A qestion about cold starts

[leonbentz]

I have a 1991 Metro, 1.0 and when I start it cold, the rpm's don't pick up and also, it likes to load up, like it's running way too rich. I'm thinking either ECT sensor or TPS sensor. I've adjusted the TPS and didn't see any changes, but I have a spare.

[leonbentz]

Well, I replaced and adjusted my TPS and no change. Next, I'll try the ECT sensor.

[Rooy]

My guess would be the air valve in the TBI. Take a look here: http://www.teamswift.net/viewtopic.php?t=25522

[RossT]

Thats my post (link) and doctor bills photos that I used. If you remove the TB you can take out and clean the internal spring and air valve. Make sure you count the number of turns that it takes to unscrew it. When you put it back together use 1/2 to 1 turn less, that lets more air thru the TB when cold, thus increasing the idle. I did this to one of my metros that did not give me a fast idle on cold starts. After cleaning and adusting, The idle was much better when cold.

What I did above was only a work around for a worn out TB.

You problem may be somewhere else too.. Air temp sensor, coolant ecm sensor, Map, Isc etc...

[leonbentz]

Cool. Yea, I posted questions about that air valve spring in the past and no one had a clue.

This info here will certainly help though. It seems like this problem started, after I rebuilt the TB. It's most likely I put it back in, too tight and it won't function. Oh well, a simple fix that won't cost anything.

Thanks for all your help guys. I don't know why the Haynes manual doesn't talk about anything on this part. Sheesh, what's with he secrets?
Those dirtbags don't even show an exploded view of the TB. WTF??

[leonbentz]

Okay, well tomorrow, I'm going to work on this "air valve" and try to get my cold start to work right. Is there anyone here who has any input on how to adjust this thing? There has to be some kind of adjustment, when the cap is screwed in from the bottom. Even a good ball park figure would be good. From the bottom of the TB, to the top of the screw in cap, there must be some kind of depth that will be a good place to start. If anyone has a TB on the shelf, it would be helpful if you can give me some input. I ordered a couple base mount gaskets, so I can remove and replace the TB more than once, if necessary, but I hope I can get someone here who has done this before. Thanks for the help I have got so far.

[RossT]

The FSM (factory service manual) has a procedure to adjust spring mechanism. It involves putting the TB in hot/warm (at a certain temp) and the valve should close at that temp. I don't have the manual in front of me, but there are some links to the manual over on team swift.

One last thing you should do BEFORE you mess with the TB again, is to remove the ecm coolant sensor, and clean out the coolant passage to and from the sensor. Others have had issues with the passage becoming clogged and not allowing coolant to reach the sensor, thus the ecm reads an incorrect value from the sensor. Its located on the top backside (firewall side) normally the connector is green or blue.

[RossT]

Here is a link to FSM pic on team swift:

http://www.teamswift.net/viewtopic.php?f=5&t=28842

If you can't find the waterbath thing there, I can scan it for you.

I know with mine I never used the water bath, I just undid the valve, cleaned out the crap with carb cleaner, screwed it back in, but used 1 turn less than it took to unscew it, thus increasing the amount of air entering the TB when cold and increasing the amount of time it take for the valve to close until warm.
The wax matrix pellit thing expands with coolant increase in temp. That expansion closes the valve when warm.

[leonbentz]

RossT.

Thanks for gettin back. Do you think that there may be a depth, to screw in the cap in, from the bottom surface? That would give me a good ball park figure to start with. If you can't help me, then I can always go to U-Pull it and take one off and measure it.

I found a lot of these, with the injectors ripped out of them, so maybe I can just pull the bottom half and use it as a study piece. I've worked in the machine shops for years, so all I need is a pair of dial calipers to guage the depth of the cap. If I can do that, then I'll have something good to go by.

I seem to remember, it worked before I rebuilt the TB. I picked up an extra 4 miles per gallon, but my car idled too low at start up. I think I just twisted in the little metal cap in to far. I bought two TB base gaskets, so I can work with it. It seems to be a simple task. I rebuilt the TB, before my cup of coffee got cold one morning.

[RossT]

If you find one in Junk yard, just count the turns to remove it. I want to say mine was 8 to 12 turns to get out, but I didn't write it down.

You may just want to start baking the vavle out by 1 turn at a time, then test for a couple days. Keep doing that until you are happy with the cold start. When you are happy, then replace the TB gasket with your new one.

I know on my 91, backing the valve off by about 1 turn really helped!!

[RossT]

Here are a couple of FSM scans, sorry for the bad quality.

[leonbentz]

Thanks for posting the stuff. It is very much appreciated.

This weekend, I'm going to the U-Pull it and checkin' one out so I can get a good idea on where to start. Usually people tear those apart and rob the injector out of them, because they are over 400 bucks new. Fortunately, I have a reman, in my car and two used ones, so I'm set, for injectors. So, if I find one of these throttle bodies in a car there, I can remove it and spec it out and even buy a partial throttle body, for the spring and valve. Since the high dollar part is gone (almost the price of an engine) I should be able to get a gutted throttle body pretty cheap.

[leonbentz]

Well, I went out and adjusted the Air Valve and by golly, I just about have it in normal operating range. It looks as though each turn will change the duration of it. Pretty cool huh? So, if any of you want to increase, or decrease the duration of the fast idle, just pull the throttle body and go a quarter or half a turn each way, to adjust it.

Thanks for all your help guys.opcorn: I'll let it cool down and check it again, and see how long it takes to idle down.

[RossT]

Thanks for the update.

[leonbentz]

Well, I gave the cold start another test this morning, after letting it sit all night and letting it cool down completely. It worked beautifully.

It started idling down right about the time the needle on the guage came off of the C. So, after I saw that it worked good, I went ahead and replaced the TB base gasket and called it good.