do 02 sensors affect high rpms

92redsc

Registered User
When my car gets up in high rpms my car starts to hesistate or kind of wimp out. i have to shift into the next gear so it will go to lower rpms and pull. will pull great till around 3500 -4000 and it gives up. my boost gauge reads 14.5 in 2nd and 13 in 3rd with no mods except a removed air scilencer. thas wierd huh? exhaust restrictions? well my intermittent CEL has been staying on longer and longer but still goes off and on alot. the only code is 172, which i know is an 02 sensor so thats why im asking. part throttle performance is great and so is low end performance. i dont know exactly where it should be, considering it hasnt run perfect ever scince i got it, but i know it will kill my moms 94 5 speed v6 mustang. i dont know what the problem is. i know i have a boost leak somewhere cause my vac sits on 15 at idle. but it has tons of power still as long as you in the low end.
 
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Your cats are likely the problem not to mention the resrictions in the system. How many miles have you got ? You would best be served by completly replacing the whole exhaust system. The high levels of boost leave me to believe that your exhaust is futher restricted. Be carefull you are in the blown head gasket zone!!!!!!!!!!!
 
on my car it goes in to open loop at around 4 pounds of boost so if you are over that 02 sensor doesnt affect the performance much
probably cats getting blocked these cars drop off a lot over 4000 rpm unless you get a new cam and good exhaust , my vacuum is around 19 at idle and i never get more than 11 pounds of boost, could be dirty fuel filter or low fuel pressure also
 
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got 96000 miles. um how would i know if its the exhaust? fuel pressure is good and new fuel filter.
 
14lbs of boost on stock exhaust is BAD! I get that now after I did the exhaust and added ASPs and and OD to the SC....good lord!

I think your on the right hunt with the O2 sensors, but it could be a chain of things or just that...however with my luck with my SC its typically a chain of small things...

Anyways fix your problems before you race your mom.

-Tim
 
i think they use a hi temp thermometer to see if converter is a lot hotter in the front than towards the rear ,but with that many miles i would probably just replace them with hi flow cats
 
o2's

try unplugging your o2 sensors and seeing if there's a difference....i know that the only time my car bucked without the passenger side plugged in was under high rpm. my friends sc did the same, replaced both 02's problem solved. (i had my one o2 unplugged because i had all the exhaust off btw....no exhaust restriction at all ;)) oh, and i've noticed that out of two boost gauges i've had on my car, they read differently, just by a little though, especailly on the vacuum side....anyways good luck! :D

derrktor feesh
 
fuel pump

Check the fuel pump, if it is going bad it may not deliverthe full fuel at higher throttle positions and account for the power loss and bucking. Just an idea if the O2 sensors dont do the trick.
 
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