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Throttle Body Screw; Factory Setting
Topic Started: Aug 15 2014, 04:23 PM (751 Views)
Duck Sauce
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So does anyone know the factory setting of the screw on the side of the throttle body? Is it open, closed, in the middle, or somewhere in between. If someone knows how many turns from one of those it is I would appreciate the info.
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cwatkin


I wish people wouldn't mess with this. I had this on one of mine where they had messed with this as well as the TPS. Getting the TPS back to where it should have been was a real pain!

Conor
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dayle1960
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Fastest Hampster EVER

Have you turned that screw yet? I hope not, because if you did, then you are in for a bad time.

Your best recourse is to turn it a little bit at a time. In about a week you will find the sweet spot. Patience is your friend.
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Duck Sauce
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I didnt mess with it but the previous owner said he did. I looked for it online but couldnt find anything.
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dayle1960
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Fastest Hampster EVER

Look, you might/might not be in a world of hurt. If the PO touched that screw and adjusted the TSP, then your metro will probably run like crap. If he didn't touch it, and your whip runs like crap, then something else is wrong. Once the TSP is set at CAMI, then there should be no reason for it to ever be touched.

I bought a metro that had a re-set TSP and it ran like a sick dog. It had no guts and I had to keep my foot on the gas the whole way home. I got very lucky and adjusted the TSP to the mid way point. It did wonders for the running of the engine. It really was a miracle that I hit the sweet spot on the first try.

IF, and I stress IF, you mess with the TSP, you really need to take a pic of the TSP BEFORE YOU MESS WITH THE SCREW. You will need a reference point and the pic will create one. When you start turning the TSP, do so at very very slight increments. Turn the TSP slightly and run the metro around the block. If no-go, then park the metro, twist the TSP slightly, and repeat. It will be a very long process, but it is the best way to fly in the dark.

Hope this helps.
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myredvert
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myredvert

When I bought my Vert, it was obvious from the screws and marks on the base that the TPS had been messed with. While I didn't have any noticeable problems with the TPS operations, Geo Glenn gave me a rundown on the FSM procedure setting the throttle stop screw and the TPS with a multi-meter and a feeler gauge, I set it to those exact specs, and it has worked flawlessly. Thanks Glenn! :thumb

As far as the idle screw, the FSM does not list a "factory" setting for the screw, and there is no "right" setting that fits all for all vehicles as each engine will perform differently, but the procedure and specifications for properly setting it is in the FSM, Section 6E2-C2, DRIVEABILITY AND EMISSIONS. While it assumes you are a "service tech" type using a Tech 1 scan tool to also adjust the IAC Duty settings at the same time, you can still set the idle, timing, etc. When I first reinstalled my engine my IAC was still not operating correctly, so I had to set the idle up slightly to handle increased electrical loads. Once I got the IAC "rebuilt" and functioning much better, I set the idle back down to the recommended setting. If you have "factory" Air Conditioning, you also need to check the operation of the AC Solenoid Vacuum Valve as part of the process.

And to set the idle properly, the timing first needs to be set. If your car does not have a tach, I would recommend getting your hands on a tachometer or dwell/tach meter so the timing can be properly set at the correct rpm first, then work on your idle setting and set it by the numbers and see how that works for your engine.

And it also can't hurt to either carefully check (or better yet just replace) all the small vacuum lines and verify their routing is correct first as well. 20+ yr old vacuum lines can have issues that will mess with your idle and can be hard to track down, and vacuum hose is cheap and might prevent a lot of chasing and headaches later.
:cheers
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cwatkin


The problem is that the idle stop screw serves as a reference point for TPS adjustment. If it has been messed with, this makes proper adjustment of the TPS all that more complicated. I had to adjust my TPS by trial and error. Too rich and it acted like it would flood out at first startup. Too lean and it would start to idle really high with a surging pattern once warmed up. There is a very small window to find if you have to do it this way which isn't fun.

The 1994 advanced emissions is the one this happened on. It was causing the ISC to misbehave badly and caused much of my revving idle problem.

Conor
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Metromightymouse
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Powdercoat Wizard

Since no one has mentioned it yet, the easiest solution to this problem is probably to go to the JY and pick up a throttle body off another metro that hasn't been molested.
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clarkdw


No one has questioned which screw on the side of the TB. A 93 will have two. One is the throttle stop screw "the screw that must not be touched" and the other is simply an idle speed adjusting screw. The throttle stop screw is the small screw requiring an Allen wrench to adjust. It normally has a plastic cap over the end of it from the factory. The idle speed screw is the one requiring a straight screwdriver to adjust and faces into the throttle body so all you can see is the head which is normally covered by a plastic plug. Two different screws each requiring it's own setting.
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myredvert
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myredvert

Quote:
 
The problem is that the idle stop screw serves as a reference point for TPS adjustment.
Sometimes you gotta do what you gotta do. My stop screw and TPS had already been messed with by someone previously. And when Glenn gave me directions on how to set the stop screw he wasn't talking about it as if it required some double secret PFM that warranted throwing everything away and trying to find an unmolested one.

I followed Glenn's instructions for setting the stop screw and TPS (TPS instructions in the FSM), and after not a whole lot of minutes with a feeler gauge and a multi-meter the stop screw and TPS were set. Then I adjusted the idle, the timing, and messed with the IAC pen spring length a few three times over a few months before I got it to function fairly normally.
Quote:
 
No one has questioned which screw on the side of the TB.
Good idea to clarify. :cheers

From the way the OP was describing it, I took it to mean (otherwise known as assuming :O ) that he was talking about the idle speed adjustment screw and not the throttle stop screw. I suppose "open," "closed," "somewhere in the middle," and "how many turns" could apply to the stop screw as well?
Edited by myredvert, Aug 16 2014, 07:50 PM.
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