On TPI motors, the idle air screw (I guess that's what you can call it) is adjustable. Is ours adjustable? If so, how so, because there is a little cover preventing it from being altered. Can the cover be removed safely?

Thanks in advance

 

The throttle bodies are preset from the factory and then sealed so that you can't touch them. Carefully with a small phillips screwdriver and hammer tap into it and pry off, just like removing the lid of a can of octane boost. As the linkage ages, it in later years requires slight adjustment with a torxshead tool to open butterflies back to factory settings Slop in linkage will cause butterflies to close more at idle with age.

 

I used needle nose visegrips and just grabed onto the part of the scew sticking out and adjusted it there. you gotta get them super tight but you only need small adjustments. The torx screwdrive I had was too long and its odd to get at.

a small 1/4 torx bit on a 1/4 drive would work better.

 

One question why do you want to adjust your idle?
If you look on your hood, it will say do not attempt the adjustment of the idle screw several times. *laughs*

 

I follow direction like I follow speed limit signs.

 

LOL yes, I can sense the sarcasm. The reason is it dies when I would come from a dead stop, let off the brake, that split second where no gas or no brakes are pushed, the engine dies, with or w/o the A/C on. Might be because its an old IAC, but hey, can't we just fix it the cheaper way?

 

Look Joe, I explained it the best I could up above. When the unit is brand new they work great, they wear with age. That sticker that tells you not to touch it is for 1)there is no reason to touch it when it works fine, 2) when it doesn't work fine, you take it to the dealer and they charge you $500 to put a new one on. Most of us don't want to waist $500 when we can turn a little screw ourselves.

 

Want cheap?
Fix the old Vacuum hoes.
Usually free
Remove the plugs, media blast them clean & reinstall them (usually free, also).
Check cap & rotor for old age signs (about $20-ish if need new)
Pep Boys & PAW sell Accel brand stuff cheap.
Check spark plug wires at night time for any "electric" leakage.
BY this time, you probably have solved the problem.
Mine still sputters/stalls on initial start up, lately. Could be time for me to change the old Accel cap & rotor. It is three years old by now....
Don't mess with the electric throttle adjustment stuff.
That plan of attack isn't in your best interest.
Find teh real problem, it really may be that simple.
Not like od days of turn up idle screws on carb
Have you adjusted timing?
Sounds like you may need a new timing chain, too.
You over 75K miles on that engine?
Replacing the timing chain brings the idle back to day one specs (atleast if did for me & my original 2.8 in the Firebird).
I was surprised and pleased.
Made the effort well worth it.

 

Finally got around to raising the idle speed, and it DOES make a difference. The idle isn't low anymore (500) but higher, around 700-800 in drive, w/ the brakes, A/C, and lights on. I think I will raise it a little more to get rid of the rattling in the car when stopped at a light.

Karl, the only reason I dont want to do the timing chain, is that I put in a new water pump not that long ago, and I don't want to go through all that trouble when my car is purring nicely now.

 

I wouldn't play with the idle speed, either, unless it was the absolute last resort. Things like a TPS adjustment and IAC motor/passageway cleaning, and even a tuneup, should all be done first. And there's an actual procedure for adjusting the idle speed, find it at https://www.thirdgen.org/newdesign/tech/tpimod2.shtml . This was an actual article that TomK helped put together for Hot Rod magazine, and Tom let thirdgen.org type it up. Not sure about the 450 rpm bit, though, that might just be for a V8. If I remember I'll look it up tonight.

 

I have adjusted mine too. But its stupid, I have learned that. All it is that parts are not working correctly, and your just trying to make up for that with higher revs. Sure the screw should be adjusted if you have added a cam, or something internal. But as far as a stock engine, it is generally not needed, unless its 100-200 rpm bump.

I am not saying waste 500 dollars, but maybe a $70 timing chain and a tune-up might help out what your doing. Its a good cheap clean fix that just prolongs the wearout of these parts.

 

OK, now I feel dumb asking this, but what does the TPS look like on the TB? I'm going to check the TPS later today, when they finish repaving my street, car's all the way down the block....

Edit: I got it, which two wires am I checking for voltage? And I'm checking on the connector on the harness or the connector on the TPS???

Edit again: Checked the TPS, and I backed off the idle screw before I started. It was at .60 volts at idle, so I adjusted it to .55 volts. It seems to have helped a little.

 

I would like a 2 position idle. normal and at a flip of a switch a launch idle.

I have my stock idle at 1000 and i would like to be able to flip a switch or something and have it at 2200

 

I guess racers do that with a rev limiter so even though the they have it floored the ign box will not let it go about what ever rpm. but you are still wide open and could it not flood out or mess with it for a daily driver?

I think like a throtle stop of some kind that would keep it in the 2000-2500 range for a good launch is what I want.

it just hard to keep them like that with your foot, be easier if it held it at 2000 then you can float some more if you want for a good launch.

And then I can keep on eye on the light and not worring about my rpms.

 

One way to bypass needing to do a timing chain swap (for a bit) is to take the distributor, loosen it, twist toward the firewal and clamp it down.
That raises idle, also.
Just enough for a better idle.
Pulling all that stuff off isn't fun.
I just put it all back on, to install the 3.4 under my 85 Blazer hood this past weekend.

FOR FUN,
I'm gonna pull the balancer on the Firebird 3.4 engine. I want to install a sleeve on the balancer neck so it stops leakage from the balancer gasket. Wish I did that detail when I installed the 3.4
Oh well!