaned using CRC cleaner.<p>Rough idle continues. Pulled plugs 1 and 4--both still wet/carbony. Checked to see that the plugs were firing by pulling them, reattaching wires, and observing spark on top of engine. Plugs are firing.<p>Now I'm perplexed. Could this be a fuel injector issue? Did I inadvertently install a new problem? Would I still be well advised to install new wires? <p>Bill
 
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