they say it cant be done....

Topic: they say it cant be done.... (Read 4321 times) previous topic - next topic

they say it cant be done....

Reply #15 – September 21, 2009, 09:52:39 PM

never thought of that. i am going to make the t-bird a purpose built drag car. i'm picking up a fox body mustang project to make my DD. stang will have an HO 5.0 with CFI induction and a t5 with 3.73 gears.

they say it cant be done....

Reply #16 – September 21, 2009, 10:52:56 PM

Quote from: danzajax;291933

If you add a vacuum container, it would probably have a negative effect on throttle response.

Being the 'proud owner' of TWO 3.8's with TBI's, and that silly little reservoir down near the MAP, I'll certify the throttle response issue. I've always noticed a slight lag from throttle change to actual response. (Not that I was expecting something neck breaking, just a response, please). I bought one of the two I have brand new in December '85, and from day dot, it's had that lag. Not a huge lag, but a lag, nonetheless. If you take the breather cover off and snap the throttle, it sort of sounds like a cat coughing up a fur ball, then it starts to wind up. If you snap it quick enough and let go, about all you get is some grumbling in the exhaust from the AIR when it dumps a load of air in there to take care of the unspent fuel the O2's just sniffed out. Little if any change in RPM. IMHO, that would be that little "filter" hard at work. EEC senses throttle position change and dumps the fuel in there, but the MAP doesn't really sense the quick drop in vacuum before it's restored. That's my theory, anyway. Maybe Ford was hiding something else on the 3.8?

I was used to instantaneous response from carbed engines with standard ignitions. There is a lag, certainly, and the filter will only make it worse if there wasn't one there before, particularly on the larger intakes if the 5.0 is MFI, not TBI. The TBI was a great idea to get rid of pumping losses from old Motorcraft 2150 2bbl technology, but please note it was VERY short lived. I wonder why?

But, if you want something to take care of the pulses at idle, the "filter" should do the trick, and probably won't have a super huge effect, obviously depending on how large you make it, and will still give ya something to respect. Gotta remember, this little reservoir is not quite as large as a tuna can in diameter, but slightly taller. My guess would be about the same volume as a small can of tuna. HINT: Take the tuna out before using the can for a filter.

I'll have to post a photo of what I refer to. Right now, though, I'd need hip waders. Its VERY wet here after nearly 7 inches of rain in the past three days. Lemme check the EVTM, though .... (Thanks again, jcassity) I'd be interested to see the differences in the vacuum setup for the 5.0 and 3.8 TBI systems.

(UPDATE) Just checked the EVTM, and no, it doesn't show the nifty little VRES near the MAP. Doesn't even show the MAP except the electrical portion at the EEC. I know I've seen that diagram somewhere ......

they say it cant be done....

Reply #17 – September 23, 2009, 04:41:48 PM

Quote from: Quietleaf;291834

I've definitely had a py idle ever since going to aftermarket cam+19# injectors+AFPR+65mm TB. I've learned to keep one foot on the brake one one on the gas when I'm stopped and the engine is still cold to stay above idle. I tried asking my mechanic to switch it to mass-air and he couldn't figure out how to make it work.

Quote from: Quietleaf;291841

Nope, I'm running the stock '87 SO computer. I don't know what cam is in it...maybe an 86 HO cam? The car runs fine above idle, it just idles py. When I get a chance I want to check my plugs again. They're only about a year old, but the idle was super-smooth for a few months after I put them in.

Quote from: Quietleaf;291851

I'd have to check (it's at the shop so I can't check now). I thought there are aftermarket 5.0 cams that keep the stock firing order. Isn't the 86 HO cam the same firing order?

I figured out your problem:D If you have a HO style cam (ie 1-3-7-2-6-5-4-8 firing order) then:

1. The SO computer is set up for a 1-5-4-2-6-3-7-8 firing order, which means that some of your injectors are not firing at the right time.
2. The SO computer is set up for 14lb injectors not 19lb injectors. No matter how much you mess with the fuel pressure it will not run right with the 19lb injectors.

I have an easy fix for you if the car has a HO style cam: remove the stock SO computer and stick in a HO SD computer from a Lincoln Mark VII. It's plug and play with no extra wiring for a MAF swap. That's the only way it will run right.

they say it cant be done....

Reply #18 – September 23, 2009, 04:52:12 PM

I have a SD HO Computer if you are interested. I believe its a DA1 program.

they say it cant be done....

Reply #19 – September 23, 2009, 08:47:45 PM

The car was brought back late today. I can take a look at the distributor cap tomorrow and see what it thinks the firing order is, but I have no way to tell what the cam is doing

What does DA1 mean?

they say it cant be done....

Reply #20 – September 24, 2009, 12:35:27 AM

Quote from: thunderjet302;292326

I have an easy fix for you if the car has a HO style cam: remove the stock SO computer and stick in a HO SD computer from a Lincoln Mark VII. It's plug and play with no extra wiring for a MAF swap. That's the only way it will run right.

87-89 mustang computer will also work. thats what is in mine.

they say it cant be done....

Reply #21 – September 24, 2009, 08:07:10 AM

*smacks head*

I'll just call my neighbor and ask him if they swapped in a crankshaft with a different firing order. They would have to have done that to change the firing order.

they say it cant be done....

Reply #22 – September 24, 2009, 09:14:05 AM

Quote from: Quietleaf;292410

I'll just call my neighbor and ask him if they swapped in a crankshaft with a different firing order. They would have to have done that to change the firing order.

The cranks are the same between the firing orders?

they say it cant be done....

Reply #23 – September 24, 2009, 09:14:12 AM

no they wouldnt

cranks are the same, cams are different.

they say it cant be done....

Reply #24 – September 24, 2009, 01:02:21 PM

Hmm. How would the cylinders be at TDC at the right time with the same crank? I don't understand.

they say it cant be done....

Reply #25 – September 24, 2009, 01:37:06 PM

Firing order is determined by the cam

Basically, the cams are different, instead of a certain piston being on the compression stroke, it's on the exhaust stroke, or what have you. The cam (and thusly the firing) is different from the SO to the HO to make this work...not ALL the cylinders are on different orders, just a few. Hope this helps to clear the confusion.

I too once thought it impossible...but it works lol...

they say it cant be done....

Reply #26 – September 24, 2009, 04:01:14 PM

Okay, I think I get it...it's moving the intake and exhaust strokes.

Anyhow, there's something fishy here. My firing order is the SO order (1-5-4-2-6-3-7-8), and my injectors definitely don't look like 19# ones (or if they are, they're the only tan-colored ones I've ever seen). I'm wondering if I need to just order everything I need and have my neighbor put them in. Are 19# injectors *always* orange, or are some tan? Is there a way I can tell what they are?

they say it cant be done....

Reply #27 – September 24, 2009, 04:13:19 PM

Tan/Orange=19#, Grey=15#.
I have 19#s that are more tanish than orange.

they say it cant be done....

Reply #28 – September 24, 2009, 04:22:28 PM

This is the best picture I was able to take with my camera a few minutes ago...

they say it cant be done....

Reply #29 – September 24, 2009, 04:28:28 PM

Closeup of the numbers, if they mean anything...

650
150710