In light of some of the recent posts I thought I'd share some experience I've had.

Several weeks ago I was involved in tuning a TBI car. 350, holley 670, 214i/220e @ .050, headers, 747 ECM, etc.

The baseline run was with aftermarket PROM H. I observed a gross rich condition and an unstable idle. 108/108 INT and BLM in closed loop. The exhaust burned your eyes on cold startup. This is a PROM that was supposed to be perfect for this combo.

We had to ditch PROM H due to an unforntunate development and start from a stock bin. After some effort, we were able to lean out the fuel MAP and get the idle much more stable.

Now, this engine we were working on is not radical. It idles around 750rpms @ 40kpa. The point I want to make is that stock proms and aftermarket proms are not going to get the job done. If you want your hotrod TBI engine to run right get the prom burning stuff and do it. Its not difficult, it just takes patience.

 

HE double hockey stix...YEAH!
Doing your own eproms is the only way to go.
Question, do you have a scanner or what? If it's running so rich, what injectors did you have? When I first started my 350, we had the TPS sensor hooked up backwards (WOT at idle and vice versa). Also play with the timing (with custom eprom in). The best part about a custom prom is the ability to adjust the timing. You can set your base to like 4 (good for starting and idle) and then just have a longer advance .

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, Jon (350 TBI!)
91 Red My website

 

Yes, we used a scan tool. The injectors are holley 65lbs/hr units at max fuel pressure.

[This message has been edited by Brent (edited June 06, 2001).]

 

he he he...

Brent is right. You need to get it done specifically to your car if you want it right. So far mine's doing good after some custom work. The idle takes a little to settle down, but I think it's that sucky cyberdyne speedo box. The Dakota Digital one is on order. I need to learn this PROM stuff for my 383 10 second TBI formula .

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88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
T56 - SIX-speed
open 3.73's
2 1/4 stock catback
I love pissing those LS1's off
My Formula

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