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Discussion Starter #1
Replaced distributer cap and rotor as well as plugs and wires, did not change a thing. Tested for spark from cap and wire and plug all spark is good. Did compression test, all cylinders read at 150 within 3 cranks. Compression is good and spark is good so I’m replacing the injector with the ACDelco mpfi Spider unit and I’m pretty positive this will fix the problem. My only concern is that I can’t afford the new unit for about a week and I have to drive my truck to work and back every day (about 20 mile round trip). Will driving with that cylinder misfiring cause any other problem? The drive-ability hasn’t changed much but the sound makes it very noticeable and I can notice a small power loss as well as it shakes at idle. Is it safe to drive for the next week until I can buy the new injector unit?
 

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I assume you're dealing with a 1996+ L35 but for future reference, you should specify the year and engine for both diagnostic and search purposes.

Did you compression test with the throttle blade held open. 150 is a tad low, but about normal with the throttle closed.

Lift up the distributor and carefully examine the entire cam drive gear on the bottom of it. You're looking for wear. on the gear faces. It'll be fairly obvious if it's bad. Double check your wires.

RF 2 4 6 coil
LF 3 1 5
 

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Since #3 is the hardest one to get to, there is a good chance the plug got cracked when replacing it. If you remove the bottom bolt on the steering shaft and swing it up and out of the way, #3 is a lot easier to get to.
Depending on what year, that shaft is easily removed completely for access to that side of the engine.
 

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Discussion Starter #4
Sorry about that, did not realize. 2000 s10 4.3 Vortec ( L35 )vin w. Number 3 plug is 100% not cracked and it is not hard at all to get out or back in with a 10 inch extension and u joint plug socket. About 2 weeks ago I Changed #3 plug out with acdelco iridium to see if that was the problem, it was not. The plug was very fouled but changing it didn’t fix the miss. So I put a brand new plug in that cylinder a little less than 2 weeks ago and yesterday I changed all the plugs out for acdelco iridium plugs including cylinder #3 and the 10 day old plug I pulled from it was fairly fouled. Along with the plugs I changed cap, rotor, plugs, and wires. No change with miss. As far as the compression test I was not specific at all my bad, Throttle blade was held open, fuel pump was disconnected and spark coil wire was grounded. For each cylinder I cranked a total of 7 times and the final reading was between 175 and 180 PSI for each cylinder.
 

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Discussion Starter #5
Wires aren’t crossed and plug is definitely not the problem, I do think you are on to soemthing with the cam drive gear, definitely gonna take a look at that for wear when I get off work.
 

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Discussion Starter #6
I also would like to mention that cylinder 3 only started missing after I had a shop replace the intake manifold gasket. Not after the gasket went bad, but after I got the truck back from the shop. First start up it was shaking and missing bad, this leads me to believe they broke #3 poppet on accident or without noticing or maybe it just went bad not too sure.
 

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I'd take it back to the shop and tell them it started running bad after the gasket replacement.
 

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Discussion Starter #8
I took it back the next day, they told me it was the plug, “changed” plug 3 and it still misfired so he told me that it had low compression on that cylinder and to drive it till the motor died. That cylinder is very much not low on compression and also they did not change plug 3 they changed plug one, because on the distributor the order is 315 I think he got confused and thought he had the right plug. Anyways the gasket they put in is good. But I don’t trust them to work on my truck again haha and I also do not want to give them any more money. I’ll fix this problem myself then never take it to a shop again. Call it a 300 dollar lesson learned. My main concern is if driving it while it’s misfiring till I fix the injector will damage the motor.
 

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Regardless of what is on the distributor any idiot would know the difference between the front plug and the middle one.
Sounds like you got it all figured out. Good luck fixing it.
 

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Discussion Starter #12
More likely to damage the transmission, actually.
Sorry I always forget to reply. Can you educate me on how this will affect my transmission please. I have been driving it now to work and back about 15 miles with it misfiring considerably For about 2-3 weeks. I received the mpfi conversion spider injector in the mail but I have yet to have the time to pull the old unit and install this new one. My main concern with these posts has been wether or not driving the truck with it running in the condition it’s in will affect the motor (or truck in general) at all.
 

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Can you educate me on how this will affect my transmission please.
It came up in a youTube channel: Precision Transmission
The misfires cause the steels in the low reverse clutch tangs to bang into the aluminum of the case and chew it up. Left too long, they eventually spin, but before that, a bunch of aluminum debris circulates through the pump and makes a mess of it and a couple of the valves in the valve body.
 

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Discussion Starter #14
Got the new spider in truck is back on all 6 and running better than it ever has. Appreciate everyone for the help
 
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