Coughing under wide open throttle

Holiiraviolii

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Hello everyone. I have a 97 gtp that is having some issues. I've replaced the plugs, plug wires, map sensor, fuel pump, and O2 sensor. I've had a wideband hooked up to it and it is not running lean, but it keeps retarding the timing under hard acceleration. Any ideas of where to go next?
 

melsg5

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Do you have a check engine light on?
If you run two tank fulls of premium does it still retard timing?
Did you change the knock sensor?
 

Holiiraviolii

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the check engine light codes are for the maf and the O2 when I unplug them. I'll have to look into getting a new knock sensor. Thank you!
 

melsg5

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Do you have codes with everything connected and if so, what are they?
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melsg5

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So your title says "coughing" and your description only mentions timing being retarded which points to the knock sensor . I assume you know the timing is being retarded by watching a scan tool?
Have you done a fuel pressure test? I know you have a new pump.
 
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Holiiraviolii

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Fuel pressure is was reading good, that is one of the things that I checked for previously. And sorry about that, I guess I was a little vague lol. It bogs and stutters, and then dies under full throttle. I'm not the most experienced in working on vehicles, so I am still learning as we go. Before it was mine, it belonged to my grandpa who flips cars. According to him, the O2 sensor seems to have been causing it to retard the timing, but even swapping out the O2 sensor did nothing to fix it.
 

melsg5

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So we are back to square one, there is nothing to indicate a timing issue.
Two things come to mind dirty fuel injectors and a partially clogged catalytic converter. Do a back pressure test on the converter and check the condition of the injectors.
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