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Misfire #1 Cylinder

27K views 112 replies 12 participants last post by  aquanaut20 
#1 ·
Stated this AM after sitting for a few days. Prior to that no problems (other than needed 3rd member rear end replacement) which I was geting ready to do. Engine has been running like a top. Today engine idled rough from the start and was obviously misfiring at all rpms. Flashing SES light confirmed this and also had a P0301 code (or 0401) whichever one indicates "Misfire #1 Cylinder". Only drove for a few miles but problem persisted. Plugs, plug wires, disty rotor, timing set, timing belt, pullys, all less than 10k old. Any ideas on where to start?
 
#3 ·
Rain? Any water in the spark plug holes?
 
#4 ·
I had the same problem not too long ago and all I could figure out was somehow, someway, water got into something. What fixed it for me was soaking everything electrical in WD40, down the spark plugs, on the wires, all over the coil packs and inbetween every connector I could get my hands on: fuel injectors, TPS, ISC, cam sensor, even the big ones on the firewall. After that it ran like a champ again
 
#5 ·
No water in plug recess and the plug looks brownish-red with no evidence of fouling. I haven't checked the spark yet but I will. "Noghri" may be on to something. In cleaning off some really persistent bird poop a few days ago I may have over-agressively sprayed water into those side vents towards the rear edge of the hood. Yesterday I noticed some large connectors next to the distributor that could have gotten pretty wet. I happen to have a new can of WD-40 and will try that also. Thanks.
 
#6 ·
Just completed transfering the original 3rd member into a newer (no rust) rear end housing. The nicer 3rd member howled like a banshee so I replaced it with the original 3rd member which is fine. All back together now and nice and quiet (as a tracker gets, I suppose) in the rear.
However after sitting for a few weeks during the rear end replacment my "#1 Cylinder Misfire" has now progressed to a "P0300-Multiple Random Misfires". I tried the WD-40 spray fix after my last post but no luck. It seems like it is running on 2 cylinders at most. Could it be that sensor that sits just below the lower timing belt pulley? It has been fairly dry and warm here so I was thinking that if it was moisture related it might have dried out. Apparently not. Any suggestions at this point?
 
#7 ·
However after sitting for a few weeks during the rear end replacment my "#1 Cylinder Misfire" has now progressed to a "P0300-Multiple Random Misfires". I tried the WD-40 spray fix after my last post but no luck. It seems like it is running on 2 cylinders at most. Could it be that sensor that sits just below the lower timing belt pulley? It has been fairly dry and warm here so I was thinking that if it was moisture related it might have dried out. Apparently not. Any suggestions at this point?
What exactly have you done so far? Check the distributor for cracks? Check inside for wear?

10k on the parts means nothing - have you checked them over?
 
#8 ·
Along the lines of what Gumby said:

If the distributor was slightly cracked, not seated exactly right or anything you could end up with condensation.
 
#9 ·
Random misfire is for conditions that affect at least 2 cylinders, so you need to check things that deal with more than one cylinder - like fuel pressure, condition of battery, vacuum leak, timing, etc.
You may want to give details about how the car is actually running.
 
#10 ·
Finally had some time to dive into it. The real culprit I belive is, per one of Bex's suggestions, the battery. It had a severly corroded positive terminal and was clearly leaking with battery fluid in the battery tray. After cleaning, the positive terminal clamp was about 30% eaten away. On the plus side - the distributor was clean and dry on the inside, no cracks and very mild deposits on the plug terminals which I cleaned off. The plugs all had black sooty deposits and smelled slightly of gasoline which I would think is normal for a plug that fires only occasionally. Plugs gaps were uniform and just slightly greater than .028 (normal wear and tear from last install 10k ago) and I adjusted them all to .028. I did find a wire on the distributor harness, black/red, where the insulation had been burned through due to another wire which was draped across this harness had shorted and burned through the protective casing of the entire distributor wiring harness bundle. A PO had run a wire from the positve terminal of the battery across the back of the engine bay and back to the left rear tail light to power a trailer wiring harness. It shorted a few months ago and fried itself melting this insulation on the distributor harness. It doesn't seem to have melted/damaged any of the wire in the black/red wire, just the insulation. All of the other wires are OK. My plan is to seal this wire with tape to protect it from moisture, put it all back together, add a new battery and see what happens. My guess is based on the evidence, Bex's guess of "bad battery" will be the answer. Fortunately, in digging around I found this bad wire in the distributor harness and fixed it. I'll let you know.
 
#13 ·
Installed new battery (bought today) and plug wires (I already had them). STILL random misfires! It seems like a steady and rythymic stutter (duh!, duh!, duh!, duh!, duh!) and seems like it's running on two cylinders. The exhaust smells of unburnt gas and the engine stutter remains as RsPM increase. I have not let it run but for a few seconds, so as not to trash the cat which is fairly new, but just to verify that it is not idling smoothly as before this all started. After removal, all plugs were virtually identical in their appearance and smell (very slightly of unburnt gas). No moisture in distributor and rotor and distributor contacts are clean and dry. Distributor has not moved in mount. What is the best way to check for vacuum leaks?
 
#14 ·
Pinch your vacuum hoses for the one that does not cause the idle or sound of the car to change. Have you tried actually listening (with stethoscope or rubber hose) to each of the cylinders to hear them?
 
#15 ·
I'll try the vacuum hose technique. Am I correct in that the pinched hose that results in no change is the potential culprit? Also, I recently purchased a stethoscope at "Horible Fright" for diagnostic purposes. What should I be listening for with the engine running? I'm trying to not let the engine run too long, a few minutes at most, so that the cat doesn't heat up and consume itself with the extra unburnt fuel. Should I continue this approach?
 
#16 ·
Yes, the pinched hose that causes no difference will be the one with the problem (or the circuit with the problem).
With the mechanics stethoscope, you should be able to hear where your 'duh duh duh' is coming from. Start by the cylinders.
Have you ever done a compression test on the engine? Doing so may also lead you to your problem cylinders, as well as checking the timing for you.
 
#17 ·
I pinched all the hoses I could find. The only one that made any difference (the engine almost died) was the IAC hose connecting the IAC valve to the intake tube between the air cleaner and the throttle butterfly. There was no change in idle characteristics with any of the onter hoses being pinched. I listened with the stethoscope and all of the cylinders sounded identical with a steady, repetitive "tapping" and all of the fuel injectors sounded identical with a steady, repetitive "clacking" sound. There was no appreciable difference between the individual cylinders or injectors. Just for fun, I also listened to the cam cover and the distributor. They both had a "whirring" sound with no spikes or variations in intensity or grinding noises. The car continues to throw "P0300, Random Cylinder Misfire" codes. Thoughts?
 
#18 ·
Is it actually misfiring?

I see you listened and you heard everything operating normally (good move btw) but if you sit in the car can you "feel" a misfire? I have not personally ever had a false positive on a misfire, but I am sure it's possible.
 
#19 ·
Yes, there is a distinct difference between the way it idles and runs now and how it idled and ran prior to this issue surfacing. It was very smooth before at all RsPM and now it is a steady and "lumpy" or rough idle and distinctly rough at all RsPM. Since I just replaced the battery a few days ago, today I also replaced the post clamps with nice shiney new brass ones since the original + and - clamps were corroded badly. No difference in idle characteristics, IE still missing.
For review: Distributor and rotor clean and dry, no cracks; new plug wires 3 days ago; spark plugs all identical appearance and all gapped at .028; loosened and tightened engine bay grounding nuts; hose pinching results just above this post; timing at 5 degrees BTDC.
The only correlation I can think of is that just prior to this whole issue starting I sprayed the car off aggressively and probably sprayed into those little hood side vents just forward of the hood pivot attach points. I did WD-40 those contact bundles shortly after that washdown. Still looking. I'm going to try new plugs next.
 
#20 · (Edited)
Use an IR gun and check which cylinder is coolest (exhaust manifold close to head), that should confirm a misfire.....

Connect a vacuum gauge to an un-metered port, this will help diagnose the engine condition and any leak if you have one (I suspect not, as the idle dies off when ISC is pinched off)...... Philip
 
#98 · (Edited)
HF has several Infared Thermometers on sale currently.

We have a new store opening and I have a 20% off coupon code that may work if you order online. PM me if you have an interest.

Infared Thermometer - Harbor Freight Tools

Edit: the poster trying to cool his cabin using window tint could use this to see the diff between black & white roofs temps.
 
#21 ·
Summary so far: New plugs and plug wires; removed, cleaned and replaced the crankshaft position sensor; new battery, new battery terminal connectors; loosened and tightened engine bay ground wires; vacuum system seems intact. Previous plugs #3 and 4 seem to be a bit damper and darker in color than plugs #1 and 2. They also had a slightly stronger smell of gas. I'm reasonably confident it has air and fuel, it seems the spark is the (random) missing ingredient.
Could water sprayed on the two wire bundle connectors that sit just above the brake master cylinder have been the cause of this problem? If so the event was over a month ago. Wouldn't they have dried out by now?.
What's left? Distributor issues? Bad igniter, etc? Cap and rotor checked clean, dry and no cracks or deposits or indications of burning.
 
#23 ·
Has burned valve(s) been ruled out?

How many miles on this?
 
#24 ·
This problem surfaced suddenly - the car was running fine, I shut it off, I started it 2 days later and it started with stuttering idle and a "P0301, #1 Cylinder Misfire". code. I shut it off and worked on the rear end for about a month and started it again and then it showed a "P0300, Random Cylinder Misfire" code. In between running fine and the first indication of a problem I sprayed some water into the hood side vents. Wouldn't a problem resulting from a burned valve have happened more progressively and not from one start to the next? I do appreciate the inputs but the problem source seems to more electrical than mechanical in origin and onset characteristics. Am I on the wrong track here? Frustrated in Texas!
 
#25 · (Edited)
Tell me how a burned valve would manifest itself? What are the symptoms?

So for other auto problems? It was fine, I drove it here, parked then it wouldn't start?

I take that to mean no a burned valve has not been ruled out. I am not saying that is the problem -just asking if it has been ruled out.

btw - ruling out the obvious is how doctors determine what is wrong.
 
#27 · (Edited)
Finally back at it! Compression test, cold engine, WOT - #1-183, #2-180, #3-178, #4-180. Visually inspected T-belt, crankshaft/cam timing agreement, manually checked valve lash, disty/rotor spot on, #1 cylinder timed to 1 o'clock post, plug wires sequenced accurately, new plugs and plug wires. Before (1 month ago or last time I was able to work on it) car would idle roughly with obvious misses. Now car will not even idle. I don't think the valves have burned any more since then while sitting in the Texas sun. Texas is hot but it hasn't been that hot. Thoughts?
 
#28 ·
I would think the compression values would be lower if you had a burned valve or cracked head.

Have you checked the distributor cap for cracks? Is it new?

Was the vacuum checked? Any readings there?

May be time to check your computer. Any codes there?
 
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