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Where is the Map sensor?

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Old 03-07-2011, 10:48 AM
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Car: 88 Camaro
Engine: 350, 5.7, TBI
Transmission: 700R4
Where is the Map sensor?

I looked and could find a post on where it is... found out about it (first thought I had a MAF) but not where it is... or where the plug for it comes from cause I cant find it either....

I'm trying to sort out some more crap the PO got it into... I'm idleing high and if I'm running normal speed and coast rpms will drop and rev dropn and rev untill it drops about 10-15 mph... and when I stop it rpms will just all of a sudden drop and it out unless you catch it and hit the gas just a bit and the whole car surges (I stop a bit behind the guy in front of me)...

But in trying to locate it I've run in to a couple more questions... In my air cleaner there are two things, one is a plastic "clamshel" around metal flaps that I believe is a temp sensor I found on the vacuum diagram cause it gets a vacuum line... the one at the top I dont know what it is... looks like a sensor and gets a power plug... and then (last pic) behind the throttle body theres what looks like a sensor coming out of the block that is hex shaped with what looks like a vac line caped off...

Thanks,
Andrew
Attached Thumbnails Where is the Map sensor?-wp_000003.jpg   Where is the Map sensor?-wp_000004.jpg   Where is the Map sensor?-wp_000010.jpg  
Old 03-07-2011, 11:15 AM
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Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Where is the Map sensor?

bolted to firewall flange, has a green connector
Old 03-07-2011, 11:24 AM
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Car: 92 Camaro RS Heritage Edition
Engine: 305 TBI
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Axle/Gears: 3.08
Re: Where is the Map sensor?

You should have a vacuum line coming out of the back of the throttle body running to the MAP sensor. The sensor is actually on a bracket mounted to the firewall, and if I remember correctly it has a 3 pin connector plugged into the bottom of it.

There is a temp sensor in the air cleaner.

On my car, the vacuum line that you have capped off runs to the EGR solenoid.

I've attached a vacuum diagram for a 305 TBI automatic, see if that helps you out some.
Attached Thumbnails Where is the Map sensor?-0900c15280098f34.gif  
Old 03-07-2011, 01:01 PM
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Re: Where is the Map sensor?

On the firewall thanks... I'm pulling it in the garage this afternoon and I'll take a look... Yea I had found a vacuum diagram but thanks ... He had had the back vacouum line going to a T that I think goes to the AC and Vacuum ball... And my egr (maybe) goes to the TB and a metal discish thing right by the EGR...
Old 03-07-2011, 01:59 PM
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Car: 92 Camaro RS Heritage Edition
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Re: Where is the Map sensor?

The back vacuum line out of the TB on mine goes to the MAP sensor. I think the one that you have capped off on the intake manifold goes to a T on mine, 1 of them goes to the EGR solenoid and the other to the canister in the front of the drivers side fender. Then 2 lines come out of the EGR solenoid, 1 to the EGR valve and the other to the front passenger side of the throttle body.
At least that's how the lines were when I got the car. I got it in 2003 with 169,000 miles on it and I'm the 3rd owner. Now it's got 210,000 miles.
Old 03-07-2011, 02:30 PM
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Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: Where is the Map sensor?

Factory, the MAP sensor was on a bracket that bolted to the cowl lip, and kinda hung there right in front of the firewall, not actually attached to the firewall. In your first pic, would be right at upper left corner of the 'lip' where the back of the hood meets the cowl.

Another point I wanted to make - unless the motor has been swapped, that's not a 350 - TBI cars were only available with 305 in the F-bodies. Your sidebar info states 350.

That brings us to ... if you think it's been swapped, then that might be some of your issue - if the swapper didn't do the job right, you might have issues. If a 350 gets swapped into a TBI car, then you have to have 350 injectors installed, 350 knock sensor installed, and a prom chip from a 350TBI car installed into the ECM. So, if there's reason to think it's a 350, you need to check the block casting numbers to be sure, and then check those other things to be sure they were all swapped in as well.

Also, make sure that ALL vacuum lines are either plugged into something, or plugged/capped off. A vacuum leak can make a car run like crap. You can test for vacuum leaks with a can of carb cleaner - with car running spray carefully around all vacuum lines, and around the intake-to-head/block area and the TB to intake area. BE CAREFUL!!! Carb cleaner is very combustible - you don't want to spray alot, just little squirts. If there is a vacuum leak, the engine idle will slightly rev and smooth out for a second when the spray hits the leak.

One other thought - torque converter lock. Might be a longshot, but what you describe kinda sounds like the TC is getting locked, but not releasing. On the driver side of tranny, on the main big part of the tranny, there is a square plug with 3-4 wires - disconnect that plug, then drive and see if symptom still occurs. If it doesn't, then maybe somethings causing the TC to lock but not release.
Old 03-07-2011, 02:57 PM
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Car: 82 TA 87 IZ L98 88 IZ LB9 88 IZ L98
Engine: 5.7TBI 5,7TPI 5.0TPI, 5,7TPI
Transmission: T5, 700R4, T5, 700R4
Axle/Gears: 3.08, 3.27, 3.45, 3.27
Re: Where is the Map sensor?

Upper left corner, bulge in firewall flange, black box w/ green connector. Right next to heater box

Old 03-07-2011, 03:21 PM
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Car: 88 Camaro
Engine: 350, 5.7, TBI
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Re: Where is the Map sensor?

Ok I found it... Hooked it up and gave it a short drive then came home and let it idle... Didn't stall... Still idleing high(I think: 15 and 20 to 25 when going)... And it is a 350... Out of a truck I believe... I got a new tb with 350 injectors and a performance prom for 350... Didn't know about the knock sensor... And converter may be an issue cause starting yesterday when I took it out to get some hose it jerks hard when I but it in drive... Thanks for the help guys...
Old 03-07-2011, 03:32 PM
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Car: 91 Z28
Engine: 350 TPI (L98)
Transmission: 700R4
Re: Where is the Map sensor?

High idle is generally from a rather large vacuum leak, a bad IAC, or someone setting the minimum idle air high to prevent the car from stalling From your pictures it looks like you might have a few disconnected vacuum hoses which could be your sources of vacuum leak.
Old 03-07-2011, 06:28 PM
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Car: 88 Camaro
Engine: 350, 5.7, TBI
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Re: Where is the Map sensor?

Hoses may be leaking, I'll have to check, but from the above diagram they're all hooked up right now... The one you see out is to the air cleaner... The one to the purge canister I have plugged because the solenoid is busted... And the ac/heater because I'm not sure where it goes because it was to the back of the tb... And I don't have a vacuum ball installed... Got one from a junker...
Old 03-10-2011, 10:00 PM
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Car: 88 Camaro
Engine: 350, 5.7, TBI
Transmission: 700R4
Re: Where is the Map sensor?

Thanks got the stalling fixed by hooking up the Map... But the bump when putting it in drive a mechanic at work had suggested that it may be idled to high since its shifting fine... how do i adjust that? he said its either a screw or a ball on the cable but he does mostly fords and wasnt sure which my car was...

Thanks.
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