My Car Won't Stop Reving To The Max

[420Adriver]

Ok I went to go out and start my car today and the minute I turned it on it started to rev uncontralably and would not stop. I turned it off before it blew my engine. Of course I checked all the basics, there was nothing holding my throttle body cable down. My tps sensor is still good and the gasket on my throttle body is not blown, I was sure one of these could be it but it wasn't, I am stumped.

 

[TheRealist]

Try This, Disconect your Negative batery terminal leave it off for about 3 to 5 minutes then reconect it. see if that helps.

 

[nightspeed87]

ive never heard of this... And your throttle cable is ok right?
Take off your intake arm and look at the throttle body while its on, I dont see how the engine could rev up like that without the throttle plate opening... If its opening check the cableing and the other sensors in that area, and do you have a check engine light or anything else wierd that could cause this?

 

[donmagicjuan]

If you have cruise control, check to see that it hasn't failed by observing it after starting the car. Just have a second person in the car to shut it off quickly.

 

[420Adriver]

I forgot to post that I did that with the battery already, and nothing happened. I don't know if this might help but the car was ran with the safc2 disconnected for a time when we were putting on parts and I just hooked it up for the first time with the proper setting. I don't know if this is possible but what I think happened is that while it was disconnected the cars computer readjusted to not sensing a maf sensor and now that it has it back its acting crazy again. We did a vacuum leak test and there is none, and my settings are right on my safc so thats not the case.

 

[420Adriver]

ive never heard of this... And your throttle cable is ok right?
Take off your intake arm and look at the throttle body while its on, I dont see how the engine could rev up like that without the throttle plate opening... If its opening check the cableing and the other sensors in that area, and do you have a check engine light or anything else wierd that could cause this?

Yes my check engine light is on but it has nothing to do with this problem, it has been on since I ran a high flow cat and blocked off my egr.

 

[420Adriver]

If you have cruise control, check to see that it hasn't failed by observing it after starting the car. Just have a second person in the car to shut it off quickly.

I do have that but how do I check to see if it failed?

 

[NewTurboTuner]

Yeah I had a cousin who's car would go WOT for not reason... while he was driving!
It turned out to be bad cruse control.

 

[nightspeed87]

maybe theres a way you could disconnect cruise controll all together to see if this fixes the problem.

 

[donmagicjuan]

The difference in your engine bay will make this a little more difficult to describe, but it should be simple enough. Trace the throttle cable back from the throttle body until you get to the cruise control actuator. It might have a little plastic cover on it. If it does, pull it off to expose the cable connection. Mine looks like the picture close up. Verify your throttle is shut before starting the car. Then when you start the car, see if you can tell if it's opening the throttle.

 

[420Adriver]

I don't think thats the problem, I completely disconnected the throttle body cable to see that since I don't have a second person and it still did it. There was no way possible for the tb to open if the cable was disconnected right?

 

[donmagicjuan]

I don't think thats the problem, I completely disconnected the throttle body cable to see that since I don't have a second person and it still did it. There was no way possible for the tb to open if the cable was disconnected right?

Yep, that's enough to convince me. Have you checked that all the ports on your intake manifold have their respective vacuum lines attached? A disconnected PCV valve line could cause overrevving at idle.

 

[420Adriver]

I checked that right now and they are all connected tight.

 

[donmagicjuan]

Also, if you have a CEL from a prior existing condition, how will you know if you have any new issues develop? Obviously, you can't drive it to an auto parts store to have the code(s) pulled right now, but if you have access to a scan tool, I would check that out as well.

 

[1990talon]

if you disconnected the cable and it still does it some how you must either have somthing hanging the throttle body up if it is going clear to red line. that thing has to be open if you gaskets not blown around the throttle body and the leak down test checked out ok take off the intake pipe and look in to see if the plate is open if that isnt the case then i dont know what to tell you.

Good Luck

 

[ekanddsm]

Not to add insult, but is the throttle body actually closed, have you take the air boot off to see. If that was cool, then I would unplug the coils and crank it over for a few seconds and when it stops cranking listen for a vacuum leak. Sound kind of cheesy but sound like a vacuum leak to me.

 

[420Adriver]

Yes I did all that, . I just want to get this figured out, I have had this IM off three times and this is gonna be my last time. We literally made sure everything was tight, I replaced almost everything just because I wanted a dependable ride, the leak tests were done a few days ago. This car has even been ridden in maybe 10 miles since we fixed it. It started up 3 minutes before it did this and I doubt its a blown gasket anyways because why would it start fine then not? When it started the maf sensor was disconnected by the wire because the safc2 was and the car ran excellent considering it had no maf sensor. Then I hook up the safc2 that had all the proper settings and it started to run like this. I even took the time to unhook the safc2 and it still ran like that. I had this car running excellent a few days ago know this.

 

[donmagicjuan]

Well, air has to be getting into the engine somehow, either through the throttle body directly or a leak in/around the manifold. The car won't overrev simply because the ECU thinks there is more air entering the engine than what actually is-- at least not to the extent you're seeing. I know you have an N/A, but look into performing the equivalent of a boost leak test on your intake system. Normally, the way to check for vacuum leaks is to spray starter fluid around possible leak areas and monitor for a change in rpm, but in your case that's not feasible.

 

[420Adriver]

Would something like a boost leak test work? I don't think I would have enough time to do all that w/o my engine blowing? What I was wondering is if there is anything that you could spray around possible leaks and see where air is getting in real quick like as soon as I turned the car off and on it would show where the air was coming in by where I sprayed it.

 

[donmagicjuan]

Would something like a boost leak test work? I don't think I would have enough time to do all that w/o my engine blowing? What I was wondering is if there is anything that you could spray around possible leaks and see where air is getting in real quick like as soon as I turned the car off and on it would show where the air was coming in by where I sprayed it.

Yes, a boost leak test is performed with the car off. That's why I suggested it, as any test with the car running is pointless in your situation.

It consists of pressurizing your intake system with a source of compressed air, and then poking around listening for where the air is rushing out.

 

[420Adriver]

I have never done that before but it actually sounds pretty smart, so what would I do just get like a air tank and blow air in my throttle body and listen for where air is coming out or what?

 

[GVR4592]

I forgot to post that I did that with the battery already, and nothing happened. I don't know if this might help but the car was ran with the safc2 disconnected for a time when we were putting on parts and I just hooked it up for the first time with the proper setting. I don't know if this is possible but what I think happened is that while it was disconnected the cars computer readjusted to not sensing a maf sensor and now that it has it back its acting crazy again. We did a vacuum leak test and there is none, and my settings are right on my safc so thats not the case.

Did you remove the maf sensor? What do you mean when you say the ecu readjusted to not sensing a maf sensor?

 

[420Adriver]

I didn't remove the maf sensor, but when you install an safc2 on my style you have to cut the maf sensor wire going to the ecu in half (the only wire you cut in half for the ecu) and you hook it into wires on the safc2. When i didn't run with my safc2 it was basically the same as not having a maf. And when I say readjusted i meant that as a guess, seeing as my car readjusts to compinsate for something new in the system after 5 day, like when I put my lightweight underdrive pully I didn't feel the full effects of it till a couple days later when the ecu adjusted to compinsate for the light weight. That was my theory of why it could be reving this high uncontrolably.

 

[GVR4592]

OK I still don't get it. I understand the wiring of the safc, it's the same on every car, and I've done a dozen or so installs. But how is it the same as running without the sensor? The car won't run without the sensor....well it will run, but it will run like ass and it probably wouldn't rev very high.

 

[420Adriver]

Its the same because the signal isn't getting back to the car, isn't it? and yes the car did run like an ass w/o it. But there was absolutely no wire getting back to the ecu for the maf sensor hence whatever it was reading couldn't be sent back to the ecu. And I know for a fact that the wiring diagrams are not the same on all cars, there was wires I didn't use. I had to find out what the wires where for and locate it on my pin diagram of my ecu.