Fuel injection? Open or Closed loop?

[art leong]

Originally Posted by HawkBrosMav

you guys might want to read the rulebook....

FUEL INJECTION
Fuel injection must retain OEM throttle body(s), plenum, and
manifold. If OEM throttle body(s) was equipped with electronic
throttle control (i.e., drive by wire), the throttle body(s) may be
adapted to mechanical throttle linkage if an aftermarket OEM-type
electronic-fuel-injection system is used. Larger fuel injectors
permitted, provided no modification or redrilling of manifolds is
performed. Electronic fuel injection must be closed, OEM-type
system; i.e., may monitor only engine functions. Monitoring of
vehicle performance criteria, wheel speed, driveshaft speed,
vehicle acceleration, etc. by fuel-injection system prohibited. All
aftermarket OEM-type electronic fuel injection must be NHRAaccepted. A current list of NHRA-accepted electronic-fuel-injection
systems is available on NHRARacer.com. Open-loop systems
permitted on production vehicles as equipped with OEM electronic
fuel injection. See General Regulations 9:1.

not saying it could be checked very easily but 99% of you are illegal running in open loop..

Brad

Some stock systems run in open loop. Till certain parameters are met. The turbododges are in open loop at wide open throttle.
We are not illegal. I had went through an NHRA electronics teardown. And they had asked it I running open loop.

[boostedf22c]

Open loop.

Unless you have an o2 sensor for each cylinder (with correction factors to support each cylinder) then you could argue some advantages to running it closed loop.

[Bobby Fazio]

Open loop is probably better for bracket racing consistency I would think because the car doesn't adjust itself going down track.. however, would closed loop be better in a heads up run or when you need that extra power if the car is properly tuning itself downtrack? Has anyone ever tested to see which method was strictly quicker?

[art leong]

Originally Posted by SStock1373

Open loop is probably better for bracket racing consistency I would think because the car doesn't adjust itself going down track.. however, would closed loop be better in a heads up run or when you need that extra power if the car is properly tuning itself downtrack? Has anyone ever tested to see which method was strictly quicker?

I'm no expert tuner. But I would be cautious using closed loop to go faster. I don't think the O2 sensors most of us use are fast reading enough. I have changed brands of O2 sensors and seen a difference, when tuning off the datalogger.

[Ed Wright]

Art is right.

[boster]

In my opinion the tuner should always have full control of the fuel map and timing .

But on the new cars from the factory the oem computer controls everthing . If its oem the the computer can control the car down track and its more consistenbut not faster . NHRA has allowed both , but if its a aftermarket computer the computer is not allowed to make changes going down the track unless the car came with a computer that did .

I like were I have full control of the car bracket mode or heads up . I vote open loop

[Ed Wright]

Unless the new Fords are different, from the factory they all go to open loop in P.E. (Power Enrichment) mode, or wide open throttle.

[DrHP]

Gentlemen,

The question of closed or open loop is not really valid when the engine is using a narrow band O2 sensor. The stock systems normally use this narrow band sensor that is accurate only in a very narrow target area of about stoichiometric (14.68:1 with pump gasolne).The wide band sensors can be used with the appropriate control system, but I would think you want absolute control to be consistanrt. Some of you racers hit it on the head, mentioning that at WOT the system had better be in open loop, using the base fuel tables with its modifiers. The operational parameters regardng PE and the closed loop threshold are probably the areas that are highly tuned (along with base fuel and spark), that the successful guys paying attention to. Forced open loop would cerntainly be my choice!

Just an old racers two cents, Dennis Baccus
Former F/S record holder - 1969 Z28,
Current calibration engineer on GM MEFI systems and engine builder

[Rob Lloyd]

Originally Posted by art leong

Some stock systems run in open loop. Till certain parameters are met. The turbododges are in open loop at wide open throttle.
We are not illegal. I had went through an NHRA electronics teardown. And they had asked it I running open loop.

There's an electronics teardown? I never heard that one before. Was this in stock with a TD or with the Neon?

[art leong]

Originally Posted by Rob Lloyd

There's an electronics teardown? I never heard that one before. Was this in stock with a TD or with the Neon?

This was with the Neon. Jake Hairston did it at Englishtown in 2010. It took about 1 1/2 hours. They wanted me to connect my laptop to it to show the program. He wrote some stuff down, serial numbers etc..And traced all wiring. Which in my case gave them fits.
But I passed.