Hey guys I know FCDs been covered a lot and I have been searching. I have a RB FCD I bought from a member on the forums a little less than a month ago. I just got around to installing it and as soon as I plug it in my boost guage pegs out.

Now the car can still drive and idle but just doesnt perform well, I was reading post about these guages and supposedly there is a pot inside of it you can adjust to change the clamping.

My question is, if it is peging the guage immediately, is something else wrong, or does it just needs to be adjusted? Or is the FCD Busted? (The stock boost guage worked before and still works when i remove the FCD.)

Thanks a lot for the help guys,
Dane

 

looks like busted FCD or wrong connected (doubt its possible)

 

Well, you just connect the FCD inline correct? You plug the connector that went to the stock boost sensor into the FCD, then FCD into stock boost connector? Is there any way to test for a busted FCD? Instead of simulating boost on it?

Also if it is busted then in theory i shouldnt be able to boost... I can boost the same as I did before I installed the FCD but the idle is just lower, and at 4krpm exactly everytime I hit this spott that is like a wall, it will increase RPMS but doesnt accelerate. And I can smell fuel.

The symptoms to me sounds like its running extremely rich at that point, so rich it can't fire. I don't know, any feed back would be appreciated. I appreciate the quick response.

Thanks
Dane

 

If your boost gauge pegs, ECU gets wrong info and map is screwed. Maybe in safety mode?

However, it does not affect turbo from spooling and boosting, as long as engine runs ;o)

I would remove FCD and sent it back or called RB to get info what could be wrong (do you have correct one matching your series of car?)

 

Yeah the guy I bought it from had a S4.. I do have a 10thAE though, maybe its something to do with that. Because the guy who sold it to me seems to a pretty upstanding guy and he said he boosted 15psi on it no problem. But his car was a NA converted to TII so it didnt have a stock boost sensor. Anyhow I geuss I will give RB a call, but do they warranty stuff that is bought second hand?

Thanks
Dane

 

ask what boost sensor did other guy had with it working

 

N318 boost sensor is the sensor he was running with the RB FCD, and said it was working. It is untouched on the inside, everything looks like it should (Has the stuff over the pot as people described and it all looks clean) What things could make the FCD peg the stock boost guage? When it is pegged if I go and boost the car the needle shakes a little so I know it is still trying to register something.

(Just to clarify, by pegging it out I mean it is saying I am max boost all the time.)

 

You say the car runs and idles but does not perform well. The car or the boost gauge? If it's the boost gauge you are referring to, according to Racingbeat:

The Fuel Cut Controller allows the Turbo II to run at higher-than-stock turbo boost pressures without experiencing pre-programmed rear rotor fuel cutoff. The Fuel Cut controller essentially deceives the ECU (computer) into thinking the boost is not as high as it actually is. Consequently, the stock boost gauge no longer displays accurate boost pressure.

Don't get me wrong, That might not be the issue at hand but I thought it might give you some insight.

I suggest you get an aftermarket boost/vacuum gauge because my boost gauge was inoperable after installing the FCD.

 

YOu NEED to take that thing off the car before you fry something.

YOU NEED to put the car back as original and then put a meter on the boost input wire at the ECU and read the voltage with the key to ON only and compare that to the FSM reading.

The reading should not change at the boost gauge because you have a FCD on the car. The gauge will read NORMAL until you reach somewhere around 8psi give or take.

And for accuracy...........the boost sensor has an output wire. It is brown/red. It feeds two items. One is the boost gauge and the other is the pin 2B on the ECU. The ECU does not in any manner make the boost gauge move/react.

With the key to ON, the voltage at the pin 2B should be b/t 2.3vdc to 2.7 vdc. IF it reads 4.5 to 5.5vdc you have the wrong boost sensor in the car.

You should confirm that you have the right sensor in your car.

 

Thanks for the input HAILERS. I removed the FCD after the first test drive, so yes it has been off to make sure no damage results. I am the third owner of this car and I personally never replaced the boost sensor but maybe one of the previous owners did and they put the wrong one in. I always thought the S4 and S5 boost sensors have different harness plugs so you couldnt possable install the wrong one, am I wrong?? Either way I will check the voltage tomorrow morning and post everything I find.

Thanks a lot again guys,
Dane

EDIT: I just was looking for the pressure sensor on Mazdatrix when I came across their brand of FCD. Their picture looks exactly like the one I got, I was wondering if they sell the RB one or is that Mazda's brand?