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6Bucs
6Bucs, Ford Senior Master
Category: Ford
Satisfied Customers: 872
Experience:  Ford senior master tech, 18 years experience.
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If my motor wont rev past idle stage is it the motor or a sensor?

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If my motor wont rev past idle stage is it the motor or a sensor?

6Bucs :

Hello and welcome to Just Answer. My name is James.

6Bucs :

I'm guessing the service engine soon and/or the wrench light are on also?

Customer:

yes. I had the motor rebuilt about a year ago. The Tech. told me I need a sensor for the truck to register how much gas the motor needs. Then it just lost all power and I got a Transmission f

Customer:

Transmission fault on my gauges. I cant get the motor past idle stage 1100rpm.

6Bucs :

Are you just revving the engine in neutral, or is this when you drive the vehicle?

Customer:

It's the same in all gears.

Customer:

but the engine doesn't rev. past 1100 rpm. it stays at the same rpm's

6Bucs :

Ok, from what you say it sounds as if the processor is detecting a transmission failure and has reduced engine power to reduce furthur damage. I'd really recommend getting a scan and seeing what trouble codes are in the computer. It's going to be impossible to really tell what's going on until you get that far.

Customer:

The last tech, I just talked to and paid $29.00 said its most deffinentinly a engine problem.

6Bucs :

Maybe I misunderstand...There is a transmission fault message on the dash? Is this a text in a message center, or something on a guage? Does the engine run rough? Any engine noise?

6Bucs :

I didn't know you had a previous question. I've looked it up and am reading that post also, now.

Customer:

text on the guages yes, Motor ran great not rough or any noise until I lost the power. When you start it now it's a little rough till it hits Idle and it's sounds great and not running rough until I give it gas, then its real rough and the RPM's never change.

6Bucs :

Ok. If the message center is saying there is a transmission fault, then that is what the processor is detecting. Exactly what is at fault, we don't know yet, until a scan of the processor. If you don't have a scan tool, some parts stores will rent or loan one to you, if you like. There is a forced limited throttle mode that the engine will go into if it thinks that driving will be unsafe or cause more damage. Most often, the throttle body causes the engine to go into failsafe mode, but You should trust the message center. Do you remember which sensor the mechanic said you would need? Throttle position (tp), mass air flow (MAF), Fuel rail pressure sensor (FRP) perhaps? Also, did this happen immediately when you picked the truck up from the shop when the engine work was done?

Customer:

Fuel rail pressure sensor I think. I know it wasnt the mass air flow or the throttle position. It didn't happen till about 7 months after the rebuild.

6Bucs :

Ok, the FRP is quite important. I've read where the engine only idles, and where it only goes to 1100 rpm. The FRP can definitely cause this. If it has failed, it should definitely be replaced. Still, we need to know what trouble codes are in the computer. You can disconnect the battery negative cable for 10 minutes, which will reset the computer and try it again to see if the symptoms change. This may give you the ability to drive the truck to an autozone, advance auto, etc where they will scan the computer for free for you.

Customer:

I had the battery out all day, it wont drive. Would you recommend the dealersip or the transmission shop? The tech said what ever the sensor or chip, I could only get at the dealership.

6Bucs :

Well, I work at a dealer, so I'm biased that way, just because we have access to the factory diagnostic equipment, parts, service information and messages from the manufacturer.

Customer:

Then thats were I will start, much better advice than the last Tech I spoke with. I feel like I wasted my money

6Bucs :

I'm sorry. You can submit you other question for refund if you are unsatisfied there.

Customer:

How do I doo that?

6Bucs :

Well, our screens look different, but if you go to your account, there should be a link to your questions. There is a drop down menu on my screen where you can submit for customer service/refund. I think it is the same on your end.

Customer:

Thank you very much

6Bucs :

Your welcome. You can always reply back here with follow ups or updates as needed.

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