Weird Acceleration - nothing happens, jerks back

[Mx3forever]

Anyone have this happen?

You push gas pedal, no acceleration. Car Chokes.
Then all the sudden it jerks back to acceleration.

Going to stop. RPM dips down and climbs back up.
Sometimes during the dip the car will die.

I thought I had a problem like this licked before by sealing the MAS rubber tube.
I think I have it sealed now but the car is still acting intermittently weird.

Also, it sort of feels that the engine is holding back - like even when it accelerates it isn't accel as much as it should.

[kulluminati777]

When was your last tune up? Maybe its time for new wires, cap and a rotor for the disty? Do 4cyl guys have terrible distys like the V6? Have you seen if its throwing any codes? Maybe the fuel pump is going out?

[RobMinhas]

When was your last tune up? Maybe its time for new wires, cap and a rotor for the disty? Do 4cyl guys have terrible distys like the V6? Have you seen if its throwing any codes? Maybe the fuel pump is going out?

Our distys don't crap out like the v6s but distributors will be distributors. Cap, rotor, plugs, plug wirings and coil are all suspect here.

[Daninski]

Going to stop. RPM dips down and climbs back up.
Sometimes during the dip the car will die.

Could be the neutral safety switch in your trans. I need to replace mine. If I ease the rpms down it's fine but when hot the engine could quit if I just take my foot off the gas at say 2000rpm. I believe Gro Harlem told me about this.

[Demonic1]

Check the ignition coil while you're there too.

[kakarot135]

Mine does it when cold, mine is the distributor, I've just been to lazy to replace it even though I have one sitting in the garage.

[Ryan]

Honestly sounds like a VAF problem to me. Got a spare kicking around to try out?

[dubber084]

Same thing happend to me over the summer.. thought it was the disty, replaced it and it ran fine for about a week then started happening again.. replaced the fuel pump, it ran good for another week then figured out i had to clean my gas tank out. There was some sort of sludge (car had been sitting in a shed for some x amount of years before i got it, so im just assuming a bunch of crap got into the gas tank) just hanging out at the bottom of the tank which would clog up the fuel pump, so cleaned it out and was good to go. Went ahead and replaced the fuel filter and fuel pump yet again after all of that just to have a clean first start again, and now it runs like a champ no problems at all after that.

[mitmaks]

Any codes? Could be as simple as vacuum leak somewhere. I had similar problem turned out to be accordion intake tube had multiple rips in it. I siliconed it and then wrapped it all up with electrical tape, runs like new.

[Josh]

First are you running a 92-93 or a 94+? That can make a difference when it comes to the dizzy. The 94+ had internal coils just like the K series and they have quirky issues just as well, I went through a couple of them.

Through my experience with the RS I would say it could be a one of or a combination of several things.

Vacuum leak
Plugged CAT
Plugs N Wires + dizzy cap and rotor, air filter
Could be a plugged fuel filter, we tend to forget about those.
How old is your O2 sensor?
Spark plugs, when was the last time you changed them? I know when I was boosted I would go through a set about every 20K miles or so. and if they are a little older and if your coil is weak it could cause this.

These are the areas I would start with. Any one of these could cause that issue or a combination of them.

One of the other things it could be is the TPS, usually if you have never messed with it it should be fine, but it could be out of adjustment. Also if you have a VAF 92-93 and you have installed a CAI you want to make sure it is level and not upside down or something.

[Mx3forever]

Thanks for the replies, I haven't had time to check anything on it yet, I was just getting a few ideas of what to start checking.
I've been driving my Miata and had to spend October working on my Cadillac Hearse, but I'm getting ready to put the Miata up for the year and start driving the Mx-3.

I'll try to pull the engine codes today.

[SuperK]

it could be sensors.
I would disconnect tps, see if it's different. if not
disconnect o2 sensor, see if it's different.

Double check your vacuum and intake lines. I know you did work on it, but that would be a good reason to double check your work. something may have gone wrong or have been missed.

[Mx3forever]

I did get around to checking the engine codes, it didn't have any error codes.

The vehicle is running better now. It does die here and there but nothing like before.
What did I do? Nothing. I had Seafoamed the engine, recoated the air pipe with silicon, checked the plugs and wires, replaced the valve cover gasket, cleaned out the PVC and checked for vacuum leaks.

None of this had helped the intermittent dying problem and bouncing neutral RPM.

The problem just started going away on it's own the more I drove it. Maybe it was mad at me for driving the Miata for so long.