Engine bucking???

[fairlane347]

My car has a bucking type feeling ONLY between 40-60 mph in OD. All my COP seem fine, plugs are good. I checked my TPS and its working porperly. Its only when the car is at part throtle or costing, under load its fine. Any Ideas????????????

[Zack]

Did you have the car tuned after the new engine was installed?

[merc]

Did you have your kit balanced prior to assembly.:confused:

All 4.6 modular motors are internally balanced. The 3.75" stroker crank is considered a 5.0L (301cid with .020 over bore) and requires balancing. Most machine shops and engine builders have dynamic balancing as an option. But to Mustang & Fords, dynamic balancing and extreme attention to detail are mandatory steps in an engine build. Dynamic balancing is crucial to engine smoothness and survival because vibration (any vibration, no matter how small) kills. It shakes things to pieces. Not balancing an engine is foolish, courting disaster at worst and shortening engine life at best.

When you dynamic balance an engine, you balance the crankshaft (just as you would tires and wheels) for smooth operation. Then, you balance connecting rods and pistons to match the crankshaft balance. Do this every time you build an engine. If you have this problem a tune will not fix the issue.

[Zack]

I second what merc said.
If you bought a kit and 'bolted it in' this could be your problem.

But if you did not have the car tuned after the 5.0, go this route first.

[fairlane347]

Did you have the car tuned after the new engine was installed?

DUH yes I had it tuned.

[fairlane347]

Did you have your kit balanced prior to assembly.:confused:

All 4.6 modular motors are internally balanced. The 3.75" stroker crank is considered a 5.0L (301cid with .020 over bore) and requires balancing. Most machine shops and engine builders have dynamic balancing as an option. But to Mustang & Fords, dynamic balancing and extreme attention to detail are mandatory steps in an engine build. Dynamic balancing is crucial to engine smoothness and survival because vibration (any vibration, no matter how small) kills. It shakes things to pieces. Not balancing an engine is foolish, courting disaster at worst and shortening engine life at best.

When you dynamic balance an engine, you balance the crankshaft (just as you would tires and wheels) for smooth operation. Then, you balance connecting rods and pistons to match the crankshaft balance. Do this every time you build an engine. If you have this problem a tune will not fix the issue.

Yes it was properly balanced. I reseached the hell out of everything befor I bought it, I have built plenty of engines so I know what I am doing. Its not a vibration, like I said the egnine surges alittle but has good power. I

[Zack]

Are you running the same plug gap with and without the Nitrous?

[Frank Androski]

am having the same problem since we as country went to 10 percent
ethanol!. i believe it has something to do with the o2 sensor . just a guess. we use to use ethanol to pas emission inspections years ago when we did not have time for a thirty to forty min. warm up and it worked.
will run out this tank and fill with gas i have stored for my generator and
post again. or you could run almost empty and try some aviation fuel?.
good luck by the way i`v lost two M.P.G. since the change....

[merc]

Yes it was properly balanced. I reseached the hell out of everything befor I bought it, I have built plenty of engines so I know what I am doing. Its not a vibration, like I said the egnine surges alittle but has good power. I

If you are ruling out the mechanical aspect then let's look at spark. Also give Darrin a call concerning the Over Drive, he might have some insight. What are the RPM's when the engine begins to buck? FYI engines vibrate and transmissions buck.

[fairlane347]

am having the same problem since we as country went to 10 percent
ethanol!. i believe it has something to do with the o2 sensor . just a guess. we use to use ethanol to pas emission inspections years ago when we did not have time for a thirty to forty min. warm up and it worked.
will run out this tank and fill with gas i have stored for my generator and
post again. or you could run almost empty and try some aviation fuel?.
good luck by the way i`v lost two M.P.G. since the change....

I have been running the 10% E and it has not changed.

[fairlane347]

If you are ruling out the mechanical aspect then let's look at spark. Also give Darrin a call concerning the Over Drive, he might have some insight. What are the RPM's when the engine begins to buck? FYI engines vibrate and transmissions buck.

i don't remember at what rpm I will have to look.

[Dragcity]

I had an 89 Escort GT that bucked like hell at 35 to 55 MPH. It had a bunch of sensors replaced over time. I think the MAF, TPS and O2's.... It was long drawn out process to solve, but eventually we got it.

Sounds like a metering issue to me, and don't disagree it is in the engine...

[merc]

i don't remember at what rpm I will have to look.

You might have a good engine tuner but the art to getting to the Marauder to sing is in the transmission. Low RPM's in high gear will cause your bucking problem. Since our transmissions are electronic controlled then it would be in the tune. What's your rear gear ratio?

[Frank Androski]

I have been running the 10% E and it has not changed.
"also have a new hyundai 6000 mi. was getting 27 mpg. hwy , now down to 24. same driver, different gas . the cumberland farms station was the last here to implement --.-- citrus county fl.
if your not affected ,i am glad for you , but if you know somethink i don`t
i hope you will share ..
the hyundai runs like it was on rails , but it`s the marauder that lays the track, got to love it ,. thanks

[Aren Jay]

Who went to 10% e?

[imorb1994]

Who went to 10% e?
Gas stations are selling gas that contains 10% ethanol.

[Frank Androski]

this is now the law of the land!!!!
great bunch we have steering this ship of state.
i now have to pay for two more gal. to go the same distance. per tank.

i will not sell the Marauder !, but i may have to live in it

[fairlane347]

This thread is NOT about 10% E gasoline. The gas is unrelated to my issue.

[Zack]

Stupid me for not thinking of this sooner.

Provided your EGR is still on, it may need adjustments in the software to adjust for the added cubic inches.
Have your tuner turn it off completely and see if the problem persists.

[omarauder]

Maybe the IAC (Idle Air Control) is faulty or plugged. I think it is used at the speeds you mention whenever your foot is off the gas, or just off idle, and your coasting along.

[fairlane347]

Maybe the IAC (Idle Air Control) is faulty or plugged. I think it is used at the speeds you mention whenever your foot is off the gas, or just off idle, and your coasting along.

I will look into that.

[RF Overlord]

I thought the IAC only controlled the idle speed when your foot is off the gas. I didn't know it could make the engine run poorly as well.

[merc]

I thought the IAC only controlled the idle speed when your foot is off the gas. I didn't know it could make the engine run poorly as well.

You are right. You can block both valleys and the car will run, it might idle poorly, but when you apply gas you should not have a problem. This is easy to test.

[Yo Vic]

My car has a bucking type feeling ONLY between 40-60 mph in OD. All my COP seem fine, plugs are good. I checked my TPS and its working porperly. Its only when the car is at part throtle or costing, under load its fine. Any Ideas????????????

I had the same symptom, turned out to be the #7 coil.

[JimmyXR7]

[quote=Frank Androski;635373]"also have a new hyundai 6000 mi. was getting 27 mpg. hwy , now down to 24. same driver, different gas . the cumberland farms station was the last here to implement --.-- citrus county fl.
if your not affected ,i am glad for you , but if you know somethink i don`t
i hope you will share ..


Same here, My Marauder started to surge recently at about 25 MPH in the morning, light throttle, on city streets.
They (EPA, gov) want you to drive the car to warm it up quicker, so after the MM stablizes in 10 to 15 seconds I have been driving off, (for the last 3+ years I have owned my MM). About 30 seconds later, the MM now starts to surge. By the time I am to the freeway, the problem is gone, so I will have to increase my warm-up time in the driveway unless someone can tell me what it is besides the gas.
My MM has 54,000 miles on it with the precentage heavy on Freeway miles.
Jim

[fairlane347]

I had the same symptom, turned out to be the #7 coil.

I am not sure if mine is a bad coil? Does yours only do it in OD? Does it do it when the car is cold? Mine does it more so when the car is hotter. This is driving me nuts.

[Frank Androski]

Who went to 10% e?

The nation did as of may 26th it became law

[Zack]

I am not sure if mine is a bad coil? Does yours only do it in OD? Does it do it when the car is cold? Mine does it more so when the car is hotter. This is driving me nuts.

Did you look into the egr yet?

(I posted about it above)

[fairlane347]

Did you look into the egr yet?

(I posted about it above)

No not yet. I was told I should take off the vaccum lines for the EGR plug them and drive it to see if it changes. I might do it at lunch today. Could the O2 sensors make the car act up??? I DON'T get any check engine light though? This is pissing me off, that I can't find the problem.

[Zack]

No not yet. I was told I should take off the vaccum lines for the EGR plug them and drive it to see if it changes. I might do it at lunch today. Could the O2 sensors make the car act up??? I DON'T get any check engine light though? This is pissing me off, that I can't find the problem.

O2 Sensors will get Lazy before they go out, yes.
I doubt this is the problem because the tuner would have cought it when datalogging.

[merc]

O2 Sensors will get Lazy before they go out, yes.
I doubt this is the problem because the tuner would have cought it when datalogging.

I just replaced two lazy O2 Sensors.

[Zack]

I just replaced two lazy O2 Sensors.

Bet you dont pay $20 a piece for Ford OEM Sensors like I do :banana2:

[fairlane347]

I pluged my vaccum for the EGR and drove it. I only drove it a short distance but it did seem a bit better. It does not matter now I just talked to my tuner and he said the EGR is turned off. So its not the EGR valve.

[fairlane347]

Well my next step is to have my friend that works at a Ford dealer do a cop stress test and check all the other vitals to see if anything comes up.

[DTRMiguel]

I am having this same issue here just at 75-85. Light throttle. Would it be smart to change the plugs first?

[Go2GuyFL]

When was the last time you've changed the transmission fluid?

Owning a CV, GM, and a Thunderbird over these past 12 years all with the 4.6L V8 has taught me to have the transmission flushed every 70K to 90K miles. The electronic transmissions run hotter than most and will develope a chatter between 40 MPH to 50 MPH and then again at 70 MPH to 80 MPH.

It is now a standard service at the "stealer" to power flush the transmission for about $99. They'll include an additive which helps slow down the breakdown of the fluid from the heat.

If it continues after the service, then you might be looking at needing a new torque converter.

[jdenning002]

Was it the COPS or the O2 sensors???

[RF Overlord]

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[jdenning002]

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