I feel stupid asking this because I checked everything but here it goes........

Just installed a MPx 60mm TB on my car, pulled the old one off put the new one on maybe 30mins tops? had no issues, installed was a breeze until i went to start the car.....The car immediately revved up to 7k before i turned it off. I double checked everything and all was good. I even went as far as pulling it off again, putting it all back togather and reset the computer. Just sitting in the car looking at my gauges, the RPM is already pegged at 8k without any keys in the ignition. With keys in the ignition the check engine light flashes on and off. I figured ok, the computer thinks i am flooring it or has a bad communication with the sensors on the TB. Well i pulled off the connectors and it was still reading 8k. At this point i am stumped, and asking for help. I did not bore the manifold yet in case your wondering i was just checking to make sure this would go ok at first. Glad i am checking. Could it be a bad vacuum hose leak? O2 sensor? Working fine with the old TB before i pulled it off, why the problems now?

Any help would be great! Thanks

 

check to make sure the TB sensor is installed correctly, and make sure your TB plate is closed.

 

You are using a gasket right? And yea check vacuums also.

 

plate is closed, i remember redoing the sensors which at first i thought it was too but i will check again, and yes i am using a gasket

 

Are you trying to say that the tach is stuck at 8k even thought the car is off???

If so you have to take the gauge cluster out. and flip it upside down so the needle goes to the middle and then tilt it toward the 0RPM mark and then flip it back around...

What mods do you have to warrent using a 60mm TB by the way...

 

K, not trying to start an argument or thread jack, as this directly relates to expressos 60mm throttle body and what warrants his using it. This is directly out of the mouth of my father, a man who has both a masters and doctorate in physics, and as a teenager who was out on his own at 15 with no parents, built a 11 second chevy vega on money earned at a turkey slaughter house at the age of 20.

In an engine/intake manifold set up that uses a carb, the volumetric effiecientcy rule applies, because as the size increases, the airflow increases and therefore the fuel must to compensate, since it is being mixed in the carburator itself.

In a fuel injected car where the throttle body leads straight to the ports, this also applies, because with a smaller throttle body, the air is going to move faster and therefore fill the combustion chamber more quickly at low rpms, and increasing torque. However, this will trade off high end power, because not enough air will flow at high rpms. The opposite can be said for a larger throttle body.

In the case of the neon, the air does not flow directly from the throttle body to the ports, it must make a 90 degree turn right below the throttle body, and then another 90 degree turn into each individual runner, with the runners at the far end from the throttle body getting a more gradual 90 degrees then cylinder 3-4. In this case, the speed of the air entering is more important then the actual volume. With a smaller throttle body, the air will enter faster, however because of the 90 degree angle below the throttle body, the air is going to want to shoot across the bottom of the intake manifold to cylinders 1 and 2, leaving cylinders 3 and 4 to fight for whats left. Air is not going to make a 180 turn into cylinder 1 by itself, and the humps for cylinder 1 and 2 are not sufficient enough to alleviate this. Therefore, with a larger throttle body, the air can move slower, and allow more equal air into each cylinder, and because this is a fuel injected car, the computer will compensate for the fuel difference based on the 02 sensors. I have used a 49mm throttle body, a 52mm throttle body, and a 60mm throttle body, and the 60mm outperformed all the rest on a car with just a header, glasspack, and 3.0 CAI

 

that being said, expresso, do not worry about what other people say about using the 60mm with your mods, just make sure to go back and port out the manifold to match, and make sure its being fed with a true cold air intake

as far as reving up, not much could do that while the gas is not pressedother then a vacuum leak, leak at the throttle body to intake mani surface, or the throttle position sensor being bad

since the stock throttle body uses an o-ring, the tolerances on the manifold might not be as tight as if they had used a paper gasked like the MPx one comes with, if it has even a slight warp from heat, that could cause enough of a leak to do something.

 

with the car off the tach reads 8k but flipping the cluster upside down doesnt seem logical. I pulled the terminal off the battery, trying to get it to reset and it won't. I am testing this TB like I said I have not bored the manifold yet so technically it shouldn't have any issues. I have a AEM CAI on the way for when I do bore it out. I am working on the car as I write this so keep the ideas coming!

 

car is up and running, not sure what I did to fix it