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Where is my vacuum going?!

Sounds like something is not right. Best aproach will be so see the data and see where the fuel trim sits and other data.
 
crash said:
Sounds like something is not right. Best aproach will be so see the data and see where the fuel trim sits and other data.
Click to expand...

True seeing the data is the best bet but I don't think this is fuel trim related. No doubt the trim is off being this is not a custom adjusted chip.
 
I will assume you can program the prom with either being a manual or auto? I would have to guess the prom in it is from a auto and there is no p/n switch input which could be causing an issues since the fuel mapping/iac are different from an auto/manual (particularly at idle is where it would be noticed)
 
If it does any sort of timing control, it's not via the distributor because they had us disable both vac and mechanical... :scratchhead:

No user programming of the PROM, we ordered it for an automatic...
 
tobyw said:
If it does any sort of timing control, it's not via the distributor because they had us disable both vac and mechanical... :scratchhead:

No user programming of the PROM, we ordered it for an automatic...
Click to expand...

Well being it has an auto and probably no p/n switch input---that could be an issue....
 
No distributor timing being an issue you mean, or the lack of a p/n switch input??

FWIW, I put a very similar system on the SBC in my YJ, which was also an automatic with no p/n input switch, and had zero issues???
 
tobyw said:
If it does any sort of timing control, it's not via the distributor because they had us disable both vac and mechanical... :scratchhead:
Click to expand...

This may not be THE problem but it sure is A problem. In fact that's full on retarded. You need to have advance capability of your timing. Do you still have the directions and could you post them up maybe with company names blacked out? Odds are they gave you poor directions on initial setup and compound that with the lack of timing conrol what's left is a pile of non running ****.:rolleyes:
The prom can be adjusted for auto- manual transmissions but it's not as simple as it sounds......Can you post the numbers and letters printed on the computer? There should be a 7 to 8 digit number and 4 digit letters....
 
Binder said:
This may not be THE problem but it sure is A problem. In fact that's full on retarded. You need to have advance capability of your timing. Do you still have the directions and could you post them up maybe with company names blacked out? Odds are they gave you poor directions on initial setup and compound that with the lack of timing conrol what's left is a pile of non running ****.:rolleyes:
The prom can be adjusted for auto- manual transmissions but it's not as simple as it sounds......Can you post the numbers and letters printed on the computer? There should be a 7 to 8 digit number and 4 digit letters....
Click to expand...

I always thought it was a little odd myself, but never gave it much thought because I have NO idea how the whole EFI brain works... Always figured it was smarter than me :redneck:

I won't have access to the rig or the instructions until this weekend, but I'd sure be happy to scan them in and post the pages up as images... I will also try to get a computer number for you...
 
The P/N switch thing shouldn't be a problem as long as the idle is high enough when it's in gear. They should have compensated for this in the chip before they sent it to you. You won't know the answer to that until you get the surging idle issue worked out......
Have you tried to adjust the idle yourself?
 
No, I haven't... When it idles down, it seems to purr quite nicely. And when it doesn't jump in RPM when you drop it into gear, it also seems spot on? But when it decides to ramp up, it's a PITA!!

Reading back through this, the one thing I forgot to mention is that it doesn't do it nearly as often or as badly in High Range, but it's instant and gross in Low Range.
 
Wow Toby it sure sounds like your dad ended up with a sweet setup...

If it was mine I'd either attempt to add in a tbi conversion distributor from D.U.I. or junk that wiring harness completely and put a fomoco junkyard setup on it and be done...
 
tobyw said:
No, I haven't... When it idles down, it seems to purr quite nicely. And when it doesn't jump in RPM when you drop it into gear, it also seems spot on? But when it decides to ramp up, it's a PITA!!

Reading back through this, the one thing I forgot to mention is that it doesn't do it nearly as often or as badly in High Range, but it's instant and gross in Low Range.
Click to expand...


It's good that you didn't try to adjust the idle as it's not user adjustable. This is a common mistake people make. This system has what is called a stall saver which means it will kick up the idle to avoid letting the engine die. It sounds to me like the stall saver is kicking in a bit too much. Could be many different possible reasons for it to do this. If it were mine the first thing I would do is put the distributor back like it was. After that verify the initial setup was done correctly...........
Where's Bill when you need him? I'll try to get him to give his two cents.
 
WHITE TRASH said:
Wow Toby it sure sounds like your dad ended up with a sweet setup...

If it was mine I'd either attempt to add in a tbi conversion distributor from D.U.I....
Click to expand...

This would be a great option but would require adding in wires to the harness and starting over with a different chip. May end up doing that in the end anyways.
If the engine is modded in any way don't try to use a stock Ford setup. It MIGHT work but probably not well and is nearly impossible to custom tune the chip worth a damn.
 
Binder said:
It's good that you didn't try to adjust the idle as it's not user adjustable. This is a common mistake people make. This system has what is called a stall saver which means it will kick up the idle to avoid letting the engine die. It sounds to me like the stall saver is kicking in a bit too much. Could be many different possible reasons for it to do this. If it were mine the first thing I would do is put the distributor back like it was. After that verify the initial setup was done correctly...........
Where's Bill when you need him? I'll try to get him to give his two cents.
Click to expand...

stall saver---intersesting. I have never heard that term used before....
 
No mods, just a basic rebuild and balanced.

I'll reread the instructions this weekend and try to figure out where they were going with the distributor, and re-enable at least the mechanical advance. I will also tear the front end off and see wtf is up with the cam to hopefully shed some light on the low vacuum issue...
 
Binder said:
It could be called different things but stall saver is what all of the chip editing programs call it.
Click to expand...

Ok--thats where it comes from. I assume its a programable number in refernce to the IAC counts--or something to that nature?
 
crash said:
Ok--thats where it comes from. I assume its a programable number in refernce to the IAC counts--or something to that nature?
Click to expand...

It's a combination of several programable two and three dimensional tables, there are many factors. Yes it basically steps up the IAC counts and in turn the fuel and timing with it. I'm curious if the lack of timing control could be screwing with the stall saver being timing input is missing.
 

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