Binder
Well-Known Member
Does you distributor have a magnetic pickup? You only lock down the vacuum/mechanical advance if you do this magnetic pickup mod to the distributor.
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Help Support Hardline Crawlers :
Where is my vacuum going?!
- Thread starter tobyw
- Start date
Does you distributor have a magnetic pickup? You only lock down the vacuum/mechanical advance if you do this magnetic pickup mod to the distributor.
WHITE TRASH1
fruit stripe
Is the tbi system very touchy to vacuum? It just ocurred to me (and I called my trans guru brother to double check) that the issue isn't there in reverse... The modulator doesn't leak vacuum but it does use it in forward gears only. Unplug the modulator and give it a go. If it clears up find where the leak is in that line, if not unplug the booster.
I agree the system has issues but there isn't a physical link from the 'puter to the trans or brakes, only vacuum. Unless that anti stall system is reading off of the MAPP sensor and forcing the IAC valve fully open when the vacuum reading drops a bit...
I agree the system has issues but there isn't a physical link from the 'puter to the trans or brakes, only vacuum. Unless that anti stall system is reading off of the MAPP sensor and forcing the IAC valve fully open when the vacuum reading drops a bit...
Binder
Well-Known Member
Does the distributor plug into the TBI harness? So it sounds like you do have timing control then.
crash2
-Oh no I picked a side-
It would have to have some kind of magnetic pickup---otherwise you would have no reference to the ecm for injector pulse.
Binder
Well-Known Member
You could be right about the modulator line as we just don't know for sure at this point what's going on. The system works as a whole so yes MAP input will play a roll in the stall saver. More likely the "lug" of the engine when shifted into gear drops the RPM just enough to trigger the stall saver assuming it's a stall saver issue at all.
Really all of this stuff is just guess work as we only know so much about the rig and what it's doing. It's hard to troubleshoot someones rig over the web but given enough information we may be able to figure it out.
Binder
Well-Known Member
Yes it does need a RPM input but not necessarily a timing control. Many of these aftermarket systems are fuel only but they're intended to be used with the original timing system intact. You could run a fuel only with a points dist or MSD or ....
Binder
Well-Known Member
Binder
Well-Known Member
Something I just noticed is that in the background of that last pick there are clearly two ECMs. I assume you only have one?
crash2
-Oh no I picked a side-
True--but if its a stock prom--you would have 42 stored and no timing advance...
Binder
Well-Known Member
You have computer timing control. Does your system use a knock sensor? Just curious as it has nothing to do with the problem you having.
Binder
Well-Known Member
42 would be turned off in the chip and correct, no timing advance that's why you leave in the stock stuff.
Bill USN-1
Active Member
Just read thru the thread forwarded to me from Rick.
The system is identical to what we have posted on the binderplanet.
With the use of the 8 pin and the DS distr it has full timing control.
If everything is just as described and the idle still jumps with the IAC driven closed and unplugged, then the only thing that can be changing is the timing based on a change in load/vacuum.
To start with i would recommend going to the FAQ's on the binderplanet. First hit the wiring FAQ and grab sheet 1.
It will list the Key on and engine running voltage checks. Do both.
Next hit the parts required FAQ and grab the table for the MAP sensor and make sure it is within specs.
I have not seen a location listed for the vehicle so i don't know the alt. But check the local weather channel.
I would also plug the vacuum modulator and remove the map and shake it with the nipple down to see if any liquid is in it. Tranny fluid from a bad modulator or fuel from the sensor mounted too low.
The map needs to be mounted above the center rear TBI vacuum port where it's connected.
The nipple should be pointed down if possible.
When all is checked, then I would go to the initial setup procedures and follow them.
If you have a laptop and the data cable, then you should also follow the how to tune FAQ for what data to log and save.
But you need some real trouble shooting to seperate fact from fiction.
The position of the transfer case lever or rev or drive have no affect on the system.
The system is identical to what we have posted on the binderplanet.
With the use of the 8 pin and the DS distr it has full timing control.
If everything is just as described and the idle still jumps with the IAC driven closed and unplugged, then the only thing that can be changing is the timing based on a change in load/vacuum.
To start with i would recommend going to the FAQ's on the binderplanet. First hit the wiring FAQ and grab sheet 1.
It will list the Key on and engine running voltage checks. Do both.
Next hit the parts required FAQ and grab the table for the MAP sensor and make sure it is within specs.
I have not seen a location listed for the vehicle so i don't know the alt. But check the local weather channel.
I would also plug the vacuum modulator and remove the map and shake it with the nipple down to see if any liquid is in it. Tranny fluid from a bad modulator or fuel from the sensor mounted too low.
The map needs to be mounted above the center rear TBI vacuum port where it's connected.
The nipple should be pointed down if possible.
When all is checked, then I would go to the initial setup procedures and follow them.
If you have a laptop and the data cable, then you should also follow the how to tune FAQ for what data to log and save.
But you need some real trouble shooting to seperate fact from fiction.
The position of the transfer case lever or rev or drive have no affect on the system.
Last edited:
Binder
Well-Known Member
Thanks Bill. I thought you may have some sensible input to add.:awesomework:
zukkev
Cornfuzzled yet again...
Yup, learned that thru the school of hard knocks on a buddy's 89 F150 many yrs ago, 1995ish IIRC ...
I'll check that FAQ out and go from there - many thanks! For reference, the MAP does not have any liquid in it and it is indeed mounted above the TBI unit. I am thinking the reason it happens worse in Low-Range is because it loads the motor quicker... And yes, with the IAC closed and unplugged the condition remains, so we appear to be on the right track with a vacuum issue... I'll block off the modulator line first and report back. With any luck, that'll be the culprit?! :corn:
ljtoy
Member
Try replacing the vacuum check valve at the booster line to booster connection.
