quick turbo pressure sensor question

[seoul4korea]

91 with a 1J
I was working on the supra today and I went to pull off my turbo pressure sensor today while the car was running (located drivers side) and when I unclipped it and my rpm's dropped to 440 rpm's insteed of the normal 650ish. I'm not sure what to think of this because when I plug it back in it goes back up to the normal. Any idea's?

-Chris

 

[te72]

Hmm... did you pull the sensor located between the brake master cylinder and shock tower, or the one that most people put on the firewall? If it's the first one, I have no idea what would cause your rpms to drop, but if it's the latter, you likely pulled your MAP sensor. I believe you and I have discussed the differences between the two sensors in another thread though, I'm sure you know which one you pulled for sure.

 

[seoul4korea]

Yes I know the difference and I believe we have talked about this before. I know know it's not the MAP because I just change that sensor + it's still connected to the vaccuum line to the mani. The turbo pressure sensor ass. is plugged in (wiring harness) but not from a vaccuum source. The sensor is located by the master cylinder as well. the harness for it comes up through the drivers side fender area. If I pull my MAP while the turbo pressure ass is disconnected the car dies. I tested this to make sure my car would throw a code (and that the bulb wasn't dead) that way I know if the turbo pressure ass. would throw a code or not, which it doesn't. Any ideas?

 

[te72]

Well, you say the stock boost gauge sensor isn't hooked up to a vacuum line, but it is hooked up through the harness? Mine's the exact opposite, vacuum hooked up, wiring is not, mine's idling fine, no codes. Might give that a shot, although I suspect that your problem lies elsewhere. Have you checked all the vacuum lines on the intake itself? I was working on mine this last week and accidentally slipped a couple vacuum lines off... that really shouldn't matter though, being map based.

You didn't specify why you unplugged it in the first place though, trying to clean up the bay a bit? I wouldn't mind doing that but haven't gotten around to it. Any reason you can't leave it hooked up for now? You said all was fine when it was hooked up...

 

[seoul4korea]

Yeah I'm working on my E-manage atm and was just looking around in the engine bay for a good spot for the 2bar map sensor when I saw it again (looked at it before) I tried unpluging it just to see what the effects where and that's what I got. I actually just made a boost leak tester and did it a few weeks ago. I had one somewhat big leak that i fixed but could really find much more. I did say I unplugged it looking back but I think where I messed up was using the word unclipped. Thinking I'll just keep it plugged in till I figure out the main reason for this.