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Intermittent miss
Topic Started: Sep 18 2011, 03:49 PM (2,572 Views)
Maas562
:)

Alright well, I put on a new cap and rotor. The wires and plugs were new back in May as well. The miss has definitely gotten better but it is still there. Before it was so bad that I could hardly accelerate, now it is just a small "hiccup" while accelerating through the lower rpm's.

Any ideas what to try next?
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Coche Blanco
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Troll Certified

Compression test...
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JellyBeanDriver


What brand and type of plugs?
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Maas562
:)

Champion RN12YC
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Bad Bent
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Facetious Educated Donkey

If this is a 1.0 then the plugs may be wrong. :-/

For my '91 at http://www.sparkplugs.com/results_app.asp?aaia=1430188 it lists:

Champion....Traditional spark plug..... 322........ RN11YC4.... .043
Champion....Single Platinum................ 3322..... 3322...................... .044"
Champion....Iridium Plug....................... 9804..... 9804....................... .044"

We have not had a lot of Champion users. The recommended plug would be NGK: BPR6ES-11 or in Platinum: BPR6EGP
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92MetroMan
Fresh Fish
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Maas562
Oct 9 2011, 09:17 PM
Alright well, I put on a new cap and rotor. The wires and plugs were new back in May as well. The miss has definitely gotten better but it is still there. Before it was so bad that I could hardly accelerate, now it is just a small "hiccup" while accelerating through the lower rpm's.

Any ideas what to try next?
I'm in the same boat as you with my 92 1.0
Exactly the same issues. Damp mornings are the worst.
I've done all that was suggested here before I found this while searching for help.
Except I used Sea foam not Marvel Oil & I changed my fuel filter too. :banghead


I'm wondering if its the fuel pump or the Ignition coil?
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Bad Bent
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Facetious Educated Donkey

Dampness, moisture... try this;


And it may not be plug wires but the coil wire that spraying a fine mist of water/soap on may show a short, or a cracked distributor.

Another thing to do is see if moving the wiring harness causes the intermittent. A loose coil wire or bad ground, like on the TB or even the engine ground?
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Maas562
:)

Alright well, a little update. The miss is definitely still there. It happens now dry or wet. So the weather is out as a factor. In 1st, 2nd, and sometimes 3rd, usually right after I shift and hit the gas it will just cut out for a split second and then come back on. It doesn't do it every time, just randomly.

Here is a list of things done.

Plugs
Wires
Cap
Rotor
Oil
Oil Filter


Last night I did a dry compression test.
#1) 185
#2) 210-220 (maxed out gauge past 200)
#3) 210-220 (Same)

I don't think that slight drop in #1 means anything too significant yet. I actually first did the test without WOT and all 3 were 165psi exactly.

Also the plugs were more of a light white than a tan brown in color when I removed them. Make me think something is causing it to run a bit lean.

I guess I'll try switching to the NGK's now?
Edited by Maas562, Oct 21 2011, 04:30 PM.
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Bad Bent
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Facetious Educated Donkey

Certainly new plugs would not hurt and it is not too expensive as the web sites says $2.89 each. And white is usually an indicator of an additive.

Have you tested the Throttle Position Sensor? It may have a dead spot or it's not set correctly.

Here is a link to a spark plug chart: http://i404.photobucket.com/albums/pp123/BadBent/archive/sparkplugChart.jpg
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Maas562
:)

So I replaced the PCV, and threw in new NGK plugs. It's still there.

I also changed the timing belt and serp belt just because I have no idea if the PO ever did.

Anyways, I think I might have narrowed it down. When idling there is a pronounced clicking coming from the coil. I'm assuming it's normal and just the coil discharging but it caught my attention. So while looking closer at the the coil I could see it arcing.

The arrow in the picture is where the arcing is happening.

Posted Image

Guessing that's not normal. Also if you run your finger down the coil wire going to the dist cap you get a constant small shock. But if you do the same on the plug wires there's nothing. All the wires are new back in May.
The weird part is the arcing goes away if I mist it with water.



Thanks
Edited by Maas562, Oct 23 2011, 08:01 PM.
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idmetro
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Arcing from the coil is definitely NOT normal. I'd say you've found you culprit - swap out the coil and I bet your problem goes away. Keep us posted.
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Maas562
:)

Will do, I just started it up in the dark and took a peek under the hood. It was light a mini lighting storm under there. The coil had arcs all over and the coil wire would arc to anything it touched. Must be some junk wires because I just put those on in May
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JellyBeanDriver


Yay! I too think you found it!
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Maas562
:)

YAYY! I put in a new used coil and coil wire. The miss is now gone! Thanks for the help!

:cheers :thumb :drivin :banana
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Good bye


Good job solving your missfire. I hate high voltage leaks, of course I work for an electric utility. Now wind storms = $$$ but that is another story. Hold on here comes another El-Nino season in the North West.
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