So this is an issue that only happens when its cold out, and only for a short time after start up (maybe a few stops and starts).

I have a manual, and this bucking only happens when I let the clutch out. the bucking almost feels like im letting the clutch out to fast and the clutch plates are smacking together. This is not the case, since it does not really matter how fast or slow I let out the clutch, or how much gas I give it.
Like I said, this only happens when its cold out and the engine is cold (so every winter morning). My car has 64,000 miles on it and I WAS thinking that it may have something to do with the transmission fluid, I know that it should be changed at 60k (and i am going to change it) but for some reason i dont really think that is the issue, the fluid cannot have that much of an impact on it can it?.
A little more info, the bucking only happens when I go to start for the first 4-5 times from a dead stop, and then it stops. I can get back in my car 5-6 hours later and the engine and temp out can be cold and it will not do the bucking. It only happens the first time driving it in the day.

Any ideas on what this could be, Im stumped.
Thanks

 

Any ideas at all?

 

FWIW, I had a similar, if not the same, thing happen with an old F350 pickup I had. Exactly as you describe and it did this for years and years. Never got worse. Never got better. There was a slight oil leak on that truck and it may be that some of the oil got onto the clutch. I dk if that was the cause. Its just the only thing I knew was potentially wrong with the darn thing. But, like you say, it would go away as soon as things warmed up a bit. And it must not have been too serious because the truck was primarily used to pull a trailer that weighed 14K, which was way beyond the towing capacity for that stock clutch. I kept expecting the clutch to go out and that would have been fine with me because I would have then replaced it with a clutch better suited for what the truck was being used for. But it never did go out and was still working fine when I sold the truck back in 2010. I'm thinking it was probably doing that for at least five years. I think I did mention it once or twice to mechanics and they didn't seem overly concerned and I think one of them suspected that the oil problem had something to do with what was happening. He advised me to try to keep the opening clean because fixing the oil leak would have been very costly and there was no indication that it would get any worse. So that's pretty much what I did. I'd wipe things down with a rag when I changed the oil.

 

My xA did the same and this is what I found out...
During cold operation, engine will run with all sensors bypassed on a preset "map".. this is usually very rich fuel and no timing advance... the bucking is the rich fuel causing close to flooding out performance, this is usually due to old or poor spark plug performance. Changed my spark plugs and have not had problem since, used to have the Bosch Platimum +4 but found out at other forums that platimum should not be used in the 1NZFE, so went with NGK Copper Plus plugs. No problems since and have even noticed smoother idle....Good luck hope this helped.

 

My XA is the same. It usually happens when it's cold and the blue temp light is on. It goes away when fully warmed up (a few blocks). I figured it was due to the car running rich when cold and my Exedy clutch kit.

The OEM exedy clutch uses springs inside the clutch disc while the OEM Toyota disc has what look like rubber bushings. I don't think the springs don't absorb the shock as well as the rubber bushings, so this causes the car to jerk a bit when changing gears. The rubber bushings crack and break eventually, which is why I went with Exedy. Do you have an aftermarket clutch on your car?

 

It a simplier problem than anyone mentioned ... Damp clutch! Your brakes are probably very grabby too when it happens, once the engine heat dries out the clutch it goes away or a few starts, try letting the clutch out just a little while stopped enough to slow the engine a little to warm it up or take off in second gear slipping it a lot and it should dry right up and work fine, otherwise you can rev it to 2500-3000 in first when taking off and ease the clutch slowly to dry it out. This happens to my xb when it rains or is foggy.

 

All of these are good potential points,
Archangel, as far as I know, I don't think that my car has an aftermarket clutch, I am the fourth owner, and the car has a salvaged title, so I'm not sure what the second owner (repair shop) used

 

Hey guys. Stock 04 xB. Same problem here. I've been reading about dirty clutch master cylinder fluid and how it affects hydraulic pressure. I'm trying to locate the danged clutch reservoir. I had my neighbor, a 15 year toyota mechanic, try and look for it but no luck. We were sitting there talking about how the clutch master cylinder reservoir might be the brake master cylinder reservoir. But that's just beer talk... Anyway, once I bleed the reservoir, I'll let ya'll know if that changes anything (if the weather stays cold around here). If that doesn't solve it, I'm looking at a tranny rebuild to give the car an extra 100,000 miles. (94k on it now)



ANYBODY KNOW WHERE THE RESERVOIR IS???

 

The clutch master cylinder and the brake and brake master cylinder reservoir are the same in our car's. It took me a bit to realize it when I first bought my XA. Never seen it before in any other car.

 

In my experience, admittedly with a different vehicle, damp clutch is the best explanation I have heard. I have an automatic xB, so I can't say anything about an xB clutch. But the brakes are often grabby at first this time of year and now I know why. Same thing was happening on my truck when it was bucking and I never made the connection between the two. But one thing I did notice is that I would never get bucking on the truck if I let it warm up before driving. You can't warm the brakes, so they remained grabby presumably until they dried out. Perhaps that is why I never made the connection. I was considering pulling the front wheels and inspecting the brakes the other day even though I already did that last summer and they were fine. It was grabbing that bad. Now I'm certain it is the dampness because it does go away really fast.

 

I had to look under the hood again to see if you were right and by-golly you're right. The brake reservoir is the clutch reservoir. In this case, bleeding the clutch lines is as simple as pumping the clutch as a wrench monkey turns that danged nut on the master cylinder. Procedure: push clutch in, loosen nut, fluid squirts out, tighten nut, let out clutch, repeat. About to try this tomorrow if my neighbor is home. I'll let ya'll know.

 

Yes please do, if that fixes the bucking in the clutch, That would make me happy if it fixes the problem

 

Neighbor just started refinishing the outside of his house. I have to wait for a friend to help me out. If ya'll try the master cylinder bleed, please post results.

 

I tried changing the plugs since a guy I was talking to was saying that that may have something to do with it, so far it seems a little better, but I'm stilling getting the bucking a bit, if anyone does or try's the things they were saying they were going to, keep me posted