Bucking at cruising highway speeds

Tony8470

Registered User
It's been doing it intermittently. What I concluded cause it.

Cruising and climbing a gradual hill. Get to the other side of the hill and coast down when I get to the bottom and press the gas to maintain highway speed it will buck and stutter. Not always, some trips, not at all.

I think it has something to do with the engine getting warmer from the ascent then cooling down during descent. If I take it out of gear and let the car idle while going downhill (to cool off further) it is alot worse. Only on the highway though! ~~~!

The car doesnt get near overheating though. I have a 180 tstat but a MP FMIC as well.
 
Does it start happening when you start going into boost? My car would buck under boost but was fine while in vacuum. Duane Nettles had the same thing happening with his car. We both found a bad spark plug with ceramic material cracked.
 
There is a problem with warm starts sometimes. I'm sure above anything it needs a tune. I could try cam sensor. I've never had the upshift light come on though.
 
How severe is the bucking and stuttering? I've had that happen on both my old 89 Ranger and my 93 SC. In both cases is was due to the o/2 sensor leads having rubbed through and being grounded intermittently as the cable swings, or when driving through water.

This would cause severe bucking, my guess being the EEC-IV was very unhappy with it's o2 wires being shorted to ground.
 
I think I'll go ahead and replace that. If I read right all you do it take the old one out and replace it. Nothing needs messed with?
 
I think I'll go ahead and replace that. If I read right all you do it take the old one out and replace it. Nothing needs messed with?
Are you talking about the crank sensor? If you're going to replace that then you're going to need to make a note of where exactly the old one was bolted on at. You also need to make sure there's a tad bit of space between the sensor and the crank. If I remember right I think I used a spark plug gapper to set my gap. Stuck it on my SHO and the thing fired right up and ran good ever since.
 
I just had, and fixed the same problem. Mine would misfire/buck hard when at partial trottle motsly on highway. It ended up being a bad ground. I hooked a jumper cable up from the neg on battery to the frame and no more misfires. give it a shot. try battery to car then engine to frame.. easy place to start
 
Back
Top