Just fired this thing up for the first time last night, what a great feeling since I wasn't sure if this was going to work. This truck went from a crappy propane powered 350 to this

http://www.youtube.com/watch?v=9esrJkyf7b8


-stock manual 454 .bin from diy-efi ftp site
-turned off egr other unnecessaries, changed BPW to 90 from 134 to match injector sizes
-1227747 ecm with modified injector driver by running 2 factory sense resistors in parallel to obtain .05 ohm since no one seems to have those in stock
-the bigger of the 2 comp cams "TBI" camshafts
-patriot heads
some sort of headers that fit trucks with big blocks
-twin 350 TBI units with 350 injectors
-external FPR

 

Nice.

Do you have any pics of the dual TBI setup? I would love to see the linkage and fuel line routing. What intake manifold is on there?

What did you do with the IAC, and TPS? Just leave one of each?

I was just talking to someone the other day. For about 10 years people have talked about doing a dual TBI but this could be the first one I have seen actually run. (sorry to anyone else running 2 TBIs I have not been around here in a while)

 

I'll try to take some tomorrow, I avoided shots of it because the harness was partially unloomed and looked bad enough that I'd give someone else crap for it if they posted a pic of a harness in that condition. The intake is edelbrock oval port, oval port heads too. 1 TPS, 1 IAC. The intake has cast in runners that connect the rear 4 and front 4 intake runners so vacuum should be consistant enough for the 1 IAC to work.

Its not my truck, I just handled the fuel injection. It belongs to a friend of mine who is taking it to Top Truck Challenge next week.

It still lacks exhaust, so I haven't put a wideband on it yet but I already know the BPW needs to be lowered. You can probably see it in this video (http://www.youtube.com/watch?v=8DcvL...eature=channel) the rear 2 header tubes were glowing red. These were junkyard TBI's that I'm thinking were not 62.5 pound injectors. The injectors were crusty enough to not have any visible part #'s so we replaced them with 4 new ones today. It was so rich with the new injectors that it would not start unless 2 of the injectors were unplugged.

I'm going to mess with it some more tomorrow morning, its been a long day. The chassis wiring was REALLY bad so I spent all day redoing that instead of important fun things like EFI tuning.

 

well I lied, no pictures. Was too busy getting the neverending list of things to do finished. Got the exhaust ran, messed with the wideband and made quick and dirty fuel and idle speed changes. Shagged *** around the block in it then strapped it on a trailer for its trip to Hollister Hills.

I hope it survives the week, I really want to get a deadline free chance to do all of the things I should have done Little things like oscope the PNH driver and see if the modification is really doing what I think it should do. I figure it drives and idles fine and has no problem hitting 6500RPM so something must be right.

attached the .bin

 

I had always wondered how the part throttle would be on a setup like that. I was thinking about doing that on a sbc. Seems like the tip in from idle and the low RPM would be a little tricky. Almost like having 4 giant primaries. It is probably way better on a big block like that. Doesnt look like street manners are really an issue on that truck anyway. I guess the injector driver issue probably kept these from being more common.
Very Cool for sure.

 

Thanks for the compliments.

Another one of my friends is putting together a 76 4x4 ford pickup short bed street cruiser, sort of an 80's riffic theme with double hoop chrome rollbar and all the cheeseball junk. We're talking about putting it on the 360. I think it would really fit the theme of that truck as far as looks go, and should look better than the really ugly wire harness I'm refusing to show you guys. If that goes down it will be the real test for driveability on this setup.

 

and here it is with an ignition miss. Those plug boots are way close to the headers, I'm hoping thats the problem.

http://www.youtube.com/watch?v=Mb_QnCUTHTE

http://www.youtube.com/watch?v=yhgrsfFvkTY

 

Could you elaborate on that a little? I've been thinking about doing pretty much the same thing, except I'm considering using a proform 4150 carb base, and milling a block of aluminum into a 4bbl TBI.

-- Joe

 

sounds interesting. got anything drawn up? if so, feel like sharing .igs files?


this is from a 746 I had sitting around, but the circled resistors are the ones that need to be changed. I desoldered them from another 746 board I had sitting around (I have too much crap sitting around) and laid them out in parallel and soldered them to the existing resistors. 1/r1 + 1/r2 = 1/rt right?

 

Nothing drawn up, but will do.

My plan is to simply mill out of a block of aluminum a funnel with two stands for four TBI injectors, and an IAC passage in the rear.

The proform base plates have progressive linkage, so if the funnel is milled properly, all four injectors should provide fuel to the open 2 front blades during cruise and idle, and when WOT vac should pull the fuel directly down all 4 blades.


So basically, you split the resistance in half ? So stock those are .10 ohm each, and you needed .05 ohm each to drive the additional injectors?

-- Joe

 

yes, stacking the resistors will allow twice the current to flow before current limiting.

Joe, what about starting with a tall 4 hole spacer, and machining it to what you want? might save you some time?

and for an IAC, I chopped a cavity from a 2.8L throttle body lower half, and it makes a cool flat-mounted external IAC without all the machine work for the seat and threads. I'll see if I can find a picture of it from this site or local here. I never did anything with it, but I have it ready when I ever do.

here is the thread:
https://www.thirdgen.org/forums/diy-...ive-found.html

posts 48-50 I added some pics of the IAC housing.

 

i think fast 355 was saying you should stay of rinning only one IAC on a dual tbi due to uneven fuel distribution. this makes sense, but good luck!

 

Q: My plan is to simply mill out of a block of aluminum a funnel with two stands for four TBI injectors, and an IAC passage in the rear.

The proform base plates have progressive linkage, so if the funnel is milled properly, all four injectors should provide fuel to the open 2 front blades during cruise and idle, and when WOT vac should pull the fuel directly down all 4 blades.

I see you are cold climate. any plans to add a coolant passage since you are creating a custom TB?

 

No. I've always run aftermarket throttle bodies on my single plane intakes with no coolant ports. I also put my car away for the winter at the end of October. By November, shoe shoes go on the horses and they are my winter fun.

Keep in mind, I also run open loop. Not daily drivers by any stretch.

-- Joe

 

Well its back and time to get it running right.

I remember seeing an entry for minimum injector pulse width in the ECM tables, but I cannot find any documentation for it now that its a concern. Does anyone know the practical min PW for a TBI setup?

I threw a quick excel sheet together to identify trouble areas if a min PW exists, I realize injectors are not state devices so I'm expecting so I'm trying to work around it.

Do the tables affected by the min bpw look like trouble spots that would cause hard starting and rich idle?

attachment isn't working

download it here
http://www.flemcodesign.com/sites/de.../FuelTable.xls

 

I suspect min PW(idle) may be related to injector size and lesser extent fuel pressure. I know my 80 lbs injectors at 20 lbs FP had difficulty at under 1.8 msec I recall in closed loop. You can work around that in the tune.

 

I thought peak and hold injectors solved that low pulsewidth issue?

-- Joe

 

Please elaborate. I am refering to GM TBI 80 lb rated injectors. I thought all TBI injectors are the same on how they function. I only read P & H for port injs?

 

Port injectors, at least on TPI applications, are saturated injectors.

TBI should be peak and hold. No?

-- Joe

 

TBI is peak and hold, thats the reason for the ECM modification above.


Does anyone know the actual strategy in determining pulse width for a 1227747? I tried following that ASDZ hack but didn't see anything that looked like the gas law, the air temp sensor is non existant, and the cylinder volume is stored as a function dependant on injector size.

 

The issue of max pulse width is discussed in the TBI sticky "come in free tune".

Min pulse width I believe is variable based upon injector size, manufacturer, and fuel pressure(VAFPR vs constant FP), voltage. Others not sure.

Back to my post. When I ran 7747 with constant FP at 20 and 80 lbs injectors I believe my idle got funky at 1.80(millisecs?). Now I run VAFPR so that changed that issue. As did running synch fuel only, OL idle, locked SA for idle, and IAT.

 

Joe, have you seen the unit I fabbed up:

https://www.thirdgen.org/forums/tbi/...anken-tbi.html

This one uses a Dominator size baseplate adapter. Unfortunately pressures at my business prevented it from going on my motor. I'm still interested in loaning it to someone to try out.

Paul T.

 

I assume you are not Simpson36. Have you seen his work?

 

I hadn't seen Simpson's stuff, I just looked at it, pretty nice, he seems to have specialized on on the cross-flow stuff.

Paul T.

 

I did the chip in the 4.3L Zuk Buggy that ran out there with you guys. I heard this thing sounded like a cannon when it got there, but straightened out? How'd it end up running overall?

I've thought about doing exactly what you did. Except I planned to use 2 ECMs and a progressive linkage. The 1st TB would be like primaries and run the full blown ECM with timing, etc. The 2nd would be like secondaries and run the 2nd ECM for fuel only off the 2nd TP sensor. That way you could have the secondary injectors almost shut off when only running on the primaries.

 

I didn't go out there, but I heard it was rough

I based most of it off of the stock 454 bins that were on diy-efi.org. Big mistake. I should have looked at the tables closer. They had VE of over 100% in some cells. No way an 80's big block did that. I blame the cannon sounds on way off VE tables, lack of a MAT, who knows what size injectors, and about a 2 hour window of having complete exhaust with an O2 bung and an LC1 that overheated in about 20 minutes.

It ran pretty well here in Texas, must be that California smog.


I've been digging through the 747 hack to find out why they would have done the VE tables this way and I don't like what I see. It seems to me that the 747 is more of a lookup table system than a true speed density system. I'm switching it to a 427 ecm and starting the tables from scratch with more reasonably expected numbers. Hopefully the stuff gets here by this weekend to do the swap.

Do you plan on only running open loop on your setup?

 

Do you anticipate any fuel dristribution issues? I would think a single plane manifold?

 

I don't know if I'll ever actually do it. It's just a thought that has been bouncing around in my head. I like the dual TB idea, but wanted to get around the throttle response issues.
As far as fuel distribution goes, I kind of thought about it like an old quadrajet in my head. With the primary TB open and the secondary shut, all 8 cylinders are pulling air and fuel though the primary TB (injectors above the throttle blades), The secondary injectors would be giving just enough fuel to mix with the vacuum leak created by the secondary throttle blades (like idle). So, it's not like there's air rushing in without fuel mixed in it to create a lean condition to the back cylinders.

It'd be a cool experiment. However, after watching Small Block Supermodifieds make 450 HP on a 2 barrel Holley last weekend, I'm doubting the need for a toilet on top of the motor.

 

I think the carb is much better than TBI on fuel distribution at idle on stock or mildly modified motors. My experience running two single TBI's on an XRam(plenum on top of single plane with top plate) was that 4 plugs were very rich and 4 were OK. I also had a large puddle in one corner of plenum. But that may have been the design of XRam rather than TBI deficiencies. the key on a wet system(TBI) is getting the manifold to be equally wet and avoid it being dry when VAC decreases(falls out suspension) or increases sharply(shearing fuel off internally). Every day I drive my car I slow down from 45 mph down a long hill and make a hard turn then slow to 25 and try to maintain that speed and I find I have no fuel in manifold to accelerate. It was sheared off under high VAC and then TB blades open and I lose VAC and air rushes in with inadequate fuel being delievered. I think a carb would better handle that.

 

Interesting.
Do you have DFCO enabled?

 

yes DFCO disabled. But I will double check. I believe in logs I see 5% DC during event. Maybe I maintain OL <28 mph? Currently <15. hyway also disabled BUT will enable it soon.

If I coast down to 20 and then nail it it runs real good(manual).

AE enrichment....

 

sweet, corrupt eprom and it was running in limp mode. That explains the crappyness. I knew I wasn't THAT big of a hack This is the first TBI conversion I've done that has crapped the eprom after I was "done" with it. I don't know how it happened, but I think I'm through with eprom, eeprom only from now on.

anyway, '427 is installed and its running. Tomorrow I'll start tuning after browsing through the $0D hack. The tunerpro def leaves a lot to be desired in the error code bits section.

 

Messed with it some more this week for the first time in a long time.

switched to a bosch 044 pump so that we can get good AN fittings to the -8 line.
got rid of the MSD garbage coil that I think was 90% of the problem in California (I've had more bad luck than good luck with MSD, they made me look bad at a highly covered event and I'm never touching their products again)
swapped to 4 50lb injectors
put a guestimated tune into the 427 ecm


in neutral it sounds great. Under load it gets a little rough, but I had driver problems with the ALDL cable that are now sorted out and I think the ostrich was unplugged when it started getting rough

Tomorrow I'll start logging and getting it better, but found that cyl #2 is completely dead. Owner will be building a stroker shortblock for it soon. In the mean time I'll be disabling closed loop and fattening up the fuel.

I need to study up on the stall saver stuff. If you wrap it up to 6g and let off it stumbles and dies. Do the percentages in tunerpro mean the % below target idle?

 

here is video of it on the '427
http://www.youtube.com/watch?v=gYSxbTpBCMQ