my 454 swap

[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+.

[EagleMark]

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+.

That usually means it is in ALDL mode, idle RPM is set to 1000. I beleive it also changes spark too...

The 350 prom is just totally differant then a 454 prom.

Like I said above the 454 chip you have is open loop idle and been updated twice. The 350 prom is idling correctly because it's a closed loop idle prom.

[black dawg]

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.

[1project2many]

Swapped in a 74 454 that I added a stock vortec cam to.

Cam from 96 or newer engine? Did you add roller lifters as well?

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 ........

Because some scanners use "10k" or "ALDL mode" which enables different settings in the calibration for testing and diagnosis.

Old trick for setting minimum air is to cut a strip of paper 1/4" wide then close between throttle plate and bore at 90 deg to shaft. Proper setting gives slight drag when paper is pulled out. Do when engine is warm for best results.

[black dawg]

Used retrofit rollers and the gen 6 timing set and cam retainer.

[JeepsAndGuns]

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.

If the 454 bin you have has been superceded twice, and the 350 bin you have runs significantly better, then I (just me personally) would tune that bin.
Just my $0.02 worth.

[EagleMark]

I'd agree with JeepsandGuns if that was the only 2 bins I had. But we have plenty of 454 bins to start with including the AZFT it was superceeded to.

Yes you can make that a Closed Loop Idle bin but then it has been superceeded twice, so I'd still start with a differant one like the AZFT it was superceeded to.

I've also used the AZFT a few times for a starter tune and had no issues.

[black dawg]

Well, I got the 454 prom to work for me. It seems my balancer has slipped, so timing was way to advanced. I also lowered my fuel psi from 15 to 12 and this leaned it out to where it works. I think these injectors are to sloppy, because I have never seen that little of pressure change affect the o2 as much as this did. The injectors do look drippy at cold start.

what would you expect to see for warmed up open loop idle o2 readings at 3500ft? I am .89ish
what would you expect for WOT? I get from .96-1.0

[gregs78cam]

Well in a TBI dropping from 15 to 12 psi is about a 10% difference in flow. I would think an OL idle should be close to .50 maybe .60, ideally .45, but that will depend on your VE table. 0.89V at idle sounds really rich. .96 - 1.0 at WOT sounds only slightly rich, but a NBO2 is not even close to being useful for WOT tuning IMHO.

[EagleMark]

Well, I got the 454 prom to work for me. It seems my balancer has slipped, so timing was way to advanced. I also lowered my fuel psi from 15 to 12 and this leaned it out to where it works. I think these injectors are to sloppy, because I have never seen that little of pressure change affect the o2 as much as this did. The injectors do look drippy at cold start.

what would you expect to see for warmed up open loop idle o2 readings at 3500ft? I am .89ish
what would you expect for WOT? I get from .96-1.0

3 psi is not a lot on MPFI when base pressure is 43.5 but 3 psi is a lot on a TBI system based on 13 psi.

The O2 readings your showing are rich, but at 3500 feet I would expect that.

Narrow Band O2 sensor is only measuring 1 volt and designed to be about .45 for 14.7 to 1 AFR so higher is richer and lower is leaner. But it is only accurate around .45 and ECM keeps it swinging back and forth there.

Wide Band O2 sensor uses 0 to 5 volts so it is 5 times more accurate and designed to measure AFR, not just keep it at 14.7 to 1.

Having these old injectors serviced is great money spent. If you don't have someone local look for Mr Injector. I've seen between 5 and 13% difference in injector flow rates from service.

With the cam change your only option for great running engine is a chip tune. If you don't have equiptment needed, then you've really done all you can. You need to get these mechanical issues in order before tuning anyway. If you want to get into tuning then buy equiptment and spend some time. If you don't want to spend time and money then buy a cable to record data and you can buy a tuned chip. Either option is about $150. to do it right.