New owner, misfire issue

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O

oakback

10 Year
Joined
Apr 14, 2015
Threads
62
Messages
570
Location
Tallahassee, FL
I bought my 100 series on Wednesday, 163k miles. Check engine light was on, running a bit rough, PO said it was a coil. I had codes check, misfire on #3. Swap coil with #1, clear codes, CEL comes on, still coil #3. So I replaced #3 spark plug. Clear codes, CEL comes on, still misfire on #3.

I removed and reseated the electrical connector for the injector, just to make sure it was seated all the way on, and it is. I searched some, and the next thing I'm going to do (when I get home tonight) is check resistance on the fuel injector for #3 (should be between 13.4 and 14.2 ohms, right?). I was also planning on dumping a can of seafoam in the tank when it's half full.

PO said he was using regular unleaded gas ("I never noticed any difference"), I'm guessing he'd been doing this awhile. I filled it up with premium, it was almost on E when I got it.

So, am I on the right track? What else should I try?
 
You can't edit your post because you don't have enough posts yet. You're on the right track I would move forward with what you're doing. Since you know there's no issue with other injectors you could check the resistance it's one of those and see if it matches what number three is. I don't have that spec in front of me, but maybe somebody else can provide it.

Have you checked with a noid light to see if you're getting injector pulse on that cylinder, and have you checked to see if the coil is actually firing?
 
Thanks, I'll do that with checking the resistance.

I'm not familiar with a noid light or how to use it (I've never heard of that).

I just remembered I have a spark tester (the kind you plug in between the plug and boot and lights up if there's spark), I'll try that if it fits.
 
A noid light is simply a light attached to two prongs that fit into the pigtail that attaches to your fuel injector. You could do a makeshift noid light with a 12v 194 style bulb, two alligator clip wires, and a two bobby pins.

All you do to see if you have injector pulse is attach the noid light, then crank the engine while watching the light. You should get a semi-rapid flashing.
 
I wouldn't look to the lack of premium as the root cause of your issue. But other than that I think you're on the right track.
 
I'm 98% sure it's the fuel injector. Measured 0 ohms, with the other measured 16.5. Additionally I used a long socket extension to listen to the injectors. 2 of them had a very audible ticking, but #3 only ticked occasionally. Looks like I'll be changing out that injector.

Is there anything else I should bother with while I'm taking that out?
 
Good that you found it quickly, and it sounds like you have some troubleshooting experience. Not many people think to listen to the injectors.
 
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