Clutch Bouncing

[JoeSpeed]

I stand by my diagnostic hypothosis; it is a fueling issue at low RPM, high load and cold oil temps (the variable valve timing is too quick to react when the oil is cold and has a higher viscosity, slow to move the cam phasers), the high fuel demand and low RPM relatively speaking is very hard to get metered properly with a DIT only engine. I believe it is not the clutch, but the engine surging due to slightly off fueling and cam position over what it normal. If it goes away under heavier throttle or less load (level or downhill), or when the oil is over 160F, then I would feel very confident in my hypothosis.

I think it is the nature of the beast when cold started.

so let it sit and warm up basically.

Might as well start it up and run back in for coffee or something as it warms up, or just double check your emails and stuff

Sponsored

 

[DesertMike680]

Yeah, I don't think there's anything a service department can do unless it reproduces 100% of the time -- it may just be some odd boost condition where the ECU cuts fuel or purges boost when that combination of variables (whatever it may be) is met. I make sure to note my coolant and oil temp when it happens because I have a feeling this is a somewhat-warm-but-not-fully-optimal oil temp issue only. Air temp plays a crucial role in ECU tune/learning on these engines because temp and air pressure are used to calculate mass airflow -- the RS is the same way.

If the MAP sensors on these engines are easy to get to like they are on the RS, I may just try to clean them off a bit with some MAF sensor cleaner and see if that resolves it. A dirty MAP sensor would cause similar symptoms just much more consistently.

No life or death concerns at the moment, thankfully -- nothing yet that would make me think us 2.3L 7MT folks are in the same boat (or similar) as the 2.7L folks unfortunately are with their valves.

You bring up a good point that someone else did regarding the MAP sensors - I noticed there are a few sensors attached to the intake. Are they all MAP sensors or is it just the one by the intake box?

 

[SPITmadFIRE]

You bring up a good point that someone else did regarding the MAP sensors - I noticed there are a few sensors attached to the intake. Are they all MAP sensors or is it just the one by the intake box?

I'm assuming it's the same as the 2.3L config on my Focus RS but maybe I'll go investigate after work today.

On the RS 2.3L ecoboost there are three intake air sensors total; keep in mind the Tasca links I'm providing are just for reference and will almost definitely not work on the Bronco engine:

Air temp (TEMP) sensor: connected to the intake air inlet just after the air filter; Tasca link
Air Temp AND Mass Airflow Pressure (TMAP) sensor: connected to the intercooler cold (outlet) side, before the throttle body; Tasca link
Mass AIrflow Pressure (MAP) sensor: connected to the intake manifold, after the throttle body; Tasca link (diagram confirmed incorrect with Tasca's support team a few months ago)

The ECU uses cold intake air temp, air temp and pressure prior to throttle body, and pressure after the throttle body to figure out how much boost and gas to call for. If one of these sensors is dirty or faulty, I would expect behavior like we're seeing, but much more consistently. Warming up would probably not help much.

Also, keep in mind with these high-compression, direct-injected motors the PCV system usually has a small amount of oil circulating through it. This oil is what causes intake valve carbon buildup, but it can also cause these sensors to get dirty with oil. I don't think this is the problem we currently have, but can't hurt to keep in mind that after some decent mileage (30,000 - 50,000mi) these sensors will most likely get dirty enough to effect power output. They're fairly inexpensive and easy to replace though.

 

[DesertMike680]

I'm assuming it's the same as the 2.3L config on my Focus RS but maybe I'll go investigate after work today.

On the RS 2.3L ecoboost there are three intake air sensors total; keep in mind the Tasca links I'm providing are just for reference and will almost definitely not work on the Bronco engine:

Air temp (TEMP) sensor: connected to the intake air inlet just after the air filter; Tasca link
Air Temp AND Mass Airflow Pressure (TMAP) sensor: connected to the intercooler cold (outlet) side, before the throttle body; Tasca link
Mass AIrflow Pressure (MAP) sensor: connected to the intake manifold, after the throttle body; Tasca link (diagram confirmed incorrect with Tasca's support team a few months ago)

The ECU uses cold intake air temp, air temp and pressure prior to throttle body, and pressure after the throttle body to figure out how much boost and gas to call for. If one of these sensors is dirty or faulty, I would expect behavior like we're seeing, but much more consistently. Warming up would probably not help much.

Also, keep in mind with these high-compression, direct-injected motors the PCV system usually has a small amount of oil circulating through it. This oil is what causes intake valve carbon buildup, but it can also cause these sensors to get dirty with oil. I don't think this is the problem we currently have, but can't hurt to keep in mind that after some decent mileage (30,000 - 50,000mi) these sensors will most likely get dirty enough to effect power output. They're fairly inexpensive and easy to replace though.

Great info. So, with the issue should we only be focused on the MAP sensor? Maybe I'll grab some cleaner this weekend and spray it down.

 

[SPITmadFIRE]

Great info. So, with the issue should we only be focused on the MAP sensor? Maybe I'll grab some cleaner this weekend and spray it down.

I wouldn't go cleaning them off just yet -- whenever you clean these sensors there's always a risk of damaging them. Cleaning a MAP sensor should be a step you take after you're confident it's an issue, and right before you order new sensors just in case. These sensors are extremely sensitive and incorrectly cleaning them can cause much worse issues.

Also, to be clear -- the above info is only what I know off the top of my head for the RS 2.3L and may not apply to the Bronco 2.3L spec whatsoever. I expect the Bronco also uses MAP sensors (which are much more sensitive than MAF sensors and much easier to damage). I would avoid digging around and touching sensors just yet unless this issue gets significantly worse for you.

 

[SPITmadFIRE]

In a normal world where parts are quick and cheap to get, I'd say fuck it, try cleaning them. However, given it's a new vehicle and also *gestures at world around us* I would avoid trying to fix something that isn't quite broken yet.

 

[DesertMike680]

In a normal world where parts are quick and cheap to get, I'd say fuck it, try cleaning them. However, given it's a new vehicle and also *gestures at world around us* I would avoid trying to fix something that isn't quite broken yet.

Good idea.

 

[Lakelife36]

Thanks @thesocalexplorer for leading me here. I believe I've had the same issue four or five times now in the three weeks and 1600km (1000mi) I've had mine. So far the pattern seems to be engine warmed-up enough to idle down before leaving but not up to full temp yet, level ground, around 2800 RPM, in second gear, and moderate throttle but not into boost. The engine stutters but the tach doesn't seem to wobble, although it's not definitive with the digital display. It does not feel like the clutch is slipping as the engine "dies", not "surges".

 

[Ford Motor Company]

Thanks @thesocalexplorer for leading me here. I believe I've had the same issue four or five times now in the three weeks and 1600km (1000mi) I've had mine. So far the pattern seems to be engine warmed-up enough to idle down before leaving but not up to full temp yet, level ground, around 2800 RPM, in second gear, and moderate throttle but not into boost. The engine stutters but the tach doesn't seem to wobble, although it's not definitive with the digital display. It does not feel like the clutch is slipping as the engine "dies", not "surges".

Hello, Ben! Send us a private message with your VIN and the name and location of your local Ford dealer. I’d be happy to see what I can do to assist with this engine concern. Thanks!

 

[Trilifter7]

I’ve experienced it a few times now and it definetly seems fuel related to me. It happened exactly as described above, 2nd gear and even once in 3rd gear, engine warm after a previous trip and only does it a couple of times on light to moderate throttle then goes away. It feels very similar to hitting a rev limit but at around 2200-2600 rpm.

 

[cyberfalco]

Mine did this the first few weeks but now it is smooth. I attribute it to getting use to a different clutch and being a brand new clutch.

I have almost 2000 miles on it now and it has not done it since those first weeks that I have owned it. I imagine it just needed a little break in period.

 

[Lakelife36]

Hello, Ben! Send us a private message with your VIN and the name and location of your local Ford dealer. I’d be happy to see what I can do to assist with this engine concern. Thanks!

Hello Ford Social Media Team! Thank you for the kind offer, but you've led me down this path before. I can't recommend enough that you take a gander at a member's location before letting them know that you'll help them, when in fact you can't help an assumed 10ish percent of us. Screenshots below for clarity.

 

[mike8675309]

Anyone else with a 2.3 MT notice when the engine/driveline is still cold, at low vehicle speed and around 1.5-2.5k rpm engine speed, sometimes the clutch will 'bounce' in and out of engagement very rapidly (with foot totally off clutch pedal)? Makes mine shake like crazy. At first I thought I was bumping the throttle with my foot from the shaking and magnifying the issue but that's not the case either.
...

Sorry but what you are describing is based on a misunderstanding of how a clutch works in a manual transmission. A clutch on a manual transmission can only engage or disengage from pressure applied by your foot on the clutch pedal. It's still a physical connection, not electronic.

Engine shaking is likely due to misfires in the engine with uneven cylinder pressure causing it to shake. Is it repeatable? If so, take it to the dealer. If not, try and record what is happening with the tach when it happens.

 

[Bronkers]

Hello, Ben! Send us a private message with your VIN and the name and location of your local Ford dealer. I’d be happy to see what I can do to assist with this engine concern. Thanks!

@Ford Motor Company

Not to whine, but what about the Ben that started this thread with the same issue?

 

[Bronkers]

Sorry but what you are describing is based on a misunderstanding of how a clutch works in a manual transmission. A clutch on a manual transmission can only engage or disengage from pressure applied by your foot on the clutch pedal. It's still a physical connection, not electronic.

Engine shaking is likely due to misfires in the engine with uneven cylinder pressure causing it to shake. Is it repeatable? If so, take it to the dealer. If not, try and record what is happening with the tach when it happens.

Thanks Mike and touche...speculation has changed to fuel delivery...

6pgs of folks reporting similar, but hard to document issue here. Whatever it is hopefully it goes away completely on mine, I'm over 17k miles now and am noticing less frequently (but still present).

ECU or some other chipset may be 'learning' or I'm properly breaking it of its bad habit...what do you think?

Sponsored