bucking car over 1500rpm

Rodoggx · 07-24-2006, 09:13 PM

Hello,

Some background: My 1990 5.0 has been sitting in the garage unran for a really long time ~8 months. Recently I installed some flowmasters, bought a new tire for it, and charged the battery (trying to get it up and running).

Over the weekend I got it all buttoned up and took it for a spin. It ran smoothly- no problems. Two days later and now it bucks like crazy while driving. Its almost like the engine dies for a hot second. It'll stutter and loose 500 rpms but when the revs come back it bucks and when driving on the highway the bucking can be quite violent. It most often dies/bucks over 1500 rpm (under load) but sometimes it'll stutter at idle (not to often tho). No noises. The engine just seems to die, lose the 500 rpm, and then fires again. Doesn't seem to happen at any consistent time interval either.

I was HOPING it was something as simple as bad gas or moisture in the tank. So I filled it up and put some STP gas treatment. So far no change (25 miles later).

So guys, any suggestions?

Thanks,
Roland

Coupe50h · 07-25-2006, 06:23 PM

5 speed I assume?

Could be a number of things, i actually been having the same thing ever since i went with another maf sensor.
could be the clutch, could be a vaccuum leak.
I think you may need to clean your pin connector, and also your maf sensor, if you dont know how, run a search so you can clean it properly with brake cleaner.
I wouldnt replace a whole lot of tuneup parts until that is done.

Vamp89 · 07-25-2006, 06:25 PM

mine kept doing that till I swapped my distributer.

LX5liter · 08-03-2006, 02:18 PM

You might ant to check your fuel pressure as well. I've seen weak pumps act the same way.

07-24-2006, 09:13 PM	#1
Rodoggx Registered Member Join Date: Oct 2002 Location: VA. Posts: 71	bucking car over 1500rpm Hello, Some background: My 1990 5.0 has been sitting in the garage unran for a really long time ~8 months. Recently I installed some flowmasters, bought a new tire for it, and charged the battery (trying to get it up and running). Over the weekend I got it all buttoned up and took it for a spin. It ran smoothly- no problems. Two days later and now it bucks like crazy while driving. Its almost like the engine dies for a hot second. It'll stutter and loose 500 rpms but when the revs come back it bucks and when driving on the highway the bucking can be quite violent. It most often dies/bucks over 1500 rpm (under load) but sometimes it'll stutter at idle (not to often tho). No noises. The engine just seems to die, lose the 500 rpm, and then fires again. Doesn't seem to happen at any consistent time interval either. I was HOPING it was something as simple as bad gas or moisture in the tank. So I filled it up and put some STP gas treatment. So far no change (25 miles later). So guys, any suggestions? Thanks, Roland __________________ 1990 Mustang LX 5.0 - All STOCK!!!! Wha?!!! Stock???.... no money for mods..

07-25-2006, 06:23 PM	#2
Coupe50h Registered Member Join Date: Aug 2002 Location: SanAntonio, Tx Posts: 957	Re: bucking car over 1500rpm 5 speed I assume? Could be a number of things, i actually been having the same thing ever since i went with another maf sensor. could be the clutch, could be a vaccuum leak. I think you may need to clean your pin connector, and also your maf sensor, if you dont know how, run a search so you can clean it properly with brake cleaner. I wouldnt replace a whole lot of tuneup parts until that is done. __________________ X-Texas highway patrol ssp 1990 coupe - exploder Gt-40 iron heads, Explorer intake, 19 lber's. E-cam. crane 1.7 rollers. 190fp. 75mm maf. 65mm tb, tubular subframe connectors, mac cai, Asp crank pulley, T-5, king cobra clutch, flowtech 1-5/8 unequals, mac X-pipe Frpp driveshaft, lakewood Lca's. race weight 3,160 12.69 @ 107.35, 1.71 60' 26x8.5 drag's 3.90 gear 13.20 @ 106.91 - 235/60/15 firestones 2.3 60' 3.27 gear

07-25-2006, 06:25 PM	#3
Vamp89 Registered Member Join Date: Mar 2006 Location: Fort Wayne, Indiana Posts: 49	Re: bucking car over 1500rpm mine kept doing that till I swapped my distributer. __________________

08-03-2006, 02:18 PM	#4
LX5liter dude5l Join Date: May 2001 Location: Grande Prairie, Alberta, Canada Posts: 603	Re: bucking car over 1500rpm You might ant to check your fuel pressure as well. I've seen weak pumps act the same way. __________________ Good luck! Brad R. 1992 L.X. 5.0 coupe MODS: A few little bolt ons New Best time ...11.60 @ 128 mph @ 2000+ ft altitude. Rice Haters Club member #39 Users rides #2542

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