RAGEman

iTrader: (4)

Hi, folks. I just installed a ported & polished throttle body. With the A/C off, the idle is all out of whack. For example, when taking off from a stop in 1st gear, upon letting off the throttle completely at around 1700 RPM and disengaging the clutch, the idle does not return down to normal (1000 RPM or less), instead it either hangs or might even increase (up to 2000 RPM or so). Same when coming to a stop. Idle hangs and won't return to normal until vehicle speed has been at zero for a second or two. With A/C on, the idle behaves much better, but will still hang ever so slightly.

I've researched this somewhat and haven't found anything conclusive. Hopefully some of you PCM gurus will be able to offer some help. Thanks in advance.

[EDIT: At times, it does act up ever so slightly even with the A/C on, but it's still much worse with it off.]

Quickin

Iac?

..........................

RAGEman

iTrader: (4)

Yes, it stands for idle air control, and yes, my car has it. Thanks for your help. Anyone else have any abbreviations they need help with?

ringram

You need to tune the IAC activity with RAF, Cracker and Follower Im sure is what he means. Do some searching on those terms and all will be revealed.

AC ON changes the amount of IAC airflow which is why that fixes it.

RAGEman

iTrader: (4)

<sarcasm>You're right, I should have known that he meant I needed to tune the IAC activity with RAF, Cracker and Follower from just the abbreviation.</sarcasm>

Thank you for providing me with at least complete sentences in your response.

Have you ever seen this problem arise after merely installing a ported throttle body with no other changes?

Problem is, I don't have tuning software of any kind except the old Diablosport Predator. And I could be wrong, but I believe RAF, Cracker and Follower are out of its realm of tuning.

Frost

iTrader: (45)

Well damn you posted in the tuning section, not the bolt-ons section so this is what you get.

You need to get the the blade screw set properly. It is open too far right now. Since you have no scan tool, you will have to try and repeat until you get it right. FWIW you may not get it right without tuning.

RAGEman

iTrader: (4)

I don't think it's what I get at all. I think no matter which forum you post in, you should get complete sentences. If you're implying that I should post this in the external engine forum (since there is no "bolt-ons section"), I think you're absolutely right. I'll do so right now and link to this one.

So, you think the IAC is trying to compensate for the set screw being adjusted incorrectly? If that was it, upon resetting the PCM, wouldn't the idle immediately be too high upon cold startup?

Well, correct me if my mindset is all wrong here, but since I've done the exact same mod on my previous car ('01 Z28) with no problems at all, I don't think I should actually have to do any tuning to fix the problem.

Frost

iTrader: (45)

It's not a paid service and the people here people don't work for you. Your problems are focused around the IAC.

But to get to the point, it depends on a few factors, the port job being one of them. I just tuned a cammed car recently and had it near perfect. About 2 weekends later the guy decided to put on a ported TB. I spent about 2 more hours getting it adjusted and making some idle changes to get it right. Yes the IAC is compensating to bring down the idle. You adaptive idle routines go out of the window once the car is moving. That's why it won't settle down until you stop. If it were mine and I just couldn't find a good adjustment point based on the previous tune, I'd do an RAF assessment and likely end up modifying the throttle cracker table some.

Quickin

The IAC is your problem, thats why I told you check it out. Most people would have known that was implied by posting "IAC". And I don't mean "check it out" by just making sure someone didn't streal it off your engine. You go figure out why the "IAC" is fucked or not working properly. You didn't know "dick" before, now you have a starting point. This is what happens when people install mods that give them 2 hp and don't know what else may be affected when they do so.


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RAGEman

iTrader: (4)

I never said anyone worked for me. But, it's a little thing called common courtesy and being civil towards your fellow human beings. Something apparently not all people understand. Some people always want to condescend to others whenever possible, even on an internet bulletin board, I suppose because it makes them feel better about themselves.

Well, I might check that out at some point in the future, but the more I think about it, the more I'd like to stay away from modifying the tune (if it can possibly be avoided) mainly because I can't afford tuning software yet. But, also, as I may (or may not) have mentioned, I had an '01 Z28 with the exact same mod that never had this issue. So, I appreciate your help and that of the others that did offer help, and I'll probably focus more on the thread in external engine now. Thanks again.

RAGEman

iTrader: (4)

You never told me to check it out.

It's true that most people may have known what you meant, but they shouldn't have had to guess. If you don't want to help or think you're too good, then don't help. You don't have to come in here and act like you're all-knowing just to give your self-esteem a boost. No one forced you to go through all that effort. After all, it's just the Internet. Your ***** doesn't get any bigger by attempting to make someone look less intelligent than you on an Internet BB.

For one thing, this exact mod showed an increase of 9 RWHP based on three-pull averages before and after on my '01. Not to mention the benefit of the bump stop mod, allowing full-throttle. Not bad for a very inexpensive mod. This is what happens when you assume you know someone based off a single Internet post: you reveal your stupidity.