I have a 00 Protege 1.8L that shifts hard but only after a warm start. I drive into work every morning just fine. Then inevitably I'll have to drive out an hour or two later. The car shifts extremely hard from 1st to 2nd.. The car will jolt, sometimes the wheels will screech.. Once in a while the "O/D Off light" will flash, other times it does not. Usually the problem resolves itself after a short amount of time.

I'm a bit worried that I could be furthering damage by continuing to drive it like this. At the same time, I'm not particularly interested in pursuing this at a shop or dealer as long as it's getting me to and from work and remains intermittent.

Is this limited to a transmission problem only? Obviously its a transmission problem, but generally speaking my idle sucks and can act funky at times. Otherwise the car is pretty tuned up with new plugs, wires, air filter, clean MAF, clean throttle body. Possible vacuum leak noise that I haven't been able to locate. Never tested fuel pressure. Trans has fluid but the car has 155k so I'm reluctant to do anything with it.

Any ideas on why this is happening only after a warm start?

 

This could actually be more of a engine driveability thing than a tranny thing. the tranny reacts to what the engine does and if the engine does funny things the tranny may do so too.
I used to have a Ford Windstar and in the winter time while the engine was still warming up it was bucking when stopped at a red light while the shifter was in D. the cause was a vacuum leak. It made the idle go up and down which cause the whole vehicle to buck.

If you have a vacuum leak that you actually hear than it is likely a busted air intake hose, the thing between the air filter and the throttle body. Take it off and bend it to look for cracks in the ribbed section. If any cracks show clean that hing on the outside and wrap it with good quality duct tape.

If it is not that, look for a missing or disconnected hose.

 

Thanks this is kind of what I wanted to hear. The air intake hose was replaced less than a year ago and is in good shape. I tried the carb cleaner trick for vacuum leaks but am not extremely familiar with the entire system. I tried spraying around the air hose connections, throttle body, intake manifold, fuel injectors. The only vacuum lines I'm able to identify are the brake booster, PCV and the one coming out of the valve cover. Are there diagrams of this available for the 1.8l?

It sounds like it could be coming from the throttle body/gasket or under it. EGR?

 

I think you pretty much identified the vacuum hoses. On the 1.5 L you also have a hose to the EGR Boost Sensor. It sits on the firewall, passenger side and the hose goes down behind the intake manifold where it attaches to a nipple. I suppose the 1.8 is similar. Pull the hose off and poke into the nipple to remove any crud.
Then there is a vacuum hose to the fuel pressure regulator. pull it off completely and see if there is any gunk in it. If it smells like fuel you may have a busted membrane in the fuel pressure regulator.
the EGR valve and passages are definitely worth checking, even if you don't have a trouble code. This video shows how and gives you some more ideas:
Did you ever get the tranny serviced?

 

Thanks for the response. I bought the car a year or so ago at 138k and it now has 156k. I have not touched the transmission and my research has led me to believe that it's not a great idea to mess with the fluid at this point. I am interested in taking a look at the EGR system since it seems like it might be a common problem with this breed of car. How would you rate the difficulty of getting the intake manifold off?

I've seen DIY smoke machines on youtube for vacuum leaks that I might try (or the cigar trick)..

I would also be interested in knowing if the low idle could be related to fuel delivery? I've gathered so far that the car doesn't have a test port for fuel pressure? I'd be weary of cutting into fuel lines.

How do I rule out Idle Air Control issues? Often when I'm doing around 40mph and I coast and let off the gas pedal -- the rpms will drop down to 800-900 then always predictably surge back up to a max of 1500 before dropping down again. When its going back up to 1500 it makes a noticeable difference in the coasting speed of the car before slowing back down to idle.

No CEL. (I have intermittent P0421 that isn't on at the moment -- the more highway driving, the less it comes up)

 

You have pretty much done the tune up with wires, plugs, filters, cleaning the MAF sensor and cleaning the throttle body.
You don't need to take the intake manifold off unless you know for sure that the lower intake manifold gasket is leaking.
As next step I suggest you take off the throttle body again and the EGR valve. Give the EGR valve a good cleaning. Also spray the B 12 chemtool into the EGR passages of the intake manifold. You don't have to remove it to do that. The EGR ports are at the 6 and 12 o'clock positions at the mouth of the intake manifold.
Have you checked the nipple for the EGR boost sensor vacuum hose?
The idle air controller sits at the throttle body. you probably had it cleaned together with the throttle body. But you can do it once more with throttle body cleaner. Any dirt in there could slow the controller's action and that could be responsible for the almost dying and jumpy idle.
Don't use anything else but dedicated throttle body cleaner on the throttle body.

The Haynes manual suggest to check the fuel pressure at the fuel filter. BTW i think it would be a good idea to get the Haynes manual.

You may try an easy way to clean your catalytic converter with Lacquer Thinner (NOT PAINT THINNER!!!) here is how:


Also refer to this tread:
https://www.mazdaforum.com/forum/maz...%E9g%E9-31136/