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Surging/bucking in all gears at lower RPM. Tune or other?

  • Thread starter Thread starter 281pony
  • Start date Start date Nov 22, 2009

281pony

Active Member
Aug 31, 2003
2,681
2
46
Oly, WA
Nov 22, 2009
#1
  • Nov 22, 2009
  • #1
i have ran codes, nothing besides egr stuff since its deleted. the car has a nasty surge/bucking to it at lower rpm's in all gears. seems to range in the 1300-1700 rpm range.

its mostly at light throttle application/idle. my old fox with a 331 did this, but only in first gear. is this a common issue sorted by dyno tune? it has 24# injectors and a calibrated maf with the a9s ECU.

i've done every bolt-on... h/c/i, tb, maf, exhaust, electric fan, 3g alt, yada yada. its a 5-speed car. so, aside from dyno tuning, is there anything that causes this? i have an sct chip when the time comes.
 

281pony

Active Member
Aug 31, 2003
2,681
2
46
Oly, WA
Nov 22, 2009
#2
  • Nov 22, 2009
  • #2
before anyone asks, i forgot to add.

its a tfs stage 1 camshaft, nothing too aggressive. idle is set at 950 rpm.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Nov 23, 2009
#3
  • Nov 23, 2009
  • #3
The only easy thing I can think to check is to be sure your TPS doesnt have a crap-spot under light load. Look for a nice linear sweep from baseline (~0.60-1.20 Volts) to WOT.

Really watch that lower range where you're having the issues though. I like to use an analog meter (with a needle, not a DMM) so you can really see that there are no dead spots. It's tough to go slow enough to see every hundreth of a volt on a DMM. The needle is easier to watch.
 

281pony

Active Member
Aug 31, 2003
2,681
2
46
Oly, WA
Nov 23, 2009
#4
  • Nov 23, 2009
  • #4
thanks jt.

ill go over it when i get home. if i recall, i did set it properly when i first got the engine in my last fox. it transfered over to this coupe and nothing was touched/adjusted since.
 
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