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rxb
Novice
Mar 6, 2016, 6:18 PM
Post #1 of 17
(1481 views)
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Misfire Conundrum...
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1999 Toyota corolla (1.8L, 1ZZFE eng) 150k miles
original symptoms/problem :
1.very rough running and vibration at idle - seems to run better above 50mph though I only drove it enough to get home because of a...
2.Blinking check engine light
3.some oil seeping out of valve cover gasket on exhaust side (no oil in spark plug wells) - pre-existing
testing :
misfire confirmation
on my way home after the problem started, I did stop by autozone to pull the codes - only 1 code, P0301. I confirmed that it is indeed only cylinder 1 with 2 separate tests - both temporarily pulling the spark plug boots one at a time and then pulling the fuel injector electricity one cylinder at a time, as well. Cylinder 1 had no change, all other cylinders dropped idle to the point of almost stalling for both tests.
result : only cylinder 1 misfiring and seems to be misfiring every time.
spark
the spark plugs had a little carbon build up and two of the spark plugs had a very small amount of oil on the threads and electrodes. I replaced all four and this does not fix the misfire.
I check all four cylinders with an inline spark tester; all four are getting spark. I also tested the plug from cylinder 1 out of the cylinder to see that it can produce a pretty good intense arc. At least half an inch through air.
result : spark is good all around
compression
compression test shows 175psi,165psi,170psi,170psi for 1 through 4, respectively.
result : all four cylinders are holding compression
vacuum leaks
First, I used propane to test for vacuum leaks all around the engine. No difference in idle. And then starter fluid to spray around the intake manifold concentrating on where the manifold meets the head for cylinder 1. Again, no difference in idle.
result : no vacuum leak (?). I would guess that a major vacuum leak would lead to random misfire and not the specific and consistent cylinder 1 misfire that I am seeing. if I understand things correctly, the only way a vacuum leak could lead to a single cylinder misfire would be if it was in that cylinder's portion of the intake manifold gasket, right?
fuel
I tried to do the "screwdriver touching the fuel injector" test to listen for ticking/clicking, but the engine vibration and wobble at idle makes this inaudible. with the key in start, I see a voltage of 12.38 from each of the fuel injectors electric cables. And then .44ohms back to battery through the negative side. Electrical connections are all solid. The resistance across the four injectors themselves was consistent (13ohms)
I pull all injectors and clean them manually. I see 4 solid streams from each injector. Just to be certain I swap the injector from cylinder 1 to cylinder 4. No change. Still cylinder 1 misfiring 100% of the time.
other
Even though the valve cover gasket is seeping oil out of the side and not into the spark plug wells (that I can see), I go ahead and replace it. It covers my bases and was something I needed to do anyhow. no change.
So, long story short, I think I have spark, fuel, and compression for all four cylinders. Argh...
I feel like there are parts of the system that are in parallel - spark plugs, wires, injectors, etc. That is, one separate thing for each cylinder. And then some things are in series. Gas tank - fuel filter - fuel pump...or air filter - throttle body - intake manifold.
My assumption is, any problem in series affects all cylinders equally. Any problem in a parallel component would affect only that particular cylinder.
So with this series vs. parallel logic (and the fact that there are no other codes), I ruled out EGR/IAC/MAP and such as I would think these would give more random misfires and be across multiple cylinders, no?
And I very distinctly have only 1 cylinder misfiring and it's all the time.
I must be missing something!
If my fuel pump were on the fritz, would it pump enough fuel to the first three injectors, but not enough to the fourth?? Cylinder 1's injector IS the farthest down the fuel rail. I guess it's not impossible(?). Can I simply pull the fuel rail out and have someone crank the engine to see all 4 sets of injectors streaming? I guess the proper way is to test fuel pressure long before the injectors, though I don't have such a pressure gauge.
Or maybe the intake manifold tube for cylinder 1 has an obstruction? I guess this would prevent enough air from entering the cylinder but not yield a vacuum leak. No clue how that would even happen. I can't find detailed diagrams of the intake manifold interior to see at what point it switches from series to parallel.
Any thoughts or suggestions would be greatly appreciated!!
-rxb
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Double J
Veteran
/ Moderator
Mar 6, 2016, 8:40 PM
Post #4 of 17
(1457 views)
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Re: Misfire Conundrum...
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Eliminates the Injectors by swapping them but you still have to see if the PCM is pulsing the Injector
The PCM will send ground to the Injector when its time to fire that cylinder
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rxb
Novice
Mar 6, 2016, 8:56 PM
Post #5 of 17
(1454 views)
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Re: Misfire Conundrum...
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gotcha, as I see pictures of the noid lights, I see that they have nothing to do with the injector itself. in hindsight, my simple voltmeter test is not robust enough to see pulses over time (like an oscilloscope might). I'll find a noid light set and get back with you. thanks!
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Double J
Veteran
/ Moderator
Mar 6, 2016, 9:06 PM
Post #6 of 17
(1452 views)
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Re: Misfire Conundrum...
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OK Cool, Let us know
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rxb
Novice
Mar 7, 2016, 9:49 AM
Post #7 of 17
(1429 views)
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Re: Misfire Conundrum...
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Noid light flashing with similar frequency and intensity across all 4 fuel injector wiring harnesses. I believe that rules out PCM and wiring issues, yes?
Clarification- when noid light is in cylinders 2-4, it flashes ever so slightly slower. Guess this is to be expected as now the engine only has 2 cylinders firing and the idle speed drops even more, so injector pulse should slow a little as well.
(This post was edited by rxb on Mar 7, 2016, 9:55 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 10:25 AM
Post #8 of 17
(1421 views)
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Re: Misfire Conundrum...
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? Just some things that have caused this - asst engines for me:
Deep well plug wires can and do jump out of the side of plug wire unseen but will check well with an in line spark tester. Some you can see where it's jumping out of as a very small spot on the hard, longer part of wire to plug?
Another with ONE dead cylinder was a plug itself w cylinder somehow so wet a new plug didn't fix it till it dried out quite a while with plug(s) out? Somehow spark still chose wet metal inside cylinder - rare but has happened a few times.
Another is if stuff all apart losing track of firing order more common mistake with distributor ignitions follow direction of engine rotation. Oddly can run and somehow pick on one cylinder. If two totally off engine shouldn't stay running or usable to drive on 4 cyl engines.
Last other: Wrong brand of spark plug - OE only, none with fancy claims of being better or good enough - no, no, no,
T
(edit late - firing order is 1342 if messed with double check. Engine firing direction should be counterclockwise matters!)
(This post was edited by Tom Greenleaf on Mar 7, 2016, 10:34 AM)
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 10:26 AM
Post #9 of 17
(1419 views)
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Re: Misfire Conundrum...
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Inspect the plug wire boot really good. Check for burn through. Spark that pops out the side of the boot inside the spark plug well won't allow spark through plug. With that mileage if the plug wires are original it is probably time to replace them anyway.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 10:38 AM
Post #10 of 17
(1416 views)
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Re: Misfire Conundrum...
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Both hitting DS. I seriously think that is the problem with this type plug wire. Just edited my above post not for that. They absolutely can jump outside that wire with almost no visual evidence and test fine if not connected to the plug but just ground. CEL verifies this is totally not firing to me,
T
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rxb
Novice
Mar 7, 2016, 12:07 PM
Post #11 of 17
(1404 views)
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Re: Misfire Conundrum...
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plug wires were replace about 3 years ago, still look quite new. resistances - from longest to shortest - were 1100,1000,900,800ohms respectively. (don't have the exact numbers in front of me, but that's ballpark if memory serves), so they seemed solid to me.
the new spark plugs were identical to the ones that I replaced (that worked fine for the last 3 years), pretty sure they were OEM, anyhow. (though I would need to be at the vehicle and see the new box to remember the exact ngk# for confirmation).
the spark plug wells themselves were dry, with only a very slight amount of burnt, wet oil on the plug threads and electrodes of two of the plugs (cylinders 1 and 4). of course this small amount of oil had to come from somewhere. with the compression tests being good, I guess it was seeping out of the valve cover gasket, which has now been replaced. I'm pretty sure I gave the cylinder head a spray of wd-40 before replacing the spark plug (to displace any remnant oil that might have been in the threads). I suppose I can pull the cylinder 1 spark plug and let it "dry out".
the car appears to have two coil packs mounted on the side of the engine (each pack has two spark plug wires connected to it. I haven't messed with any of this, or anything else that would throw off the timing, I believe.)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 12:36 PM
Post #12 of 17
(1401 views)
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Re: Misfire Conundrum...
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I do apologize if I'm adding to confusion or the mess with this. Old phart here, even local shops would give me this bull as they didn't have the time and I didn't care and did.
Found testing leads you the wrong way sometimes. It's somehow a common issue with those plug wires with the hard long stretch going to the plug that really can test right and totally jump spark out of it.
IDK - Hillbilly trick. Put a spark plug in the plug hole or leave the one that's there, pull that wire and ground that wire with a nail to dead ground for a test. It is now totally happy to be grounded and nothing may show. Same as with spark tester (preferred) now ask it to jump a 1/2 inch spark or even less, bet it shows good. Now wet the thing with salted water spray and hold a good grounded jumper wire to it and watch - it will probably select the jumper wire thru the side of the extension that would be to the plug. The issue IMO is that it's close to ground metal while installed so you don't see it fail. Could be new out of the box and fail too!
Another engine but same deal did this so much I kept spare single wires at less than the 3 year mark! Nobody touched anything to cause it? Then they quit selling just ONE wire so I was keeping all but the bad one of a set if only to get someone thru for a while or some it ran perfectly for ages but didn't run too long on a dead cylinder spewing raw fuel at converters so anything was better if only till parts came in for another day.
It's just my hunch that this is just that and that easy for a fix. May take some luck and time if converter ate too much raw fuel to fail or clear out? Another day for that if at all?
T
NGK was the plug maker I would have said was right and didn't go there.
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 1:09 PM
Post #13 of 17
(1396 views)
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Re: Misfire Conundrum...
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One way you can test to see how insulated the spark plug wire boot is is to install your inline tester and set it to around 30KV or 3/4 inch. Then disable the fuel injector for that cylinder, so your not putting raw fuel into the cat. Take a 12 volt test lamp connected to ground and run the probe around the plug boot. If there is a spark leak, it should find your test lamp.
The spark should be able to jump more than 3/4 inch.
With the engine running, does the exhaust smell gassy? Like raw fuel?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Mar 7, 2016, 1:11 PM)
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rxb
Novice
Mar 7, 2016, 2:11 PM
Post #14 of 17
(1389 views)
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Re: Misfire Conundrum...
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I'll be a little more thorough on my plug wire inspection when I get home, and then get back to you.
I wonder if I could wrap the boot in some kind of insulator for a quick test? electrical tape? (nothing I'll keep on it for long, mind you, just to see if the cylinder starts firing...)
edit - haven't smelled any gas in exhaust, but then didn't stick my nose over there either. raw fuel out the exhaust and burning in cat will smell super obvious from a mile away or just a subtle gas smell? again, i'll let you know once I get home.
(This post was edited by rxb on Mar 7, 2016, 2:19 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 4:01 PM
Post #15 of 17
(1382 views)
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Re: Misfire Conundrum...
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If trouble testing or see that wire can you swap it with another. The tricks of tape, liquid electrical brush on tape for me haven't worked at all as it's too close when installed.
What makes these things fail is probably an original defect because the ones that did, did it young and some lasted the life of a vehicle? Of course none like being mishandled now or before you buy them either.
Just me I think sometimes but if buying new stuff will refuse damaged boxes for electrical things that carry high voltage.
Again if it is this you may not see it without testing as suggested or swaptronics with one that's known fine if possible,
T
(edit) You aren't smelling raw gas probably because cat converter is burning it up in the exhaust system but wont forever......
(This post was edited by Tom Greenleaf on Mar 7, 2016, 4:02 PM)
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rxb
Novice
Mar 7, 2016, 7:42 PM
Post #16 of 17
(1370 views)
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Re: Misfire Conundrum...
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son of gun if it wasn't that spark plug wire (boot) after all.
thanks for your help fellas, much appreciated! Case closed!
if readers care to see why/where my tests failed...read on....
those plug wires were quite new (3 years or less), didn't show any signs of physical damage or wear. no scarring, fraying, melting, or burn marks. could probably put these suckers in a new box and sell them, and people likely wouldn't notice (well, until they installed the cylinder 1 wire, anyhow). resistance was on target and it was consistent no matter how I moved the wire around. no reason to suspect them.
when I had the plug fitted in the wire and boot outside of the cylinder, it worked just fine. I grounded the threads, and it happily lit that plug up like I would normally expect. the boot must have been far enough away from ground that it had no choice but to go through the spark plug.
the in-line spark tester actually worked as it should. why? because it's boot was sound and not compromised. the upper part of the spark tester connecting to the actual wire boot was now so far in the air that it couldn't find a ground by arcing out of the defective boot. but here's the kicker...at that point I was only testing for spark. and I was so afraid of dumping raw fuel into the cat, that I had the fuel injector unplugged. so for that brief period of time, I had the spark fixed but fuel was off! if I had had the fuel injector plugged in, I would have seen that the misfire cleared and steered straight towards the difference - the new setup involving the tester. At this point I would have (reluctantly) swapped wires (like I did just now) and seen the new cylinder now misfire, absolutely confirming it was that one plug wire.
long story short, when you have only one cylinder misfiring and it's misfiring all of the time(?) then just swap everything you possibly can (if it looks good or not) right from the start. seems obvious in hindsight, but I was stubbornly assuming a relatively new wire couldn't be the problem. Argh!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 7, 2016, 11:28 PM
Post #17 of 17
(1362 views)
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Re: Misfire Conundrum...
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Thought so and said they could be "elusive" + work when tested, not work while installed.
BTW - some did this when whole cars were new also and off warranty that soon?
Glad it's fixed. Closing thread as solved to keep spammers out. YOU may ask any moderator to re-open it upon request,
T
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