bad stutter , lean af reading,,

Kennedy jay

Member
Established Member
Joined
Jun 29, 2018
Messages
32
Location
Louisville ky
so, im running an eaton swap mach 1. vmp tuned, 4 pound pully, stock upper. cobra heads, lethal dual pump kit. 9.5 to 1 comp. factory maf. c and l intake.
lately ive noticed a bad stutter if i hold throttle at,about 1500 rpm, it gets worse under load... really saw it on the dyno.. a/f gauge show lean when this happens. i did notice both fuses on the fuel pump relays were slightly heat damaged. replaced both. both pumps work, but if i remove 1 fuse the rpms of the remaining pump go up.. and the fpr is making a crazy ticking sound...
i replaced the plugs,, checked all the coils.. cleaned the maf, nothing has helped the sputter, lean condition .
any help or opinions appreciated..
 

Kennedy jay

Member
Established Member
Joined
Jun 29, 2018
Messages
32
Location
Louisville ky
fuel pumps are good, maf is reading ok, a/f wideband is jumping from 14.3 to 15.4 or so when its misfiring.. replaced plugs, checked and moved coils around with no change... not throwing a code.. maybe o2s?? anyone?
 

blownstang4.6

Active Member
Established Member
Joined
Nov 8, 2011
Messages
469
Location
Chicago
14.3-15.4 is normal idle/cruising afr. Replace front 02's. If still doing it it's most likely the tune. Why a stock maf?
 

01yellercobra

AKA slo984now
Established Member
Joined
Oct 5, 2005
Messages
21,125
Location
Cali
Rarely both O2's go bad together. Your tuner let the car go with this issue? Or did it start after the tune was done?
 

Kennedy jay

Member
Established Member
Joined
Jun 29, 2018
Messages
32
Location
Louisville ky
after, it was noticed on the dyno about a week ago..would a change in the lower pully from stock to metco 4lb make it run lean? didnt really notice it before. was making a log pull when we noticed it.. it starts being noticeable at about 1500 rpm. setting still. worse under load.
 

Users who are viewing this thread



Top