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My Chevy has been misfiring recently. Done spark plugs, wires, distributor cap, cam sensor, crank position sensor, fuel filter, adjusted timing and everything. Took it to a shop and recommended the spider injector but the part has been updated. I put it in and the misfiring is gotten worse. (Yes the injectors are clean and installed in the proper places) So my question is, do you think I need a new ECU? Since this being such a newer design the older ecu might now be able to read it correctly?
Just trying to get some answers because all my codes have disappeared from my truck but the misfire is still there. Ran a compression check and that was fine too. The only thing I haven’t replaced is the distributor itself but that’s currently on order I just wanna know if y’all would think a new ecu might need to be purchased too.
 

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Whiskey, if you have a misfire there should be codes.
The fact of no codes (i assume no CEL as well) makes me wonder if you have a different problem that feels like a mis-fire.
 

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Discussion Starter #3
Whiskey, if you have a misfire there should be codes.
The fact of no codes (i assume no CEL as well) makes me wonder if you have a different problem that feels like a mis-fire.
after test driving it the misfire code came back. I meant that I cleared all my other codes that were present on top of the misfiring code. Sorry for the wording
 

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I would wait until you get that new distributor installed. That worn drive gear can cause some goofy issues. It seems like mine was acting like an occasional miss with the worn gear.

I would also find a tranny shop that will run some pressure tests for you. It can feel like a miss when the trans is acting up. I even had a bad U-joint that made me think I had a miss. It finally blew up and when I installed the new one, the mysterious miss was gone.
 

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Discussion Starter #5
I would wait until you get that new distributor installed. That worn drive gear can cause some goofy issues. It seems like mine was acting like an occasional miss with the worn gear.

I would also find a tranny shop that will run some pressure tests for you. It can feel like a miss when the trans is acting up. I even had a bad U-joint that made me think I had a miss. It finally blew up and when I installed the new one, the mysterious miss was gone.
I’ll give those a shot thank you
 

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It could be the EGR valve. On these motors, the EGR module thingy has a solenoid that adjusts the valve opening. I guess that can go bad, but probably the most common cause of a problem is it getting gunky with debris after a lot of miles. My 98 5.7 developed a misfire (spit) up around 300,000 and I figured that because it seemed to run right except when it spit every so often, that is wasn't a wear related issue. I took it to a dealer and the mechanic put a used EGR on it he had off of something and the miss went away.

They're expensive, or used to be. Maybe go to a junkyard and see if you can find one with not so many miles on it. The EGR is that round black canister in the front center of the intake manifold. Maybe you can clean it out with Berryman's ChemTool or Carb & Choke Cleaner or something. I think I remember from years ago that I read you want to avoid moving the movable shaft & stopper.

EDIT: I first said "PCV" instead of "EGR".
 

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Discussion Starter #7
It could be the EGR valve. On these motors, the EGR module thingy has a solenoid that adjusts the valve opening. I guess that can go bad, but probably the most common cause of a problem is it getting gunky with debris after a lot of miles. My 98 5.7 developed a misfire (spit) up around 300,000 and I figured that because it seemed to run right except when it spit every so often, that is wasn't a wear related issue. I took it to a dealer and the mechanic put a used EGR on it he had off of something and the miss went away.

They're expensive, or used to be. Maybe go to a junkyard and see if you can find one with not so many miles on it. The EGR is that round black canister in the front center of the intake manifold. Maybe you can clean it out with Berryman's ChemTool or Carb & Choke Cleaner or something. I think I remember from years ago that I read you want to avoid moving the movable shaft & stopper.

EDIT: I first said "PCV" instead of "EGR".
Thank you! I completely forgot about the EGR valve. It does smell like its running lean too so that may be the cause.
 
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