Can't figure out this misfire

OfnaRcR4

Shea!
Oct 2, 2006
1,340
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kettering ohio
Background of car:
560 injectors/walbro/lexus afm drilled out j tube. No regulator or tuning. Ran alright for about a year and a half so i don't know if has anything to do with me not having a tune or a regulator.
I just have a light miss at any rpm. I first noticed it during a drive in heavy rain. Engine seems to get pretty bad gas mileage but that could just be me. Fires right up upon cranking so idk about a leaking injector. Pulled the plugs and the first three front plugs had quite a bit of oil on them (leaking valve cover gaskets and also valve seals) so i decided to replace them. Autolite 3923's gapped to 25 thou. Tested the wires resistance and inspected them and they seemed fine. After putting everything back together the miss is still there and is no better. Tryied to test what cyl the misfire is at and every plug seemed to effect the engine the same.
Any ideas would be appreciated!
 

mecevans

Supramania Contributor
Jan 18, 2009
1,295
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M-bay, cali
Test your coils and ignitor, is it properly grounded? Are you valve clearences within spec? Any EM noise from you alternator?
 

hvyman

Dang Dude! No Way Man.
Staff member
Apr 17, 2007
12,568
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Fullerton,CA
I would ditch the auto lites and get ngk coppers. but thats me.


So you pulled the plug wires to see if the engine would change or not? What about injector clips?
 

OfnaRcR4

Shea!
Oct 2, 2006
1,340
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0
kettering ohio
I haven't gotten a chance to properly test my coils or ignitor yet but that is next on the list. Been very busy lately. Both coils and ignitor have been re-grounded. Valve clearences should be alright although I've yet to measure them. Not making much noise at all. I'm trying to figure out how to pull injector clips with the 3000 pipe/TB hooked up, how does one do this?
Also I guess I could include that I've got an EGR code that I've had for a while now but is hasn't seemed to effect anything much.
 

OfnaRcR4

Shea!
Oct 2, 2006
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0
kettering ohio
Tested the coils and they all checked out as per tsrm. Aside from an injector problem i am a bit lost as to what it could be. All injectors appear to be firing and they all have voltage but some do seem to be more "noisy" than others. Going to check resistance when i get a chance.
Here's a video showing what it's doing:
[video=youtube;8Xj7ldq2W6Y]http://www.youtube.com/watch?v=8Xj7ldq2W6Y[/video]
[video=youtube;ynM83ADq_z8]http://www.youtube.com/watch?v=ynM83ADq_z8[/video]


It's not really an extremely noticable miss as you can see.
Also, please exuse the spark plug wire zip tie. Although that would seem like a "duuuuh" it's right there, i am not convinced it is. I might get a new set of wires though just in case, i just hate wasting money.
 
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OfnaRcR4

Shea!
Oct 2, 2006
1,340
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0
kettering ohio
Well i still haven't figured out this damn miss yet. New plug wires, no change. If anyone has any ideas on what to check next i'd really appreciate it as i am completely stumped. I have access to an oscilloscope if that helps.
 

Turbo Habanero

New Member
Apr 28, 2009
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Tucson,AZ
i have the same problem.

My miss is more of a bucking at steady throttle not under wide open.

I am too running lexus afm and 560cc i also am getting codes 71 and 41 but only just recently.

I am sure my bucking is coming from the type of filter adapter i have on the AFM but not 100% sure
 

Turbo Habanero

New Member
Apr 28, 2009
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Tucson,AZ
jetjock;1817146 said:
So you're sure but not sure. Got it.

The 71 is not important but the 41 should be fixed...

For me it i have had this problem before about 6months ago oddly my car threw these same two codes together i replaced my Tps sensor and repined the clip and problem disappeared until a couple days ago.

My check engine light comes and go's pretty often while driving it will shut off every time i come to a idle.

But the car's behavior does not change i have also had the bucking issue before i started to throw code 41 again.
 

OfnaRcR4

Shea!
Oct 2, 2006
1,340
0
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kettering ohio
Finally an update. Got around to re-checking the base timing and while doing so i noticed something odd. Hooked up to cyl 6 the light lit quickly, the way you'd expect it to normally.. but when i hooked up to cyl 1 it went half as often, still at a steady pace just half as fast. Bad coil? Ohm'd it and it read 6ohms (spec is 3-5)
 

OfnaRcR4

Shea!
Oct 2, 2006
1,340
0
0
kettering ohio
I'd like to correct myself on that last post. I meant to say .3-.5 and .6 ohms:p Anyway, replaced the coil with a known good one and it didn't fix it. I'm about out of ideas here:O