LT 1 strikes again!

Old Jul 3, 2022 | 08:53 PM
  #1  
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Default LT 1 strikes again!

Ok. 94 lt1, keeps fluttering and backfiring unless I'm WOT. Any ideas? Nothing more embarrassing than pulling through my neighborhood foot on gas and brake, exhaust screaming just to get her home!🤣🤣 It will idle just fine, but after a hard takeoff onto the highway she started backfiring like the 4th of July! Unless i was wide open on the throttle. Just noticed that it is really rich also.
 

Last edited by SleepinZ; Jul 3, 2022 at 09:08 PM.
Old Jul 3, 2022 | 09:49 PM
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rich mix will cause back fire in the exhaust. I would suspect the 02 sensors and injectors first. have a look at the plugs as well. if your getting a non fire cylinder or two it will also go rich.
 
Old Jul 4, 2022 | 11:17 AM
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I was leaning more towards the MAF sensor.... it's about the only sensor I haven't changed out over the last year.
 
Old Jul 4, 2022 | 06:59 PM
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Ok so I unplugged both o2 sensors (at separate times) and started the vehicle. I get a CEL but it still starts fluttering when I give it gas. After each sensor I unplugged I would start the car and try to Rev it, but it still does the same thing. I've done this with the MAF sensor, MAP sensor, IAC, IAT, and o2 sensors. Only one I didn't do is the TPS. I don't have correct diagnostic equipment, so this was the only thing I could think of doing. I wanted to check things out with my multimeter, but that somehow got "lost" in this chaotic house!🤣🤣🤣
 
Old Jul 4, 2022 | 09:40 PM
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test temp sensor, go here, http://shbox.com/1/4th_gen_tech1.html click how to's then look at #20. if sensor is failing it can show a minus temp and cause rich condition.
 

Last edited by craby; Jul 5, 2022 at 12:31 PM.
Old Jul 5, 2022 | 10:02 AM
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Originally Posted by craby
test temp sensor, go here, click how to's then look at #20. if sensor is failing it can show a minus temp and cause rich condition.
🤔 Go here where?
 
Old Jul 5, 2022 | 12:31 PM
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dang link didn't show, fixed it just in case here it is again 4th Gen LT1 F-Body Tech Aids sorry bout that.
 
Old Jul 5, 2022 | 05:01 PM
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No worries. I tried to upload a video, but I guess mp4 isn't suitable? Anyways, thank you for the link. I'll try it out sometime. My multimeter is missing right now.
 
Old Jul 6, 2022 | 06:53 AM
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Just a FYI. Once you unplug one sensor the car goes into LIMP mode. At that point its is running on a predefined fuel and ignition mapping. This mapping works pretty good at 78 degs, at sea level, with a given bar pressure. I believe it still needs the TPS and MAP sensor. But just about everything else is ignored. You won't find this in books but I used to unplug the MAF sensor and if there was not a major change in how the car ran then I would hook up a scope. The thought was if it nothing changed and the base tune would not run right and you do not have oblivious signs of a MAP sensor or TPS then sensors are not your first go to. The issue was probably ignition or fuel delivery.



 
Old Jul 7, 2022 | 07:07 AM
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Originally Posted by Gorn
Just a FYI. Once you unplug one sensor the car goes into LIMP mode. At that point its is running on a predefined fuel and ignition mapping. This mapping works pretty good at 78 degs, at sea level, with a given bar pressure. I believe it still needs the TPS and MAP sensor. But just about everything else is ignored. You won't find this in books but I used to unplug the MAF sensor and if there was not a major change in how the car ran then I would hook up a scope. The thought was if it nothing changed and the base tune would not run right and you do not have oblivious signs of a MAP sensor or TPS then sensors are not your first go to. The issue was probably ignition or fuel delivery.
I'm definitely starting to think that there is something with the ignition. It will idle, but backfires and cuts out at part throttle, but wide open there are no issues.
 

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