Pressure sensor disconnect or not?
Rotary Enthusiast
Joined: Oct 2002
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From: The Boro, TN
I have heard that bad things will come, From what i have heard, there was no real understanding of this, or if the ecu pulled codes from it some or all of the time, but i dont think that it is a good thing to do.
-CHris
-CHris
FC Mobsta
Joined: Sep 2002
Posts: 1,825
Likes: 2
From: Olympia, WA
Re: Pressure sensor disconnect or not?
Originally posted by Angel Guard Racing Team
What would happen if I disconnect the air pressure sensor? Would that cause my secondaries not to work?
What would happen if I disconnect the air pressure sensor? Would that cause my secondaries not to work?
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Rotary Enthusiast
Joined: Jan 2002
Posts: 975
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From: Puerto Rico Land Of The Fastest Rotaries
Mine is an 87 auto ecu n/a BUT... Turbo, 91 TII intake manifold and side housings. I just want to make sure those secondaries come online all the time, I got 550cc primaries and 720 Secondaries, the car starts fine and runs fine I just wanna make sure those secondaries will come online under load... Remember I am talking about pressure sensor not boost sensor my car was n/a.
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
If you disconnect the vacuum tube, the secondaries will come on at around 3800 rpm each and every time you hit 3800 rpm.
If the vac line is connected to the pressure sensor, then the secondaries may/may not come on when you hit 3800 rpm. If your car is under a load, they will come on at 3800rpm. If you are pressing on the pedal and accelerating at a moderater pace, then they may never come on line. I've driven 80 plus mph without them coming online(no load).
You should not run with the line off the sensor. It screws up the ECU's maps. As in fuel injection timing. See the 89 manual, fuel section, RELATIONSHIP CHART.
Also take the above into consideration when you pour a bottle of fuel injection cleaner in the car. Great for primary injectors. Wishy washy for secondaries, unless you continuously stay hard on the accelerator above 3800 rpm (where they work). Not ***** footing above 3800, but hard on it. As soon as you stabalize the throttle above 3800, they will probably shut down. Get the picture????
If the vac line is connected to the pressure sensor, then the secondaries may/may not come on when you hit 3800 rpm. If your car is under a load, they will come on at 3800rpm. If you are pressing on the pedal and accelerating at a moderater pace, then they may never come on line. I've driven 80 plus mph without them coming online(no load).
You should not run with the line off the sensor. It screws up the ECU's maps. As in fuel injection timing. See the 89 manual, fuel section, RELATIONSHIP CHART.
Also take the above into consideration when you pour a bottle of fuel injection cleaner in the car. Great for primary injectors. Wishy washy for secondaries, unless you continuously stay hard on the accelerator above 3800 rpm (where they work). Not ***** footing above 3800, but hard on it. As soon as you stabalize the throttle above 3800, they will probably shut down. Get the picture????
Last edited by HAILERS; Nov 5, 2002 at 12:15 AM.
I'm a boost creep...
Joined: Jan 2002
Posts: 15,608
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From: Auckland, New Zealand
Re: Pressure sensor disconnect or not?
Originally posted by Angel Guard Racing Team
What would happen if I disconnect the air pressure sensor? Would that cause my secondaries not to work?
What would happen if I disconnect the air pressure sensor? Would that cause my secondaries not to work?
The question is why? There aren't any benefits to doing this, only downsides.
Senior Member
Joined: Mar 2002
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From: Treasure Island, FL
Joined: Feb 2001
Posts: 29,798
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From: London, Ontario, Canada
Trust me, your secondaries are coming online as soon as you bring the car out of vacuum (assuming RPM>3800).
They come on at 3800 RPM if the engine is under load. No, they don't usually malfunction. Yours are working. 
how do you know when your secondaires are comin online?
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
Heads up on what NZ said about the IGNITION timing and the boost/pressure sensor, please.
That said, I've put fuel injector cleaner in the gas tank, pulled the vac line, and driven at hwy speeds just to make sure the fuel injector cleaner was actually passing thru the secondaries, and doing some good. Sounds a bit goofy, but it just does not make any sense to me, to put fuel injector cleaner in the tank with everything connected up, because the secondarys only open or inject under load over approx 3800. If done that way, only the primary injectors are getting the benifit of the cleaner. Yeah, I know it sounds goofy and extreme.
Side note: I have no idea why my fingers wrote *moderater*, instead of moderate, in my earlier post. My spelling shore ain't what it should be.
That said, I've put fuel injector cleaner in the gas tank, pulled the vac line, and driven at hwy speeds just to make sure the fuel injector cleaner was actually passing thru the secondaries, and doing some good. Sounds a bit goofy, but it just does not make any sense to me, to put fuel injector cleaner in the tank with everything connected up, because the secondarys only open or inject under load over approx 3800. If done that way, only the primary injectors are getting the benifit of the cleaner. Yeah, I know it sounds goofy and extreme.
Side note: I have no idea why my fingers wrote *moderater*, instead of moderate, in my earlier post. My spelling shore ain't what it should be.
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