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

BUCKING BELOW 1500 RPM

  • Thread starter Thread starter godstangit
  • Start date Start date May 3, 2006
G

godstangit

New Member
Dec 21, 2002
187
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Illinois
May 3, 2006
#1
  • May 3, 2006
  • #1
What causes the bucking/jerking below say 1500 rpms, it almost feels like a miss, could it be a lean condition?
 

The Green GT

No 13 year olds are safe around me.
10 Year Member
Jan 8, 2006
1,269
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Louisiana
May 3, 2006
#2
  • May 3, 2006
  • #2
I narrowed my similar problem down to a fuel pump relay. I pulled codes and got a fuel pump relay fault. I think it has something to do with the huge plug by the colant resevoir tank.
If you find a fix let me know.
 
G

godstangit

New Member
Dec 21, 2002
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May 3, 2006
#3
  • May 3, 2006
  • #3
I didnt pull any codes,that would indicate fuel circuit or anything,
 

MysteryMachine

Active Member
Jun 21, 2003
1,835
2
39
Parkesburg, PA
May 3, 2006
#4
  • May 3, 2006
  • #4
anybody think of too low of RPM?
 

blksn955.o

Founding Member
Mar 15, 2002
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st.louis mo 314
May 3, 2006
#5
  • May 3, 2006
  • #5
from a tune aspect, the maf may be the fault as well. Low rpm bucking/load is a symp. of a maftransfer that is off.
 
G

godstangit

New Member
Dec 21, 2002
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May 3, 2006
#6
  • May 3, 2006
  • #6
Brilliant Just that it recently started though, Im gonna check the timing and clean the MAF and see if it helps.
 

1TallMF

New Member
Apr 17, 2006
955
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Montreal
May 3, 2006
#7
  • May 3, 2006
  • #7
I had that same problem a couple months ago. It turned out to be two of the plug wire boots had melted down to the core and I guess were arcing on the headers. Changed the wires, and the low-rpm miss went away instantly. Damn those infernal equal-length headers
 

MysteryMachine

Active Member
Jun 21, 2003
1,835
2
39
Parkesburg, PA
May 3, 2006
#8
  • May 3, 2006
  • #8
1TallMF said:
I had that same problem a couple months ago. It turned out to be two of the plug wire boots had melted down to the core and I guess were arcing on the headers. Changed the wires, and the low-rpm miss went away instantly. Damn those infernal equal-length headers
Click to expand...
you can give them to me
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
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May 4, 2006
#9
  • May 4, 2006
  • #9
Does it feel different at WOT versus light throttle application?
 

The Green GT

No 13 year olds are safe around me.
10 Year Member
Jan 8, 2006
1,269
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99
Louisiana
May 4, 2006
#10
  • May 4, 2006
  • #10
HISSIN50 said:
Does it feel different at WOT versus light throttle application?
Click to expand...
On my car is it the same as always on WT. But every once in a while it will buck once.
 

SM0k3

Founding Member
Jun 3, 2001
580
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La Palma, California
May 4, 2006
#11
  • May 4, 2006
  • #11
my car bucks slightly during steady light throttle, kinda annoying on the freeway.
 
Y

yellowclone

New Member
Mar 16, 2006
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0
May 4, 2006
#12
  • May 4, 2006
  • #12
1TallMF said:
I had that same problem a couple months ago. It turned out to be two of the plug wire boots had melted down to the core and I guess were arcing on the headers. Changed the wires, and the low-rpm miss went away instantly. Damn those infernal equal-length headers
Click to expand...
Alittle off topic, but I just put those thermal boots on the two plug wire that were rubbing on the header tubes. I haven't had a problem in two and a half years yet.
 

1TallMF

New Member
Apr 17, 2006
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0
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May 4, 2006
#13
  • May 4, 2006
  • #13
yellowclone said:
Alittle off topic, but I just put those thermal boots on the two plug wire that were rubbing on the header tubes. I haven't had a problem in two and a half years yet.
Click to expand...

I am going to do the exact same thing to the new wires before they melt too. I'm procrastinating though, they are harder to find than I had thought they would be, there's not too many performance shops around here, and none of the regular parts stores have them. I'll order a set tomorrow maybe.
 
G

godstangit

New Member
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May 5, 2006
#14
  • May 5, 2006
  • #14
HISSIN50 said:
Does it feel different at WOT versus light throttle application?
Click to expand...
Well I notice it when under a slight load at low RPM but wide open it hauls pretty good with no apparent problem, cleaned the MAF, checked for vac. leaks,and re-set the idle 750-800, and no codes, BUT I did notice a ticking sound coming from the PCV valve, and was wondering if that is normal cause Ive never heard them make noise before, theyre supposed to rattle around when you check them but this was too wierd
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
May 5, 2006
#15
  • May 5, 2006
  • #15
There is a spring inside the PCV valve - it might have gotten weak on you. That said, I've heard GM PCV valves make a tickin noise (sounded like lifter tick).
 
G

godstangit

New Member
Dec 21, 2002
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May 5, 2006
#16
  • May 5, 2006
  • #16
HISSIN50 said:
There is a spring inside the PCV valve - it might have gotten weak on you. That said, I've heard GM PCV valves make a tickin noise (sounded like lifter tick).
Click to expand...
Yeah it sounds like a lifter or rocker arm, just wondering if its getting stuck , or not working right all the time and causing it to run bad, think Ill put a new one on and see.
 
G

godstangit

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May 5, 2006
#17
  • May 5, 2006
  • #17
Ive been told all cammed 5.0s have this problem and changing the fuel trim and doing a MAF voltage transfer/table via a Tweecer or other tuning device would be the solution.
 

final5-0

Mustang Master
Apr 6, 2003
6,817
12
79
DFW Texas
May 5, 2006
#18
  • May 5, 2006
  • #18
godstangit said:
Ive been told all cammed 5.0s have this problem and changing the fuel trim and doing a MAF voltage transfer/table via a Tweecer or other tuning device would be the solution.
Click to expand...

Well

When I first read your original post and glanced down at your provided sig, which is much appreciated btw

I said to myself ... Its cause he's got all those Hot Rod parts

I saw later in the thread where Greg mentioned some things about the tune and you seemed to dismiss the info with your "its never done it before" reply.

However with this post, it seems to tell a different story

If it has indeed never done it before, it could be something mechanical, or something like an electrical connection, v leak, etc.

If it has always done it ... then ...............

I can say most Stangs with mods like yours experience drivability issues such as you talk about here

I experienced that kinda stuff and more with my combo

I was able to get the demons exercised with my Tweecer

I did stuff like Greg talked about above
and
Lowering spark values in mid load driving conditions helps with bucking a good bit as well

Grady
 

The Green GT

No 13 year olds are safe around me.
10 Year Member
Jan 8, 2006
1,269
19
99
Louisiana
May 5, 2006
#19
  • May 5, 2006
  • #19
final5-0 said:
I said to myself ... Its cause he's got all those Hot Rod parts
Click to expand...
Thas why Im not ganna tell my dad and grandfahter if I do anything to my car. lol. As soon as something goes wrong, thats all Ill hear.
 
G

godstangit

New Member
Dec 21, 2002
187
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Illinois
May 5, 2006
#20
  • May 5, 2006
  • #20
FINAL 5-0: I stand corrected I shouldve said "it hasnt done it this bad before" It really ran alot smoother before, now it feels as though the trans is gonna fall out of it unless I down shift and even then it feels like a miss untill wide open, checked it for vac leaks today with some carb cleaner and nothing,I might lower the timing to 12 or so and change the PCV valve thats ticking and see what it does.
 
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