Absurb Jerking/Bucking Motion

[Luken10]

Ever since I bought my P5 it has a tendency to jerk back and forth at low RPMs, especially in 1st and 2nd gear. (I have a manual) For example, the car will idle fine at about 1100 RPMs, but the moment I touch the gas it will jerk the car backwards. I suppose it is the same motion as being rear ended. If I keep it at a constant RPM and let off the gas the engine braking is very pronounced and will throw me forward in the car. Similar to hitting an object head on. It becomes incredibly hard to drive the car smoothly in the lower gears.

Sometimes I with an extremely slight and steady increase in throttle I can drive slowly and be close to being smooth. Other times, still while being incredibly smooth, the car will do both motions and the car will jerk back and forth repeatedly. I would compare this to someone learning to drive a manual and the car is bucking back and forth. (Definitely not driver error, I am confident in my standard transmission abilities.)

I am sure a lot of people will say "motor mounts!" Previously I found that my front and passenger side mounts were shot. Kind of got jipped from a forum member on here, so the passenger side mount is torn, but has an insert. The front mount is a solid AWR. Drivers side is confirmed to be in like new condition. Rear mount looks to be okay, but it is kind of a pain to inspect, so it is not 100%.

Another thing to note is after my car has been driven for a while, especially in stop and go traffic, the clutch begins to "chatter" when engaging from a stop. It is a violent shake which rocks the car back and forth rapidly. In order to avoid it I have to feather the clutch at a higher RPM. Usually at about 2000. The clutch pedal also seems to have a slight "crunch" to it and less feel when these conditions arise. I have installed a SS clutch line and bled the fluid correctly, but did not solve this problem.

I am not sure if all my symptoms are completely different problems, or maybe the are amplifying each other. Just to specify the first bucking I am specifying only involves adjusting the throttle. The clutch is fully engaged when this happens. The second bucking or jerking is when the clutch is about half way engaged.

Thanks in advanced for the help everyone!

 

[pcb]

The P5 is apparently geared really low which leads to tricky clutching on this car. It's especially noticeable in stop and go traffic.

Check out this link about a 'crunchy' clutch. :

http://www.mazdas247.com/forum/show...ift-gears-when-stuck-in-rush-hour-PLEASE-HELP

 

[LtStiles]

Check for any leaks between your MAF and throttle body. Pay close attention to the ribbed area. Any air that gets into the engine without going through the MAF will give you issues similar to what you are describing.

 

[Luken10]

The P5 is apparently geared really low which leads to tricky clutching on this car. It's especially noticeable in stop and go traffic.

Check out this link about a 'crunchy' clutch. :

http://www.mazdas247.com/forum/show...ift-gears-when-stuck-in-rush-hour-PLEASE-HELP

I can't believe they would put a car into production that is so difficult to drive smoothly. I am pretty positive the extent of mine is much worse than factory, as it can be quite ridiculous sometimes. I actually have posted in and have previously read the thread you posted. Thanks for digging that out though! Just from reading on here and other sites I think my clutch problems have to do with the flywheel. I am just basing this off of other peoples' experiences, and honestly don't have a clue from my own knowledge. My clutch doesn't slip, so I am thinking the clutch itself is fine.

Check for any leaks between your MAF and throttle body. Pay close attention to the ribbed area. Any air that gets into the engine without going through the MAF will give you issues similar to what you are describing.

Definitely not something I have looked for. I have a K&N intake so I know the tubing is fine. Will definitely take a look at where everything connects. How big of a gap would make a noticeable effect? When I inspect it should I be looking just to make sure everything is snug, or can extremely tiny holes/gaps be an issue? Also, is there a way to troubleshoot without just doing a visual check? I know you can use carb cleaner to check for vacuum leaks, is there something similar for this?

 

[pcb]

Just from reading on here and other sites I think my clutch problems have to do with the flywheel.

I could see that happening,... if you have any 'hot spots' on your flywheel, it could make it hard to engage smoothly. I remember putting a new clutch in a car years ago and they wouldn't warranty the new clutch unless the flywheel was resurfaced first.

I know you can use carb cleaner to check for vacuum leaks, is there something similar for this?

I used a propane torch with a two foot piece of surgical tubing stuck onto the end of it. Open up the valve (without lighting it of course) and surf around the engine with the tube. The engine rpm will increase when you feed it into a leak. You can really pinpoint a leak this way. Try to keep the propane canister close to vertical or you could spew liquid propane out of the tubing. (not a good thing)

 

[pcb]

I noticed too that when I did a seafoam treatment, the idle smoothed right out and it was a lot easier to gently give it gas. That made my clutching smoother and easier.

I just replaced a dragging front caliper and that even made a difference in my ability to get it rolling smoothly from a stop. I just bled the clutch cylinder as well and I couldn't believe how much difference that made. I don't get how flushing out a few tablespoons of old fluid can make the clutch softer smoother and more sensitive. (maybe somebody could explain this to me). I thought I screwed something up because the clutch was so much softer but I tried it and it worked and felt great.

You could have a bunch of little things going on and all working together to turn your car into a carnival ride.

 

[ap123]

Your idle is quite high, just an observation. it should be at 700 +/- 100rpm i believe, it says on the sticker under the hood.

My car is the same under engine braking in first and second, it feels just like hitting the actual brakes.

Right before changing the stock clutch i was having issues when i got stuck in traffic too. Or when i did a hard pull. i think the stock pressure plate gets over heated or something. The clutch would get less predictable and hard to drive. The pedal feel would also change it would feel soft then hard all of a sudden then back to normal. But i never had issues engaging or disengaging like the guy in the link.

Right now i have clutch master fx400 six puck with a stock fly wheel and its actually pretty easy to drive, the clutch is very predictable and i have no problem driving smooth, but dont get me wrong it catchs super hard.

 

[pcb]

Ever since I bought my P5 it has a tendency to jerk back and forth at low RPMs, especially in 1st and 2nd gear. (I have a manual) For example, the car will idle fine at about 1100 RPMs, but the moment I touch the gas it will jerk the car backwards. I suppose it is the same motion as being rear ended. If I keep it at a constant RPM and let off the gas the engine braking is very pronounced and will throw me forward in the car. Similar to hitting an object head on. It becomes incredibly hard to drive the car smoothly in the lower gears.

I just reread this and that is definitely normal for this car. I just noticed too that you're from California so you're not just talking 'stop and go' but traffic jam type crap where you're creeping along at three miles an hour.

I'm lucky in that I've only had to deal with that annoying crap a few times but when I do, I'm in the habit of not even trying to give it gas or let it off. I just put in the clutch and start over in whatever gear I'm hopefully going to need.

My car will definitely do the bunny hop in first or second gear anywhere around the 1,100 RPM mark, if I move the gas pedal at all,.. up or down.

Try increasing your following distance to smooth out your speed and practice not being pissed off when somebody slips into the space you've created.

It must really suck to be in daily traffic jams.

(you could try to lube up your throttle linkage and try a seafoam treatment to smooth out your idle but this car has it's limits at three miles per hour)

 

[LtStiles]

Definitely not something I have looked for. I have a K&N intake so I know the tubing is fine. Will definitely take a look at where everything connects. How big of a gap would make a noticeable effect? When I inspect it should I be looking just to make sure everything is snug, or can extremely tiny holes/gaps be an issue? Also, is there a way to troubleshoot without just doing a visual check? I know you can use carb cleaner to check for vacuum leaks, is there something similar for this?

Any unmetered air getting into your engine is bad. You are looking for loose connections, but mainly you are looking at the ribs on the tube connecting the MAF and your throttle body. In the valleys of the ribs you need to see if any are split open. Taking the tube off makes this job a lot easier.

 

[pcb]

He doesn't have this:

He's got this:

I think I know what he's talking about now. He wasn't "idling" at 1,100 RPM,... he was "cruising" at 1,100 RPM in first or second gear and tried to give it gas or let it off.

It shouldn't matter what clutch he's got (it isn't being used) or if there is a vac leak (I had a huge crack and couldn't tell) but that is a damn hard thing to do on this car.

Go ahead and try it,... put your car in first gear,... bring it up to 1,100 RPM,... hold that speed for a few seconds,... then try to give it gas or let it off smoothly.

You are ZEN with your P5 if you can do that without spilling your coffee.

 

[Luken10]

Do you think one of those cans of propane used with small camping stoves would do the trick? Also how dangerous is that? Common sense tells me I am going to blow my eyebrows off, guess I am not understanding how to do it in a sensible manner.

Driving in traffic down here can absolutely be a pain in the rear. AP123, the idling, or as PCB better put it, cruising speed is right around 1000 RPM I believe. Was an educated guess off of experience, might be off a couple hundred. I definitely do leave a larger than needed gap in traffic in order to not have to use the clutch as often. The problem is I can be smoother by feathering/engaging the clutch rather than just staying at a cruising idle speed and then giving it gas. By accelerating a decent amount I can be smooth, but tiny throttle changes on their own will potentially turn my car into a metal headbanging concert.

I think the clutch shuddering because of the flywheel, or at least something out of my control as it only happens after a decent amount of clutch usage. I can't afford the 1000 dollar job right now. I would probably be fine if I could comfortably keep a cruising speed at idle, thus removing my need to use the clutch so often. I think I will try and get a video of how jerky it is sometimes. Maybe I will fit some sort of hanging pendulum to show how much movement is going on.

I will probably try replacing the rear motor mount with the solid AWR mount I have. I am thinking that will kind of balance things out and keep movement to a minimum. Wish me luck on that one! Because you pretty much need to take off the intake manifold to get to the mount, it seems that would be a great time to check everything is up to snuff. I have heard it can be tricky getting the intake manifold back on correctly. My engine has been rock solid as far as misfires, or codes being thrown. How easy is it to screw up that job?

One last thing for this post! Could more people who have read this thread tell their experience while trying to be smooth during slow or heavy traffic conditions? Would be good to know some sort of baseline of how the car is truly supposed to be.

 

[pcb]

Do you think one of those cans of propane used with small camping stoves would do the trick? Also how dangerous is that? Common sense tells me I am going to blow my eyebrows off, guess I am not understanding how to do it in a sensible manner.

That can should work fine,... but you need to put the tube (I guess any flexible tube) on the end of the torch head like this:
I don't think it's any more dangerous than using carb cleaner or anything else,... it all has to be flammable to work. You do it outside of course with the hood up so you don't get any buildup of propane.

By accelerating a decent amount I can be smooth, but tiny throttle changes on their own will potentially turn my car into a metal headbanging concert.

That's the part I think is normal for this car.

I think the clutch shuddering because of the flywheel, or at least something out of my control as it only happens after a decent amount of clutch usage. I can't afford the 1000 dollar job right now. I would probably be fine if I could comfortably keep a cruising speed at idle, thus removing my need to use the clutch so often. I think I will try and get a video of how jerky it is sometimes. Maybe I will fit some sort of hanging pendulum to show how much movement is going on.

Your car may definitely be worse than normal. The more your car bucks, the looser your mounts get, then the worse the bucking gets. I rarely have to work the clutch that much nor deal with California type heat as often.