very tough to solve diagnostic issue

[roughrdr]

If anyone can help with my surging issue on my 2015 ford v10 F53 chassis, your input would be greatly appreciated. Issue is as follows, upon acceleration, some where between 3000, and 3800rpm, the engine surges noticeably. Here is a list of things that are not the problem. Air filter, mass air flow sensor, accelerator pedal sensor or its counter part at the throttle body intake, not the cat converter, not a vacuum leak, or feul filter and the engine does not throw a code to the dash or in the computer. Surprisingly, if I disconnect the battery, similar to unplugging a computer, it stops surging for about 15 to 20 miles and then resumes surging. This surging also happens at freeway speeds, but is not as noticeable unless going up a steep hill. it is also affecting fuel economy. Other than that, the motorhome runs great. Two different rv mechanics were unable to help also. I am searching the internet for wisdom.

[1972VWbus]

First thing you need is a scanner.



Second check and confirm your fuel pressure while under demand.

[TandW]

When you say the engine surges, do you mean to suggest that the coach lurches forward?. I have an idea that you are merely hearing the clutch fan begin to roar. Is that possible?

[TeJay]

What TandW mentioned above is important. When you say it SURGES does it actually lurch forward then resume speed. Can you see the speedometer increase in speed momentarily then resume the previous speed? Does the engine RPM's increase as well. Knowing exactly what is happening is very important.

I doubt you are hearing a fan clutch noise. That does not usually cause any surges. I drove school buses for 10 years. The clutch fan was going on and off all the time and I never once thought of it as a surge/movement. It was just a surging noise but no movement or motion in the engine.

I understand you did give us a list of items as not being the problem. How those were eliminated is also very important. Good diagnostic technicians do understand that every part can be tested and therefore verified as operating correctly as designed by the engineers.

In all my years teaching proper diagnosis to young students some things did occur which always grounded me in reality. Things like, "Well I replaced these 2 or 3 parts and nothing improved."

Many of my students participated in state and national troubleshooting contests more than 25 times over my 35 years. When a student diagnosed a defective part they would ask for a new one and often another bad part was provided. Good students would verify any part they requested.

While it does not happen often sometimes bad parts are in circulation/sold because to save $$$ not all new parts are tested.

The scanner is also important. An engine will surge if it does not have a constant flow of fuel. As 1972VW mentioned do you have a constant flow of fuel therefore correct fuel pressure??? The spark may also be intermittent. Both of these should set a CODE. Since you said there were no CODES my bet is on intermittent fuel starvation.

Contrary to what DETROIT said after 1980 and the introduction of the computers this did not replace the parts changers with greater THINKERS. Finding a diagnostic technician who can think outside the box instead of just changing parts until it's fixed even these days is not an easy task.

An engine that is intermittently loosing it's ability to create power is loosing either spark or fuel. Those two and compression are necessary to create power. The compression is not intermittent. A fuel pressure gauge installed to monitor fuel pressure while the driver is making the engine surge makes good sense.

[avfordguy]

At that rpm, it is likely that the op is climbing a hill and fan clutch is coming on and going off, it's a common issue on ford f53 and e450's as fan clutch starts to engage at about 209 and full lockup at 217 ( approximately).

[donr103]

You need a dedicated fuel pressure gauge and adaptor.. takes 15mins to install but all day to decide where to mount it.. see glowshift.com.. use Ford f250 or f350 same yr as yours..

Now I wonder.. could it be.. the a/c compressor kicking in and out? So.. no one seems to be able to find anything.. next time.. climbing and you have that.. or feel it.. turn hvac controls off.. see if stops.. just guessing here..
Good luck and keep us posted

[tiffy2000]

Has the cat been replaced with perhaps an aftermarket convertor ? If so you may want to buy this adapter ....it has helped several people with surging after an aftermarket CC was installed.

installed a 3mirrors Straight 58MM O2 Sensor Check Engine Light Eliminator Adapter M18x1.5 Mounting Fittings Accessories - Stainless Steel - Walmart.com
You remove your cc sensor, screw this device in and then you cc sensor screws into that

[winnbrave1]

Is there a possibility of a transmission issue?

[sbleiweiss]

Originally Posted by tiffy2000

installed a 3mirrors Straight 58MM O2 Sensor Check Engine Light Eliminator Adapter M18x1.5 Mounting Fittings Accessories - Stainless Steel - Walmart.com
You remove your cc sensor, screw this device in and then you cc sensor screws into that

Shows currently unavailable on Walmart.com.

[TeJay]

Proper diagnosis is a step by step process to check parts and determine if they are actually working correctly. Jumping all around the place from AC clutch noise then Clutch fans etc, etc while simple unless a part is determined to be either good or bad functioning or not nothing gets accomplished.

Is the OP capable of checking some or all of these parts? So far we don't know for sure. He said he checked some parts then took it to 2 shops and they found nothing.

I guess the shops didn't replace any parts? What did they check?? What did they verify about the fuel and or spark? Or did they even check those two items? This is slowly IMHO getting to be a case of one chasing one's tail.

Find a shop that can follow the symptoms. Are you getting a steady supply of fuel???? We still don't know. Has the spark been checked? I still believe if it's an intermittent ignition spark it will cause a CODE to be set. That's fairly simple to check. We still don't know those results.

Our RV seldom causes the cooling fan to engage. In fact it has only come on once in 50,000 miles. I monitor the coolant temps and they are ALWAYS within range no matter hills we climb. No we have not driven over the Rocky Mtn's but we did hit some good hills out East up through NH and that's when the fan came one once.

The coolant clutch fan noise was just that a noise and no surging. One can definitely tell the difference. The same for the AC clutch. In fact I can't ever, (except for cold air) really feel when the AC clutch kicks in and out.

Yes the transmission could be slipping but when that happens the fluid becomes burnt and it smells burnt. Easy enough to check.

[roughrdr]

Originally Posted by TandW

When you say the engine surges, do you mean to suggest that the coach lurches forward?. I have an idea that you are merely hearing the clutch fan begin to roar. Is that possible?

hello all, and thank you for helping out. The surge could be described as if the trans is almost shifting, but not as pronounced as a shift. The crazy thing about it is if I disconnect the battery to clear the computer, it wont do the surging thing until I have driven 20 miles. The second time I disconnected the battery, it went 100 miles before doing the surging thing. As far as fuel pressure, it runs like a raped ape at top speed.

[roughrdr]

Originally Posted by TandW

When you say the engine surges, do you mean to suggest that the coach lurches forward?. I have an idea that you are merely hearing the clutch fan begin to roar. Is that possible?

hello and thank you for your input. As far as the clutch fan, the engine will perform its surge when taking off from a stop, and upon reaching 3000 or so rpm it starts. At this slow speed, it is easy to hear the fan clutch engaging or not engaging. The surge is more pronounced than that also.

[roughrdr]

Originally Posted by TeJay

Proper diagnosis is a step by step process to check parts and determine if they are actually working correctly. Jumping all around the place from AC clutch noise then Clutch fans etc, etc while simple unless a part is determined to be either good or bad functioning or not nothing gets accomplished.

Is the OP capable of checking some or all of these parts? So far we don't know for sure. He said he checked some parts then took it to 2 shops and they found nothing.

I guess the shops didn't replace any parts? What did they check?? What did they verify about the fuel and or spark? Or did they even check those two items? This is slowly IMHO getting to be a case of one chasing one's tail.

Find a shop that can follow the symptoms. Are you getting a steady supply of fuel???? We still don't know. Has the spark been checked? I still believe if it's an intermittent ignition spark it will cause a CODE to be set. That's fairly simple to check. We still don't know those results.

Our RV seldom causes the cooling fan to engage. In fact it has only come on once in 50,000 miles. I monitor the coolant temps and they are ALWAYS within range no matter hills we climb. No we have not driven over the Rocky Mtn's but we did hit some good hills out East up through NH and that's when the fan came one once.

The coolant clutch fan noise was just that a noise and no surging. One can definitely tell the difference. The same for the AC clutch. In fact I can't ever, (except for cold air) really feel when the AC clutch kicks in and out.

Yes the transmission could be slipping but when that happens the fluid becomes burnt and it smells burnt. Easy enough to check.

Your input is greatly appreciated, and I am looking forward to finding my problem. The fuel pressure ,spark and ignition coils were checked. The clue to the answer lies in the fact that when I disconnect the battery, and remove the power to the computer, and then re connect the battery, it stops surging for about 20 miles. The second time I disconnected the battery, and then re connected it, it went 100 miles before surging again, and the fuel economy went back up to 8mpg.

[roughrdr]

Originally Posted by TeJay

What TandW mentioned above is important. When you say it SURGES does it actually lurch forward then resume speed. Can you see the speedometer increase in speed momentarily then resume the previous speed? Does the engine RPM's increase as well. Knowing exactly what is happening is very important.

I doubt you are hearing a fan clutch noise. That does not usually cause any surges. I drove school buses for 10 years. The clutch fan was going on and off all the time and I never once thought of it as a surge/movement. It was just a surging noise but no movement or motion in the engine.

I understand you did give us a list of items as not being the problem. How those were eliminated is also very important. Good diagnostic technicians do understand that every part can be tested and therefore verified as operating correctly as designed by the engineers.

In all my years teaching proper diagnosis to young students some things did occur which always grounded me in reality. Things like, "Well I replaced these 2 or 3 parts and nothing improved."

Many of my students participated in state and national troubleshooting contests more than 25 times over my 35 years. When a student diagnosed a defective part they would ask for a new one and often another bad part was provided. Good students would verify any part they requested.

While it does not happen often sometimes bad parts are in circulation/sold because to save $$$ not all new parts are tested.

The scanner is also important. An engine will surge if it does not have a constant flow of fuel. As 1972VW mentioned do you have a constant flow of fuel therefore correct fuel pressure??? The spark may also be intermittent. Both of these should set a CODE. Since you said there were no CODES my bet is on intermittent fuel starvation.

Contrary to what DETROIT said after 1980 and the introduction of the computers this did not replace the parts changers with greater THINKERS. Finding a diagnostic technician who can think outside the box instead of just changing parts until it's fixed even these days is not an easy task.

An engine that is intermittently loosing it's ability to create power is loosing either spark or fuel. Those two and compression are necessary to create power. The compression is not intermittent. A fuel pressure gauge installed to monitor fuel pressure while the driver is making the engine surge makes good sense.

When it surges, it looses rpm, it does not surge forward?