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"Bucking"

J

Jack_Flash

CEG'er
Joined
Jan 27, 2007
Messages
41
Location
Omaha, NE
I've had this problem with my car wherein it would start "bucking" you might say, whenever I go up hills or accelerate considerably (passing traffic). There really isn't another way for me to describe what it does because it really does feel like the car wants to go but hesitates considerably. The way I try to get around it is to throw it into neutral and just let off the gas a little more when I put it into a higher gear. I've changed my plugs and wires and went through a couple of bottles of fuel injector cleaner. I just bought a bottle of the motorcraft stuff so I'm going to try that. With my luck, though, I will replace everything in there before I actually discover what is wrong. Hence, me posting on here.
 
My car occasionally does the same thing. It feels to me like a fuel system problem. I have a new fuel filter. I'm wondering if it's the fuel pump or dirt in the fuel injection system.
 
Motor and trans?

How old are your plug wires and what kind are they?


I had a set go bad after only 1,000 miles. Autolite Professional Series wires. I had a set of Ford Motorsports wires go bad after only a few thousand miles although they died slowly.
 
Sound like you have a starving engine at high RPM’s. When was the last time you changed your fuel filter? Are all the fuel lines in good shape (bent, pinched)? Was your air filter changed? Vacuum leak may cause this as well, but your engine idle would show that. Are there any CEL codes?
 
i had the same thing in my SVT. I changed the fuel filter but that didnt help. I came to realize that it happens when i have less than half a tank of gas left, which pretty much means its my fuel pump (currently saving money to have it replaced but they are fricken expensive!). So if this is the case with yours i would look at the fuel pump too
 
codypka said:
i had the same thing in my SVT. I changed the fuel filter but that didnt help. I came to realize that it happens when i have less than half a tank of gas left, which pretty much means its my fuel pump (currently saving money to have it replaced but they are fricken expensive!). So if this is the case with yours i would look at the fuel pump too
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Same thing with my car. My air filter, fuel filter, and plugs are new. It happens only at high RPM's, and I'm pretty sure only when I have less than half a tank. I just had my timing belt and starter replaced, and I'm not looking forward to adding a fuel pump to the list.
 
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FWIW -- if you're only getting this symptom when you put your boot deep into the throttle, you may have a mass air flow sensor (MAF) concern. This will not kick a check engine light.

Try squeezing the accelerator gently -- you may able to get the car to accelerate slowly, progressively without hesitation. Now nail the throttle (you can do all of this, say, around 35-40 mph in 3rd gear) -- if the car bucks now, you're probably looking at a MAF failure.

All is not lost, though. Grab a can of $10 mass air sensor cleaner at the auto parts store, pull the air filter out, and remove the entire MAF housing. Spray a good solid snort full of the cleaner at the MAF wire (don't be shy), being very careful not to let anything else touch it. Let it dry, throw it back in, button up the filter, and fire the car up (it may stumble a touch, but will start and idle smoothly). Take 'er for a rip -- see if this cures your problem.

Occasionally, the wire gets gummed up -- thus, the computer can't tell how much air is entering through the filter, and it can't meter the right amount of fuel. Often, the failure is on the starvation side -- too little, not too much fuel, hence the buck, or blip, or spot where nothing happens under throttle. The MAF is constantly reporting back to the computer, so you should not have to bother with resetting -- the table should update just fine in open loop strategy.

Hope this cures it -- take care.
 
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LauraSVT said:
FWIW -- if you're only getting this symptom when you put your boot deep into the throttle, you may have a mass air flow sensor (MAF) concern...
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You couldn't be more awesome. An MAF problem makes sense in my situation, because the mechanic didn't reassemble my MAF properly after changing my timing belt. He said he fixed it, but I suspect it still needs attention. I'll try the MAF cleaner.
 
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LauraSVT said:
FWIW -- if you're only getting this symptom when you put your boot deep into the throttle, you may have a mass air flow sensor (MAF) concern. This will not kick a check engine light.

Try squeezing the accelerator gently -- you may able to get the car to accelerate slowly, progressively without hesitation. Now nail the throttle (you can do all of this, say, around 35-40 mph in 3rd gear) -- if the car bucks now, you're probably looking at a MAF failure.

All is not lost, though. Grab a can of $10 mass air sensor cleaner at the auto parts store, pull the air filter out, and remove the entire MAF housing. Spray a good solid snort full of the cleaner at the MAF wire (don't be shy), being very careful not to let anything else touch it. Let it dry, throw it back in, button up the filter, and fire the car up (it may stumble a touch, but will start and idle smoothly). Take 'er for a rip -- see if this cures your problem.

Occasionally, the wire gets gummed up -- thus, the computer can't tell how much air is entering through the filter, and it can't meter the right amount of fuel. Often, the failure is on the starvation side -- too little, not too much fuel, hence the buck, or blip, or spot where nothing happens under throttle. The MAF is constantly reporting back to the computer, so you should not have to bother with resetting -- the table should update just fine in open loop strategy.

Hope this cures it -- take care.
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If you could perhaps provide a visual of the MAF wire that would be awesome too. I learn by visuals lol
 
Jack_Flash said:
If you could perhaps provide a visual of the MAF wire that would be awesome too. I learn by visuals lol
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Ok, here it is -- no sweat.
maf2.jpg

This is actually out of a Mustang, but since its from the Motorcraft family, it looks no different, fundamentally. The harness plugs in on top, and the flange facing you in the picture bolts in between the throttle body and the air filter via those four holes visible here. When cleaning the MAF, focus on the marked section (A) -- the wire is little, but important. As mentioned before, be sure not to touch it. Once you've let the cleaner evaporate, bolt everything back together, plug the MAF harness back in, fire it up, and you're ready to go. Obvious tip -- make sure that the MAF is facing the right way when you put it back in -- the harness should plug in on the side closest to the front of the car. Direction of air flow is marked on the housing if any questions arise.
 
Carbon tracking

Carbon tracking

My experience with 2-3000 rpm bucking is one of the sparkplugs has developed a carbon track (looks like a crack) on the porcelain insulator. Mine was plug #2 center cylinder firewall side. I had this problem with new plugs/wires. Have to make sure the socket wrench and plug boots are clean, and use silicone ignition grease in the plug boots. I gapped plugs a little tighter than spec, .050.
 
I have the same problem with the Taurus. Likes to buck right around 60km/h. If I put the boot to the floor it goes away. I had changed the fuel filter and the air filter, but I keep forgetting to look at the plugs/wires.
 
yea i cleaned out my maf sensor and it didnt fix it. actually my car bucks with about half a tank as well. i'm new to the car so i'm wondering if this is something that happens to a car with 53k. just looking for some help
 
SVT_TEE said:
yea i cleaned out my maf sensor and it didnt fix it. actually my car bucks with about half a tank as well. i'm new to the car so i'm wondering if this is something that happens to a car with 53k. just looking for some help
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If the MAF is really far gone -- you may need to just replace it. I had one go in a Taurus SHO years ago where the failure was sufficient to screw up when the secondaries would open, creating a bog. Tousley Ford in Minnesota should be able to hit you with a low price.

You getting any stalling with this? I am assuming that the car stays running -- correct me if I'm wrong.
 
LauraSVT said:
If the MAF is really far gone -- you may need to just replace it. I had one go in a Taurus SHO years ago where the failure was sufficient to screw up when the secondaries would open, creating a bog. Tousley Ford in Minnesota should be able to hit you with a low price.

You getting any stalling with this? I am assuming that the car stays running -- correct me if I'm wrong.
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Would it stall out if it was the MAF? Funny enough the gf came home and said that morning I posted that the car wanted to stall out twice when she started it.
 
loggerbomb said:
Would it stall out if it was the MAF? Funny enough the gf came home and said that morning I posted that the car wanted to stall out twice when she started it.
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Well, your girlfriend's help may have narrowed things down. The MAF would not cause a stall. However, the throttle position sensor would. It could also cause a bog or a dead spot under throttle.
 
LauraSVT said:
Well, your girlfriend's help may have narrowed things down. The MAF would not cause a stall. However, the throttle position sensor would. It could also cause a bog or a dead spot under throttle.
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Would it be similar to some bucking/hesitation, cause thats how it started. Would do it at the same spot all the time after a week or so, right around 60KPH.
 
loggerbomb said:
Would it be similar to some bucking/hesitation, cause thats how it started. Would do it at the same spot all the time after a week or so, right around 60KPH.
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Sounds like it to me. The information that the TPS is sending to the computer could be faulty within a certain range, causing your bucking / bog, etc. around a particular speed. It may get worse, and just crap out whenever it sees fit. You might check it out before it gets that bad :cool:
 
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