Stuck throttle cable

[ryanprins13]

Huh, maybe your manifold gasket decided to disappear... your throttle plate/valve isnt stuck part way open?

If your aftermarket fpr was sending too much fuel would that increase rpm without air?
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[TominMO]

1. Huh, maybe your manifold gasket decided to disappear...

2. your throttle plate/valve isnt stuck part way open?

3. If your aftermarket fpr was sending too much fuel would that increase rpm without air?

1. I'll be doing a thorough check on Saturday, when it warms up and I have more time. I can't see a gasket leak causing it to rev consistently to 5K tho.

2. Nope. Very strong return spring too.

3. Given a normal amount of airflow, I think I would just have a really rich situation, but I don't see how that would make it rev so high. Gotta be something like Arty says. Everything looks fine from up top, so I have to get under it for any more checking.

It's like it's under heavy turbo boost as soon as you turn the key on, and stays that way until you shut it off. So yeah, big hole somewhere.

[firebush357]

Yeah, it is going to have to be a rather large hole to be able to pull in enough air to sustain 5K. Maybe try putting a heavy duty Ziplock bag over the Throttle body with a clamp or some rubber bands so that No air can get through the throttle plate and then crank the car. If it turns on and revs up it should force more air through the hole and it might be easier to find.

[TominMO]

Gonna get on this in the afternoon; can't wait until tmw to see what's going on. Last weekend I made the Grand Tour of my three local JYs, and one had a gen2 323 there with motor intact (that yard has its own Mazda section, along with all other major brands). So I can go grab another intake if needed (which it probably is).

[TominMO]

Well, poop.

Went out to try to find the source of the huge air leak. Got under the car, used a strong flashlight to check out the underside of the intake mani. Nothing, it all looked fine. Looked all over the topside, rechecked all hoses, everything looks fine. Did the whole process two or three times. I even took a camera out there for a "Well there's your problem" pic.

Tmw I will try starting it with the air completely blocked off. I don't think it will start. I am beginning to think there is no air leak, but have no idea why it is acting this way.

I better start coming up with excuses.
"No officer, I wasn't trying to evade you when I blew through those thee stop signs and went past the grade school at 75 mph. My car only runs at WOT."

Or I could just sell it to Charlie as a dedicated track car....:highly_amused:

Edit: the throttle plate is a tiny bit open, even with no cable connected. But I believe that is normal, otherwise it wouldn't idle at all due to no air intake. Is that correct? Or should the throttle plate be completely closed when the engine is off?

[TominMO]

After a little more research, I'm thinking stuck throttle plate. So tmw I'll try cleaning it with some carb cleaner.

[WmWatt]

When the original problem occured I would open the hood I would look at the end of the throttle cable and try unstucking the throttle by working it manually. You may have had a isolatged random event.

[TominMO]

When the original problem occured I would open the hood I would look at the end of the throttle cable and try unstucking the throttle by working it manually. You may have had a isolated random event.

At this point, I don't even have the throttle cable connected, and am having this happen.

[ryanprins13]

Run it and take a garbage bag and hold it in all different spots, maybe it will plug off and you can find the leak.
Or spray starting fluid around and when it hits the rev limiter or explodes then you found it.
Probably start with some intake cleaner on the throttle plate though. Or see if the idle screw is too high somehow.

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[tooldude]

Try plugging the brake booster. Don't let plastic get pulled in with all that suction. Rubber bands probably won't hold it. I wouldn't risk using plastic.

[TominMO]

Fixed it. :-)

Bought some MAF cleaner and TB cleaner. Cleaned the MAF. When I went to clean the TB, I noticed a couple small pieces of hard plastic in there, holding the plate open! They had come off my cone air filter, when I drilled into the chrome end piece to mount a bracket. Under the end piece was the actual plastic cap. This is what had a couple pieces broken off it. So I cleaned out the TB, reassembled everything, and it runs fine.

[FestYboy]

Good to hear.

[WmWatt]

Another automotive mystery solved.