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Defi Boost Install Problem


Greg_STL

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I had my BBK and Boost guage installed a while back and the guy who did it butchered my brakes (cut the lines, stripped the ABS module!!) and walked away from the install. I was most worried about my brakes and got those fixed first. The boost guage had everything connected and at first blush appeared to work but does not. I've finally gotten around to try to find out what is wrong with it. I was just too mad for a long time to even let myself work on it.

 

Basically, any time the boost reaches ~11 psi the guage will reset.

 

It will go through the opening sequence on start up and as long as I never reach 11 psi the guage will read what appears to be accurate values. It also goes through the proper shut down sequence when the ignition turns off. If I accellerate quickly it will reset immediately but on a long slow climb in 4th or 5th gear I can sneak up on the 11psi range and then it will reset. By reset, I mean the boost guage will go through the opening ceremony and then start reading again. If I'm still over 11psi it will reset again.

 

I originally thought it was a loose wire that was dropping out during hard accelleration. I re-did the existing connections and I no longer think its a loose wire. That does not mean I'm positive the wires go to the correct locations.

 

The red and illumination wires are connected together and to a wire that runs directly to the postive battery terminal. The ground wire runs directly to the negative battery terminal. The ignition wire connects with a tap to a wire leading out of the ECU. At the time, the guy said he looked up the pinout to make the correct connection. Not sure one way or the other but since it comes on when the ignition comes on and goes off when the ignition is cut, I have a feeling it is not the problem.

 

The boost solonoid is in the engine bay on the driver side with a tee between the manifold and fuel regulator. Originally, he had it mounted horizontally and I adjusted it so it is mounted with the air hold down as the manual indicates. I'll try to take a pic tonight in case this is the issue.

 

I'm stumped at this point and I can't really go back to the butcher. Any help would be much appreciated!!!

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I got power for my boost gauge from fuse 14 and ground from the gold bolt that holds the fuse panel on. I have had this since last fall with no issues. I would check your ground wire.

 

My boost/vac source is my BOV. I have not seen any other installs using the manifold, but I imagine that will work just the same. Do what John above says, that might be a fire hazard.

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I don't think it is a fire hazard as much as if it blows off your fuel won't increase in pressure under boost and you would have a lean condition. I guess I need to find some vacuum hose and move it to the BOV location.

 

I've checked the ground wire several times and it goes straight to the battery. Not sure what else to do there... Do you think moving to the BOV location would possibly fix the reset issue????

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I don't have the same gauge, but I don't think the reset has anything to do with the boost/vac source you have. It has to be electrical, and by how you discribed your install guy I doubt its a bad gauge. I would move the ground wire from the battery to a solid chassis ground.
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Does the sensor itself have to be grounded? I just installed a cyberdyne fuel pressure gauge and they expected the sensor to be connected and grounded to the block somehow (ya, wtf) so I wound up connecting a ground wire to the base of the sensor, e-taping it, and grounding to a earth point on the firewall. can't say I recall having to do all that for a autometer e-FP sensor.

2012 Forester XT. Stage 2+

Retired from Racing. I used to build FMIC and more.

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The senser plug only connects to the main control unit. The guage connects to the main control unit. The control unit has the four wires to it that tie to power, ingnition, illumination and ground. I re-did all four wires (except the illumination tap at the ECU) and it made no change in operability.
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Exactly. If you lose the FPR signal you will go lean. And we all know what happens under boost when you go lean, right? :)

 

FWIW, I've sourced my boost guage at the BOV. Not the optimal place, but IMNSHO much better than the FPR line.

 

I don't think it is a fire hazard as much as if it blows off your fuel won't increase in pressure under boost and you would have a lean condition. I guess I need to find some vacuum hose and move it to the BOV location.

 

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The red and illumination wires are connected together and to a wire that runs directly to the postive battery terminal......

 

Unfortunatley, I do not have this particular gauge set, so I can't be sure if your hookup is correct. Hopefully, other memebers here can confirm/reject....

 

My question currently is what do you mean by the sentence quoted above.

 

What's the "red wire" supposed to be? :confused: If that's the "constant 12V power" wire, as with my AutoMeter NEXUS control unit, then yes, I can see why that's going there (assuming that it's fused).

 

Also, why does the illumination wire tap straight to the battery terminal? Wouldn't this cause the illumination to remain "on" at all times, even when the vehicle is "off?"

 

Sorry, bro, I truly wish I could help you more on this, but to me, all that I can say is that this sounds like either a wiring problem, or gauge problem.

 

Speaking of that last issue - is this gauge programmable? If so, are you 100% certain that the reset is not due to resident memory/preset?

 

Best of luck! :)

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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