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Dodge Repair/acceleration stumbling, oxygen sensor stuck

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Question
Hello Kevin,
I don't know if this is allowed, I already ran these questions by Roland but here goes. I have a
1995 Dakota 5.2 V8 5-speed with some modest mods. It's been a great truck with 135,000 on
it. The mods have brought mileage up from 14 when new to 20 but have now dropped to 16
with a closed loop acceleration stumble unless rpm is above 2200-2400 depending on which
gear it's in, above this rpm it accelerates perfect, also in open loop there are no symptoms.
I'm suspecting the oxygen sensor but I can't get it out. It's in a set of Mopar Doug Thorley
headers and I'm afraid of stripping the threads. I've been on it with muscle and a 1/2" breaker
bar with 14" cheater pipe, no luck, WD40 hasn't helped. There are no dash light error codes
nor any picked up by my Genisys EVO. I do have Bosch Platinum plugs in it and I read some
engines don't like those but I've been running them for years having switched from Splitfire
plugs whose gap increases 1/1000 every thousand miles. I read the intake manifold on these
engines has a plate inside that is prone to gasket leaks but I see no pooling oil as the said
tell tale sign of that looking in there just normal wetness from the PVC system, plus this is
only a problem in closed loop. Any ideas about the reduced mileage and acceleration stumble ?
The stumble is only if 50% or more throttle is applied, else not there. Also any special tips on
how to get out stubborn oxygen sensors like mine ? I've done a lot of web searching without
coming up with much. I did put anti seize on it when I installed the headers at about 30,000
miles. I know to pull plugs only on cold engines so I am hesitant to try heat. I bought
some penetrating "Freeze Off" oil that is supposed to shock bolts down to minus 40 cracking
their threads enough to get the oil in but not sure this would be good way to go either. Thanks
for any help. Roland was a good guy but could only think of a leaking EGR valve with no oxygen
sensor removal experience. The truck doesn't have any idling issues, just this closed loop low
rpm half to full throttle stumble and a stuck oxygen sensor. Thank you for your time and any
kind of help you might offer. I've been a wrench jocky since high school. I'm 64 now and it's
only occasionally I get stuck on something anymore that I need outside help with. Thank you
again for your time, I know time is money, Jim S.

Answer
Hi Jim,
Kevin "punted" your question to the "pool", of which I am the only other person. If you have looked at the oxygen sensor readings and unless they are out of range, then I wonder why there is no fault code. You know the wires for those sensors are fragile so you might want to verify carefully that the wires are OK. The other thing that comes to mind is that the TPS might have some discontinuity in its variable resistance slider. So check that out with a volt-ohmmeter when the engine is warmed up fully. Also, have you cleaned out the throat of the throttle body lately?
Best of luck with this and do let me know what solves it.
Roland

Dodge Repair

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Roland Finston

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Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question or asleep overnight so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top expert" from 2010-2015 here at AllExperts, and have answered 20,000+ questions.

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Five decades as a 'do-it-yourselfer' on domestic and imported cars

Organizations
Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Education/Credentials
Degrees in Physics/bruised knuckles.

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014, and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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