excessive engine vibration

[tjg8675]

Hi All,
Well this ones got me stumped...
I'm getting excessive engine vibration at idle in park/neutral and throughout the rev range while driving and no koeo or koer codes except the pass code.
I thought it might be the crankshaft position sensor but unfortunately I do not have one, which would've been the easy fix.
This was made confusing for me because all the parts stores list a crankshaft position sensor for the 95 bronco 5.8l.
Instead from what I have read I have a pip sensor inside the distributor...I'm thinking about replacing the distributor but not sure if this is the right direction without asking here first.
Also would anybody know if i need a steel gear or a cast iron gear? or any info on how to find this information hopefully without having to pull the distributor...
Any input would be greatly appreciated
thx

 

[miesk5]

Yo TJG,
003.htm#extract_24
"Vibration Conditions
Vibration, technically, is a high-frequency trembling, shaking or grounding condition, felt or heard, that is constant or variable in level and occurs during a portion of the total operating speed range. The types of vibrations that can be felt in the vehicle can be divided into three groups:

• vibrations of various unbalanced rotating parts of the vehicle
• body and frame vibrations excited by powertrain, wind or road inputs
• tip-in moans or resonance vibrations from stressed engine or exhaust system mounts or driveline flexing modes

For engine or accessory vibration, all speeds, refer to Pinpoint Test D in the Diagnosis and Testing portion of this section.
●For high-speed shake/vibration, 80 km/h (50 mph) and up:

• Refer to Pinpoint Test A in the Diagnosis and Testing portion of this section and to Section 04-04 for tire conditions contributing to shake/vibration.
• Refer to hub and rotor runout checks in Section 06-00.

For tip-in moan, refer to Symptom Charts in the Diagnosis and Testing portion of this section. If the symptom still exists, refer to Pinpoint Test B in the Diagnosis and Testing portion of this section or the engine assembly in Section 03-01A, Section 03-01B, Section 03-01C or Section 03-01D.

For brake shudder, refer to Section 06-00.
Vehicle vibrations can also be subdivided into those that occur at low speeds and those that are most noticeable at higher speeds. Since the dividing line between low and higher speed vibrations is not clear, there will be vibrations that overlap the two ranges.

Typical Low-Speed Vibrations (Less Than 72 km/h [45 mph])

• exhaust vibration
• engine harshness
• driveline vibration due to improper driveline angles
• power steering pump disturbances
• air conditioner compressor or drive belt (8620) vibrations
• take-off shudder (driveline problems)
• brake roughness or harshness
• driveline roughness
• driveline slip-yoke or rear axle universal joint ****** (4851), automatic or manual transmission clutch slippage

Typical High-Speed Vibrations (Above 72 km/h [45 mph])

• rear axle universal joint ****** runout or imbalance
• driveshaft (4602) imbalance
• excessive tire-wheel and drum assembly imbalance
• tire roughness due to high non-uniformity (force variation) or out-of-balance condition
• rear axle pinion gear pitch line runout
• excessive tire and wheel runout
• worn suspension components
• front end accessory vibrations
• exhaust vibration (greatly reduced in exhaust systems de-coupled by a flexible coupling and mounted with blade and block hangers)

Harshness Conditions

Harshness is the term commonly used to describe the ride quality concern of the vehicle. A hard ride or harshness is usually caused by the tires or suspension system, namely:

• overinflated, wrong size or wrong type tire installed on the vehicle
• suspension not sufficiently lubricated
• worn suspension components
• suspension components installed with preload on pivot point, bearings and bushings
• vehicles equipped with tires not specified by the manufacturer (different brand tires often give different ride qualities to the vehicle)
• bent or bound-up shock absorbers
• heavy-duty components installed on vehicle

Other harshness conditions that affect ride quality may be summarized as follows:

• Vehicle bounce — the vertical motion of a vehicle on its suspension system, front and rear in phase, a low frequency "float" or an intermediate frequency "kick."
• Vehicle pitch — the out-of-phase vertical motion of the front and rear of the vehicle. A flat ride would be considered the opposite of a pitch ride.
• Vehicle roll — the side-to-side rotation of the vehicle body about the front and rear axles

 

[miesk5]

Yo,You have a 95?
1989-91 Bronco (Non-Roller Cam)
Gray Push Start TFI, Distributor Mounted, Iron Gear

1992-93 Bronco (Non-Roller Cam)
Gray Push Start TFI, Remote Mounted, Iron Gear

1994-95 Bronco (Roller Cam)
Black CCD TFI, Remote Mounted, Steel Gear

 

[tjg8675]

Yes 95

I forgot to add its running rich, I pulled the o² sensor and it was black soot coated instead of the chalky white

Also still vibrates with belt removed

 

[miesk5]

Yo T,
Suggest you use Typical High-Speed Vibrations (Above 72 km/h [45 mph])
Rule out as much as you can test each component cited. Then we can draw in other members here for their inspections, testing, etc.

• rear axle universal joint ****** runout or imbalance
• driveshaft (4602) imbalance
• excessive tire-wheel and drum assembly imbalance
• tire roughness due to high non-uniformity (force variation) or out-of-balance condition
• rear axle pinion gear pitch line runout
• excessive tire and wheel runout
• worn suspension components
• front end accessory vibrations
• exhaust vibration (greatly reduced in exhaust systems de-coupled by a flexible coupling and mounted with blade and block hangers)

 

[Motech]

Yes 95

I forgot to add its running rich, I pulled the o² sensor and it was black soot coated instead of the chalky white

Also still vibrates with belt removed

It sounds to me from your first post that you may have a dead misfire. And ⁷while a soot covered oxygen sensor in and of itself is not conclusive, it could indicate either an injector is hanging open causing a misfire and a rich running condition from too much fuel flow, or an ignition injector not opening at all (more likely) causing that cylinder to pump nothing but air. The O2 sensor would return a constant lean, value from all that air, and the computer would compensate by enriching too far.

Or I could be totally off base, and it could be an imbalance issue, like an engine mount or a broken harmonic balancer.

Either way, I would want to find out if I have a dead miss first.

A cylinder contribution test is needed.

A good, old school way to do that is take a pick, or make one with a long skinny screwdriver by grinding the tip to a point. Then clip a jumper wire to the shank and clip the other end to the engine for ground.

With the engine idling, and you holding the handle and not the metal shank, you can pierce each distributor cap boot of the plug wire until it contacts the metal terminal inside. That will short that plug wire and cause it not to fire that cylinder, literally creating a misfire.

You'll end up going around all of them a few times to get a feel for it, and if you do have a cylinder misfiring, there will be no change in the engine when you pierce the correlating plug wire. Ideally, each each time you pierce one, it should have the same effect as all the others do in dropping the idle down and creating a miss. The one that does not is your culprit.

If you identify a misfiring cylinder that way, pull the spark plug and have a look at it. Dry and white is consistent with no fuel delivery. Moist but otherwise decent could indicate too much fuel flow at that cylinder. Moist and gunked up with carbon would be a little more consistent with compression loss.

Either way, when you identify the miss wearing cylinder, you'll want to measure compression on that cylinder anyway.

 

[tjg8675]

It sounds to me from your first post that you may have a dead misfire. And ⁷while a soot covered oxygen sensor in and of itself is not conclusive, it could indicate either an injector is hanging open causing a misfire and a rich running condition from too much fuel flow, or an ignition injector not opening at all (more likely) causing that cylinder to pump nothing but air. The O2 sensor would return a constant lean, value from all that air, and the computer would compensate by enriching too far.

Or I could be totally off base, and it could be an imbalance issue, like an engine mount or a broken harmonic balancer.

Either way, I would want to find out if I have a dead miss first.

A cylinder contribution test is needed.

A good, old school way to do that is take a pick, or make one with a long skinny screwdriver by grinding the tip to a point. Then clip a jumper wire to the shank and clip the other end to the engine for ground.

With the engine idling, and you holding the handle and not the metal shank, you can pierce each distributor cap boot of the plug wire until it contacts the metal terminal inside. That will short that plug wire and cause it not to fire that cylinder, literally creating a misfire.

You'll end up going around all of them a few times to get a feel for it, and if you do have a cylinder misfiring, there will be no change in the engine when you pierce the correlating plug wire. Ideally, each each time you pierce one, it should have the same effect as all the others do in dropping the idle down and creating a miss. The one that does not is your culprit.

If you identify a misfiring cylinder that way, pull the spark plug and have a look at it. Dry and white is consistent with no fuel delivery. Moist but otherwise decent could indicate too much fuel flow at that cylinder. Moist and gunked up with carbon would be a little more consistent with compression loss.

Either way, when you identify the miss wearing cylinder, you'll want to measure compression on that cylinder anyway.

Hi Motech,
Thanks for the reply
I checked all the plugs today and all looked normal, none were dry and white.
Going to get it checked out by an actual mechanic tomorrow as I dont have the time or energy to futz with it at the moment
hopefully nothing requiring major surgery, will update this thread when I know more

 

[Tiha]

I am in the same thoughts as missfire.

You said the plugs look good and no codes. At least yet. So I would be thinking of things not monitored. Like plugged/restricted fuel injector. Low cylinder compression.
Maybe test fuel pressure to eliminate that.

 

[paul rondelli]

If your PIP is going ...... then your RPM gauge should be doing some funky movements. Since the PIP provides RPM data to the ecm ... and directly to the RPM gauge it should show deviations on the gauge.

Do you have a slight miss at wide open throttle? .... or if she is hard to start ... keep an eye on the RPM gauge to see if it jumps.

I had to replace my dizzy on the 1996 Bronco about a year ago. She has run awesome since. No more misses.