DFI vs FAST ?

[G McCall]

Will FAST cure my problem ?
Currently have DFI on my 86 T.
I am not happy at all with the street manners, as car is very cold natured (I usually have to help car stay running for a few minutes on start up and it slightly surges and even seems to slightly miss at cruise. Car accelerates fine, but I have not gone back to the track with this setup for a real test.Car has been tuned and retuned. Is this normal for my setup ? Will FAST cure these symtoms ?.


CAR has PT72 with 72lb injectors,BG intake, M&A heads, No EGR, ATR 4 bolt headers, Precision front mount, big roller cam and rockers, J&Es, all on original block. Built 200-4R with nonloc 3800+ stall.

 

[Reginald West]

I don't think your going to solve your problem by switching to a FAST uint. Your combo of parts is real close to my T Type set up.I use a dfi and I don't have the warm up problem that you discribe.In fact I can start my car and just drive away with no problems.I think your problem is in the after start enrichment table or one of the sensor inputs.

The reason I don't think the FAST unit will solve your problem is I just made this switch on my GN.I had a starting problem before the switch and I still had it afterwards.It turned out to be the interupter ring on the crank and the crank trigger.Even after I fixed the problem I had to take the car to the dyno to get it tuned right.The first thing the tuner noticed was that the computer was not reading the 02 sensor. Needless to say that ended the tuning session unit the fast unit was repaired.After the repairs were completed I returned to the dyno and the tunner made alot of adjustments to the unit and now the car runs good,starts fine and idles at 800 rpms.The dyno paid off for me I would still be chasing that problem with 02 sensor if not for tunner.

Bottom line check all your sensors and get someone who knows how to tune a DFI, it will work if its tuned right. I had Ken Duttwieler set up DFI for my T Type and I have never had a problem with it.

REG

 

[G McCall]

Reg,
With your DFI do you have the cruising characteristics I described ?.
I could live with the start up, although I will not, but the slight irregular surge and engine miss under cruise is not acceptable.

BTW
Thanks for the reply.

 

[Reginald West]

No I don't have that surge problem car runs nice and smooth at any speed.I have to think its in the tune somewhere.


REG

 

[G McCall]

Okay,
I'm taking it back to the tuner. He should be able to find the problem. I was afraid the combo was to much to expect street driveabilty.

 

[Reginald West]

My GN with the DFI had full ported M&A heads,83 lbs injectors, 80 4 bolt turbo, 70mm throttle body and everything else under the sun on it and it did not do what you discribed. TAKE IT BACK and tell him to get it right.

REG

 

[50Bucket]

Is this a Gen VI or Gen VII, I imagine its a Gen VI...??? I dont think you are gonna see any diff between the Gen VI and FAST, the FAST is basically a copy of the Gen VI with a few more bells and whistles....
If you paid a tuner to tune it though, dont leave until its done to your liking, you paid, if your not happy with it, its not the fuel injection system, its the tuner/calibration they did for you...

 

[Craig Smith]

Originally posted by 50Bucket
I dont think you are gonna see any diff between the Gen VI and FAST, the FAST is basically a copy of the Gen VI with a few more bells and whistles....

I've read in other posts where you have said it yourself that you don't have any tuning experience with these systems. On what experience or knowledge do you base this statement? It is clear to me that you don't know what you are talking about.

You sure are gangbusters to send people to Duttweiler or Spetter for a Gen 7 system, but you don't really seem to offer much else to this forum. If you don't have anything else to offer other than a sales pitch for these guys, be my guest. But don't tell people stuff about my product that isn't true.

 

[Otto J]

i have had both gen6 and now have a FAST, There is way more features besides bells and whistles that make it much more user friendly. And if you have a brain(not saying that toward anyone) at all and understand how an engine works you dont have to pay top dollar to have someone else tune you car everytime you make changes. I would not give up this system! I just talked to a buddy who had his saleen tuned in NJ, he paid $720 to have his car tuned without a dyno! Just using an air fuel meter to be sure car was running at top form. (which it is) but 720!! I can barely get people to pay that much to rebuild a performance transmission.
Otto

 

[50Bucket]

You are correct, I am not a pro tuner or anything close...I have looked into the history of the products though, there is a common ground between the two that I am sure you are aware of....The Gen VI came out, then shortly later after certain people were shuffled around or let go, the Speed Pro came out...
I am not here to start email battles or anything of the sort, starting from a clean slate though is a bit different then what happened here...

 

[JDEstill]

Whether or not some of the same people were involved in the creation of both programs is immaterial...

If you understand how they work you would see that there are some really basic fundamental differences between the two. FAST works very differently from the gen VI DFI.

John

 

[Craig Smith]

Your "research" on the history of these products sure has left you with a pretty skewed perspective on things.

It's correct that the designers of the FAST system first worked at DFI. That isn't news to anyone. If you think that means that our system was just a modified copy of theirs, you are way off base. I'm sure you've been in contact with some people that would want to give that impression, but it simply isn't the case. I am very familiar with the Gen 6 and my system and they are VERY different animals in every single aspect.

I'll ask you again to limit comments of this type about my product to things you know, not rumors you are trying to propagate. This forum (particularly those who regularly contribute to it) has developed a reputation nationwide as one of the best places for finding good information on aftermarket EFI systems from ANY manufacturer. You seem to favor DFI over FAST, and that's fine. There are plenty of people here who do. It would be nice if you would help us maintain that reputation by not resorting to spreading unfounded rumors about the "other guy's" product. Seems to me that Gewroo came out of the mothballs to bust you a few weeks ago for saying stuff like this.

 

[gewroo]

Yes I did Craig.

50Bucket, if you can't find anything better to do than take jabs at FAST and recite Turbo People's phone number, please find another forum. Craig does a lot to help our members and he shouldn't have to be put on the defensive against this sort of thing. If you have a legitimate problem with FAST, call them or even post it here. I'm sure you'll get help either way.

 

[bruce]

Originally posted by Craig Smith

It's correct that the designers of the FAST system first worked at DFI. That isn't news to anyone. If you think that means that our system was just a modified copy of theirs, you are way off base.

I am very familiar with the Gen 6 and my system and they are VERY different animals in every single aspect.

Well, without meaning to step on any toes, and just being the curious type that I am, what exactly are some of the differences?.

I'd like to hear any real differences involving any ecm. While details may differ, ie processor speed or language, what can really be new?.

 

[JrTuner]

Any person who has installed, used and tuned both systems would know that they are completely different. First off the Gen6 had an 8 bit processor and the FAST uses a 32 bit processor. Which in simple math terms means it is 4 times faster. The FAST has 8 injector drivers, the Gen 6 has 4 which means better fuel control especially with large injectors. The FAST is true speed density where as the Gen 6 is a look up table system. Theses are just the major points, the list goes on and on. From the tuning aspect the FAST software is far easier to use than the Gen 6 software and there is nothing on a Gen 6 that compares to the wide band O2 in the FAST system. Don't get me wrong the the Gen 6 was a good unit when it came out and in its time but technology changes fast these days and it fell behind. It is not actually fair to compare the Gen 6 with a FAST. They are not int he same league. It would be a fairer comparison to compare the Gen 7 and the FAST but we all know what can happen there.

 

[bruce]

Originally posted by JrTuner
The FAST is true speed density where as the Gen 6 is a look up table system.

The F.A.S.T. system doesn't use a look up table?.
Somehow I can't picture how that would work without using a WB. How would it have any AFR to cal'c to?.

On the 8 to 32 bit, why would that even matter?. There are enough mechanical hardware pieces on the fuel end to negate any .000000xxx change difference in calcs, it would seem anyway. While the EPA has tightened the screws on the oems that they HAVE to be able to do an injector PW recalculation while the injector is firing, why would that be a concern for mere mortals?.

I just fail to see any real advantage or need for faster then a 1Mhz processor.

I'm not trying to be obtuse, I just would really like to see the light on some of the whys folks talk about.

Given the in cylinder variances from chamber to chamber, and event to event, the world just seems to be a less then perfect place anyway.

 

[JrTuner]

I am not going to get in a pissing match with you. You obviously don't have much experience with programable engine management systems. All I can say is tune your car with a Gen 6 and then with a FAST. You will see the differences.

 

[bruce]

Originally posted by JrTuner
I am not going to get in a pissing match with you. You obviously don't have much experience with programable engine management systems. All I can say is tune your car with a Gen 6 and then with a FAST. You will see the differences.

So in other words rather then really answer any specific guestions you get in a ruffle, and walk away.

If you would care to point out one item that I was piss'y with, I'll gladly rephrase it for you.

BTW, I have a GM ecm that I'm running my (granted I had help) own code in so I do have a little experience in what it really takes to put together an EFI, that works.

So while I'm not a college grad., I do work at self educating myself, I was just asking guestions, and mentioning things that I had found. Some how I just thought that was the purpose of this list, ie being educational and informative.

 

[JDEstill]

bruce, in a nutshell, as I understand things:

DFI VI: reads MAP and rpm, looks up injector pw from a table. Has some limited means of correcting for MAT. Has a narrow band O2 option available (I think?)

FAST: reads MAP, rpm, MAT (and calculates air density in the intake manifold from those items); looks up VE and desired a/f ratio from tables; calculates required injector pw based on the above plus engine displacement, injector size, number of cylinders. The wide band O2 option allows the actual a/f ratio to be controlled to the desired (user input) a/f ratio.

John

 

[bruce]

Originally posted by JDEstill
bruce, in a nutshell, as I understand things:
DFI VI: reads MAP and rpm, looks up injector pw from a table. Has some limited means of correcting for MAT. Has a narrow band O2 option available (I think?)
FAST: reads MAP, rpm, MAT (and calculates air density in the intake manifold from those items); looks up VE and desired a/f ratio from tables; calculates required injector pw based on the above plus engine displacement, injector size, number of cylinders. The wide band O2 option allows the actual a/f ratio to be controlled to the desired (user input) a/f ratio.

I'd imagine they also look at Coolant temp..
Even if the F.A.S.T. does all that you mention to include CTS.

Then both still miss some of the features of the oem one. The 1227148 also looks at run time, and uses a few corrections for timing and fuel based on run time. Which in my opinion do seem to help.

While originally the aftermarkets all claimed to be simple to program, and still work on being user friendly, they have been getting more complex to be able to get really nice drivibility.

While the aftermarkets keep coming back with this faster processor rate, I just wonder if it's an attempt to get the best drivibility with the min amount of actual tuning. ie being user friendly by not using run time compensations, and other tweakable items.

It sure would be interesting to run a 8 channel data logging system on one given car, then swap ecms around. Till then or someone actually says what their product does (and how), we'll all just be at the mercy of the PR folks.

Golly, I think I have this worded well enough no one will see it as flame bait, trolling or anything else then a desire for knowing the truth.