my 454 swap

[black dawg]

Swapped in a 74 454 that I added a stock vortec cam to.
Using 92 454 throttle body. computer is 7747 prom is ANTY, but is a hypertec. I got the number for the prom using my scan tool.

The problem is the idle speed ends up at 1000-1100. I do the whole min set procedure, my book tells me 700 in gear. When I finish the procedure and restart idle speed is slightly higher than min, with IAC counts in the 35-40 range. A few restarts later, the idle creeps (1000-1100) up even though IAC is at 0. And it is completely seated. There are no vac leaks and I have tried backing the timing down from 4 deg and it doesnt really help.

[JeepsAndGuns]

If the IAC goes to zero counts, then it sounds like the throttle blades are too far open. They usally wont do this untill engine is warm. I did this when I was new to tuning. I guess I had set the min idle when the engine was not warm enough. As for a long time I couldnt get it to go to 650 rpm idle like I had set, I then noticed my iac was at zero! Reset my min idle and all was well after that.

[EagleMark]

ANTY has a flat 750 RPM idle for all temps in "IAC - Desired C/L Idle Speed" I didn't look for any other changes.

To do the Min Air set procedure motor has to be totally warmed up even rev the engine after warmed up for a minute if you can't drive it. Then has to be in Closed Loop. If your getting 0 IAC counts and 1000 RPM with no vacuum leaks then the throttle blades are open to far.

Also ANTY has been superceeded twice, once to ATPX, then to final version of AZFT. I don't know why it was updated by GM but it may have issues, twice!

[black dawg]

well I will wait till the exhaust is done up before I mess with it anymore. The o2 is fresh and is the same one I used with the 350. Thanks for the replies

[EagleMark]

Just looked at that bin some more and it is an Open Loop idle bin. Will have to make some changes to be closed loop idle...

[Nasty-Z]

Check the throttle shaft play in the TBI , the BBC TBI's are notorious for elongating the holes the throttle shaft rides through , causing the exact problem you describe.

As others have said , if the IAC counts are at zero , un metered air is entering somewhere or the throttle blades have been opened up too far .

Does it do the idle creep with and without your scan tool hooked up to the ALDL port , some of the different scan tools I have come across would cause an idle creep if left hooked up to monitor data , never could really explain it ........

TOM

[black dawg]

Check the throttle shaft play in the TBI , the BBC TBI's are notorious for elongating the holes the throttle shaft rides through , causing the exact problem you describe.

As others have said , if the IAC counts are at zero , un metered air is entering somewhere or the throttle blades have been opened up too far .

Does it do the idle creep with and without your scan tool hooked up to the ALDL port , some of the different scan tools I have come across would cause an idle creep if left hooked up to monitor data , never could really explain it ........

TOM

The scan tool does have a small effect on it. I have seen that on some of the tbi stuff where with the scan tool connected they idle 1000+.

[black dawg]

Well as an experiment I put my 350 prom in to see what the idle will do, and it works just like it should.

I drove it some with the 350 prom, and there was some very slight lean sags till the block learn crept up, and after that it runs very good. wot is actually richer with the 350 prom (.960 vs .900)

What is the range of blm, the 454 prom while driving runs about 140-160 blm, and the 350 prom runs 150-180.

[black dawg]

Also ANTY has been superceeded twice, once to ATPX, then to final version of AZFT. I don't know why it was updated by GM but it may have issues, twice!

I have gotten this thing mostly sorted, (no tuning yet) but I am curious if the issues I am having is because of this prom. The prom I have is anty, and has been modified by hypertec before I bought it used.

What would it cost me to get somebody to burn me an updated or better stock prom for this thing. I have decided that I wont be happy with this thing without some tuning being done, but hate to start with this prom if it is a pos.

[EagleMark]

would it be better to tune on the 454 chip? can it be made closed loop idle? Or would it be easier to just make the 350 chip match the 454 engine.

You can, I use ASDU and make it a 7.4L

What is the other smaller removable chip in the 7747 for?

Netres, is it correct for your 7.4L?

Do you think it could need that much fuel pressure because of the engine mods and a stock prom? I am not finding anything wrong.

No something is wrong.

I have gotten this thing mostly sorted, (no tuning yet) but I am curious if the issues I am having is because of this prom. The prom I have is anty, and has been modified by hypertec before I bought it used.

What would it cost me to get somebody to burn me an updated or better stock prom for this thing. I have decided that I wont be happy with this thing without some tuning being done, but hate to start with this prom if it is a pos.

Post a data log so I can see what it is doing?

[black dawg]

On the netres chip, how do I tell? Does it matter?

On the fuel pressure, I dont believe my gauge, but adjusted fuel pressure to where blm is reasonable. gauge shows 22psi and wont hardly run below about 17 psi.

Not set up to data log at this point.

What I would like to do is get a better prom, and then if it still isnt satisfactory, I am hoping the better prom is is closer/easier to tune for somebody.

[EagleMark]

Is the netres chip the one that came in ECM with the truck?

I can tune whatever is needed and start with a better PROM, but without data logs it's just an educated guess, not a tune!

You really need to figure out what the fuel pressure is. If the motor is stock and the injectors are correct BB then 13-14 psi is GOOOD! 12 is OK...

How far in Montana are you from Coeur d'Alene Idaho?