If I were to purchase a DFI system that has everything you could ever need, except Idle Speed Control, would it be possible to build my own controller? If I am not mistaken, the idle air controller gives the engine more air while the engine is warming up. If this is the correct operation, would there be any way to interface the engine temp sensor with the idle air control valve so it operated independently of the ECM? The reason I ask is because I have found an advanced DFI system for sale for a good price, but it does not include IAC becuase it was designed for race cars. That seems to be the only feature missing that I will need to operate the car on the street. Thanks for the help.

 

You might want to post this over on the diy_eprom or dfi board. Most race car systems won't work well on the street. They're usually are missing a few things. The most street friendly systems are MAF (early TPI) then speed density (only use MAP) then true race car systems using alpha-n which only have a fuel curve depending on engine rpm. They don't take into consideration the engine load. Now if you've got a 2000lb car and a 600+hp engine you could probably make it pretty darn streetable since minimal engine load. Just trying to save you some big bucks. The best street units I think are the stock GM ecms. They have TONS of features that only the expensive aftermarket systems have! They're digital with eproms (not analog like Holley pro-jection) and most have been hacked to death. Definatly do some more research before you jump into just trying to build a stepper motor control for your IAC. BTW, even if you got the IAC to open by controlling it from a dash ****...you'll be running lean (IAC is a vacuum leak). For the street I don't see any obvious reasons to get rid of a GM ecm. Especially now that the speed density TPI ecm can use a flash prom!!! Give me ONE reason why dfi would be better for the street.

 

Thanks for the info. The system in question does use a MAP sensor for sensing engine load. Here is a link to the site for the DFI system: http://www.dtafast.co.uk/ecuspec.htm The system being considered is the E8. I found a guy that is selling one fairly cheap, and I would like to try it out.

I have a few reasons behind my choice for DFI over an ECM.

1. Because I dont want to burn chips.
2. I will possibly add a turbocharger in the future, and I would like my fuel injection system to be ready to accept changes easily.
3. I am a computer geek, and I just gotta be able to hook a laptop up to my car to change params




[This message has been edited by Scott_92RS (edited October 31, 2001).]

 

Hehe that's pretty funny!

1. Burning chips is a piece of cake !! I takes me 15 seconds to burn one.

2. TPI or TBI is ALWAYS ready for upgrades. All you have to do is redesign the fuel curves !

3. You CAN plug in a laptop and modify the params on the fly with an EPROM emulator!

So any other reasons ?

------------------
1991 Z28 5.7 TPI

ZZ4 heads, ZZ4 cam, Harland Sharp roller rockers, Accel base, SLP siamesed runners, 52MM SLP Throttle Body, Hooker Headers, Flowmaster catback, MSD6A ignition, Home made ramair system, aluminum driveshaft, WC 5-speed etc

 

1. I'm sure ANYONE can burn a chip in 15 seconds, now whether it runs right or not is a different story. We all know it takes MANY (possibly hundreds) of chips to get your setup even close to optimal.

2. Nothing to say about that one.

3. The emulators still have issues and don't always work.

 

Then use a 7749. It already has a wastegate control output. Hell there's even a couple people running the 7749 code in a 7730 ECM.

Besides, building a seperate IAC motor control kinda takes away from that "hook up a laptop and go" aspect, doesn't it?