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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

random drop in RPM at idle

  • Thread starter Thread starter Dizzy_ax
  • Start date Start date Jun 20, 2009
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HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Aug 15, 2009
#21
  • Aug 15, 2009
  • #21
You are clearing the codes after you retrieve them, right?

Put your meter on the TPS signal and ensure that it goes from ~1 V to ~5 V, with no breaks in the reading.
 

Dizzy_ax

Member
Mar 26, 2008
93
1
8
Troutdale Oregon
Aug 16, 2009
#22
  • Aug 16, 2009
  • #22
last time i did the checked it only went up to 4.35ish?

I cleared the codes when i reset the TPS. the check engine light pops on from 10 seconds to about one minute. depending on if im just cruising highway speeds or driving around town. The digital meter im using goes up pretty smooth and back down smooth.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Aug 16, 2009
#23
  • Aug 16, 2009
  • #23
You need to check it at every last bit of movement you can. It's a lot easier with an analog meter if you have one (it's easier to see the needle dip). I try to literally see every hundreth on a digital meter.

Did you ever get a TPS code for low voltage after you disconnected the TPS? If you did not, that indicates there's a wiring issue (short to VREF) or a bad TPS (the wiper is shorting to VREF). More testing is needed (if you want to get into this, we need to know how the 123 and other codes were generated [Memory codes, etc]).
 
S

Stevejr

Member
Dec 17, 2008
63
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6
Humboldt Tn
Aug 16, 2009
#24
  • Aug 16, 2009
  • #24
I maybe way off here but my car was doin the same thing. I cleaned the maf and it was cured.
 

Dizzy_ax

Member
Mar 26, 2008
93
1
8
Troutdale Oregon
Jun 5, 2011
#25
  • Jun 5, 2011
  • #25
Time to close the thread, i finally figured this one out! I have BBK headers and i guess its common once you start getting into the high heat mods they crack around the collectors. So im getting cold air passed my O2 sensor and the car reacts according to the reading leaning and then dumping once it gets too hot. Just in case anyone else runs into this i do believe i bought the cheaper BBK shorties and the guy at the All ford proformence said he has seen this before. might be something to look into if you have had this problem (I replaced everything sensor wise because of this and it ends up being the header )
 

Dizzy_ax

Member
Mar 26, 2008
93
1
8
Troutdale Oregon
Jun 5, 2011
#26
  • Jun 5, 2011
  • #26
Woops forgot to thank everyone in the thread with the ideas (This problem happened right after the S/C was installed. Also had tons of popping on deceleration (Sounded like a rally car which in turn got me a nice careless driving ticket ) Long story but im passed all that now
 
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