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Have you used a spark tester to actually verify spark to each cylinder? If u just threw new plugs and wires at it then it may be one of two coil packs. Cut a piece of clear tubing abt 3/4 inch long, place in between plug wire and coil pack and start and look for a good spark. Do this on each coil in the pack. Also spray down Block with water and with lights off watch for arching from boot to block. If miss is only under heavy load then spark takes number one suspect on my list. I had a ranger with a bad coil pack which did the same thing under heavy load. It was a bad coil pack and wire boot.
I hear u can take a coil pack to an automotive store to test. …i do the test from the coil to the plug wire in the garage with the clear tube. Look at good cylinder spark and u will see a difference between a good and bad spark. In short, I’d check coil packs.
Real fixes real fast has a video on diagnosing a misfire without a scanner that may help….YouTube it.
[quote=”bbryan1″ post=82091]I hear u can take a coil pack to an automotive store to test. …i do the test from the coil to the plug wire in the garage with the clear tube. Look at good cylinder spark and u will see a difference between a good and bad spark. In short, I’d check coil packs.[/quote]
They usually can only test ignition modules, and to be honest the automated testers are not that good.
TO test a coil it has to be stressed, a spark tester is the single best way.
When you have a misfire the check engine light flashes. A misfire can cause the catalytic converter to overheat and cause damage to it.
[quote=”kodiak341″ post=82139]Ok…I dont have a spark tester..guess I could go buy one…would a multimeter work the same??[/quote]
No you need something like this
http://www.uniquetruck.com/p-17256-electronic-ignition-spark-tester.aspx?affiliateID=10056&gclid=CM6p2PzvrbsCFUho7AodwWsApQSome people take a plug out, put it in the wire and lay it on metal to see if the coil is good. Don’t do that it is a unreliable test. It is easy for even a very bad coil to fire a spark over that tiny of a distance in open air, the coil basically does not have to work. Inside the combustion chamber there is a ton of air movement and changing conditions, it is actually much harder for the coil to fire the plug when the engine is running than it is when the plug is in the outside air.
The spark tester has a calibrated gap that simulates the workload it would see under operating conditions.
I showed one of techs years ago on a car we had that had a dead miss on acceleration (when the secondary ignition has to work the hardest to fire the plugs) took the wire off, put a plug on it and it fired a beautiful blue spark. Took the plug out put a spark tester in it and no spark. New coil and the spark tester was firing a beautiful blue spark and the miss was gone.
Here is 2 of the ones I have (the one like in the link I sent you my brother borrowed) you can see they are adjustable to see what voltages the spark is firing at.
I had one like this, loaned it out and never saw it again it allows you to test all the wires at once
http://www.ebasicpower.com/p/CDI511-9766/Most likely is a bad coil. Given that the miss happens under heavy load. A spark tester isn’t expensive and any auto parts store would have one. There’s a few different designes. But you can check the coil pack without a spark tester. Since uve got new wires then I’d just test the coil packs. A piece of clear tubing abt 3/4 of inch long that fits snug around the wire but on the coil pack is all that’s needed for this. Realfixesrealfast, diagnosing a misfire without a scanner will give you a visual on how to to do this. Un basically putting a gap between the boot and coil and looking for spark when it’s running.
The check engine light flashes when there’s a severe miss. I used a spark tester to simply isolate the cylinder then swapped a known good wire with the suspected bad wire and got the same bad spark. This lead me to the coil pack. I tested the coil pack by putting a gap between the plug boot and the coil while running which verified that indeed the pack was bad on that cylinder.
In short, with some diagnostic work I didn’t have to replace plugs and wires. I checked the resistance of the wire on the bad cylinder with a known good wire and after swapping them I was able to rule out bad wires. Once plugs are verified as good, and wires are verified as good, then logically the next step is the coil pack. I only use the clear tubing b cuz I want hands free testing of spark. I’ve been bit before and it’s not worth it in my opinion.
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