Hope this qualifies as "Tuning".
Okay... I drive a '94 Cavalier with a 5MT. (I love my car)
When I go to shift to 2nd gear, the only way I can match the shift with my natural shift timing is to wind it up in 1st past the sweet spot to shift to 2nd. I'm fine with that. However, it takes a moment or two for the revs to drop to the sweet spot, and I've already got the shifter in the gate, and I wind up waiting for it. Somebody told me that if I make a new gasket for my IAC, with smaller holes, the revs will drop faster. That would be nice.
Any advice on that?
I was also told about "dashpot", which I only know what it does.
I've also been told that I could take it out of the ECU.
Exactly how would I do that?
I'd love to have the revs drop, instead of hanging there for a moment...
Any help or advice would be appreciated.
Just a warning, I don't have a huge amount of cash on me at the moment.
So, if it's going to cost a lot, I won't be able to do it.
However, if I can do anything about the revs hanging, and the solution is in my price range... *tears into car to modify*
That will be the outcome... If there's anything I can afford to do about it, I'll go right out and take care of it.
"Would you go with me, if we roll down streets of fire?
Would you hold on to me tighter, as the summer sun got higher?
If we roll from town to town, and never shut it down?"
-Excerpt from "Would You Go With Me", by Josh Turner
Well... this is mostly going to be bad news. The throttle follower is a calibration value in the ecm which dictates how much the IAC opens and closes when the throttle is opened and closed. GM tuned the 2.2 5 spd cars so the IAC doesn't close quickly when the throttle is lifted. I always hated this on the 93. I learned that letting the clutch pedal up and pressing the gas at the same time would allow me to shift.
Start by checking to see that the throttle blade is adjusted properly. Look for .5V + / - .25 to indicate a correct setting. If your ecm part number is 16191947 then there's software available to burn a chip.
If you can't or don't want to mess with the chip then you might be able to try different IAC motors to see what happens. I know you can use one from a 92-94 Sunbird with 2.0, and there are probably a few others which will bolt up. What you need to do is look at the shape of the pintle, the pointed portion of the IAC which seats against the throttle body to restrict airflow. You want one which is flatter, one which gets larger faster so it takes less movement of the IAC to restrict more airflow.
What sucks about this is the only way to do it without spending a large amount of $$ is to spend time at the junkyard removing IAC's and comparing them to yours.
hth
-->Slow
slowolej wrote:Well... this is mostly going to be bad news. The throttle follower is a calibration value in the ecm which dictates how much the IAC opens and closes when the throttle is opened and closed. GM tuned the 2.2 5 spd cars so the IAC doesn't close quickly when the throttle is lifted. I always hated this on the 93. I learned that letting the clutch pedal up and pressing the gas at the same time would allow me to shift.
Start by checking to see that the throttle blade is adjusted properly. Look for .5V + / - .25 to indicate a correct setting. If your ecm part number is 16191947 then there's software available to burn a chip.
If you can't or don't want to mess with the chip then you might be able to try different IAC motors to see what happens. I know you can use one from a 92-94 Sunbird with 2.0, and there are probably a few others which will bolt up. What you need to do is look at the shape of the pintle, the pointed portion of the IAC which seats against the throttle body to restrict airflow. You want one which is flatter, one which gets larger faster so it takes less movement of the IAC to restrict more airflow.
What sucks about this is the only way to do it without spending a large amount of $$ is to spend time at the junkyard removing IAC's and comparing them to yours.
hth
-->Slow
Well, I'll be going to a junkyard soon anyway.
I have to get some pieces parts that a certain incompetent mechanic never put back... (I know who the guy is, and if I could find him, I'd smack him...)
"Would you go with me, if we roll down streets of fire?
Would you hold on to me tighter, as the summer sun got higher?
If we roll from town to town, and never shut it down?"
-Excerpt from "Would You Go With Me", by Josh Turner
"What sucks about this is the only way to do it without spending a large amount of $$ is to spend time at the junkyard removing IAC's and comparing them to yours."
Not really.
GM has only used 2 different IAC pintle designs. The one he has is a straight taper and is used on all Manual trans cars.
All the Autos have the multi-angle, flatter design you are describing.
So he would just get the Auto version for the same year.
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Not really.
GM has only used 2 different IAC pintle designs. The one he has is a straight taper and is used on all Manual trans cars.
All the Autos have the multi-angle, flatter design you are describing.
Interesting. I've never heard this before. Is this in regards to a specific engine family? I've got quite a few different IAC motors with visibly different pintles. I suppose I've never measured the pintle tapers, but beginning and ending diameters are different across different families.
-->Slow
If you look into the aftermarket for replacement IACs you will find the whole lot of them boils down to only a few different part #s for all of the GM ones from the early 80's till the mid 90's. After that I haven't paid attention.
Of those years that I am speaking you will only find 2 different ones for most of the applications,,, a Manual trans version with a straight taper (one angle), and an Auto trans one with multiple angles.
GM did release many different part #s for all the different engines and I'm sure they are all different in some way. But the aftermarket always seems to boil it down to just 2 depending on the connector vintage.
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